Microbio Module 2 Flashcards

What 2 repeating disaccharide units constitute peptidoglycan?

Peptidoglycan synthesis begins in the bacterial cytoplasm. Which molecule is first made as a sugar-building block?

____-____

What is the purpose of attaching NAM to UDP?

To activate _____ for later _____ _____ synthesis

Which lipid carrier helps move peptidoglycan building blocks across the bacterial cytoplasmic membrane?

A. Cholesterol
B. Cardiolipin
C. Bactoprenol
D. Ergosterol

UDP-NAM attaches to bactoprenol through what type of linkage?

A. Peptide bond
B. Glycosidic bond
C. Disulfide bond
D. Pyrophosphate linkage

When UDP-NAM attaches to bactoprenol, which molecule is released?

_____

After NAM attaches to bactoprenol, what happens next?

The unit is moved across the ____

Which enzyme moves the bactoprenol-linked peptidoglycan precursor to the outside surface of the membrane?

_____

Where is the NAG-NAM disaccharide added to the growing peptidoglycan chain?

A. Inside the nucleus
B. In the bacterial cytoplasm
C. Outside the plasma membrane
D. Inside the mitochondria

Which sequence best summarizes peptidoglycan synthesis?

A. Cross-link peptides → make UDP-NAM → flip bactoprenol → attach NAG-NAM
B. Make UDP-NAM → attach to bactoprenol → flip outside → add to peptidoglycan
C. Attach to ribosome → make protein → export protein → form capsule
D. Make Lipid A → attach O antigen → flip LPS → form outer membrane

Transpeptidation in peptidoglycan synthesis mainly refers to what process?

A. Sugar activation
B. Peptide cross-linking
C. Bactoprenol flipping
D. NAM synthesis

The transpeptidation reaction forms a bond between peptide side chains attached to which sugar?

_____

The free amine used in transpeptidation is usually located on which position of the pentapeptide?

_____

In many Gram-positive bacteria, the 3rd-position amino acid involved in cross-linking is commonly ______.

The 3rd-position amino acid cross-links to which residue on a neighboring chain?

A. 1st-position alanine
B. 2nd-position glutamate
C. 4th-position D-alanine
D. 5th-position D-alanine

What happens to the terminal D-alanine during transpeptidation?

A. It becomes NAG
B. It is released
C. It binds UDP
D. It becomes bactoprenol

Which enzyme performs the transpeptidation reaction?

Penicillin-binding proteins are important because they normally function as _____.

Beta-lactam antibiotics inhibit bacterial growth mainly by blocking:

A. NAM production
B. NAG transport
C. Peptidoglycan cross-linking
D. Folate synthesis

Lipoteichoic and teichoic acids are assembled from activated building blocks on the _____ and then translocated to the outer surface

Which organism is the most likely cause of hemorrhagic colitis?

A. Enterotoxigenic Escherichia coli
B. Escherichia coli O157:H7
C. Shigella sonnei
D. Campylobacter jejuni

Which constituent of the Gram-positive bacterial cell wall is responsible for sequestration of Ca²⁺ ions?

____ ____

Unlike most Gram-negative bacteria, Neisseria species contain which endotoxin in their outer membrane?

_______ (____ )

A light microscope has a resolution of ____ μm

The diameter of a red blood cell is ____ μm

Where does ATP production occur in prokaryotes?

____

What bacteria cannot be classified by Gram staining?

____

____

Where are bacterial chromosomes present in the cell?

____

The prokaryotic ribosome consists of _____ and _____ subunits, forming a _____ ribosome

The eukaryotic ribosome consists of _____ and _____ subunits, forming a _____ ribosome

What is the difference between cytoplasmic membranes of eukaryotes and prokaryotes?

Eukaryotes- _____ _____
Prokaryotes- _____ _____

Mycoplasma contains no _____

Peptidoglycan can be degraded by _____

lysozyme is found in human _____ and _____.

lysozyme cleaves _____ backbone of peptidoglycan

Lysozyme is able to cleave the ____-1,4 ____ linkage in peptidoglycan

The presence of peptidoglycan in the cell well protects bacteria from damage against ____ ____.

Disruption of the _____ _____ can provide entry of lysozyme to produce _____, which, like protoplasts, are osmotically sensitive.

Removal of a cell wall produces a _____ that _____ unless it is osmotically stabilized

What is the periplasmic space in gram negative baceteria?

space between the:
1. _____ membrane
2. _____ membrane

What is the function of the periplasmic space?

1. Contains components of transport systems for ______ and ______
2. Contains ______ enzymes

What genus causes rabbit/deer fever, AKA tularemia?

_____

Lipoteichoic acid is only present in gram-______ bacteria. Lipoteichoic acid is anchored in the ______ ______ and extend towards the exterior

In bacteria, immediately external to the cytoplasmic membrane is _______.

The Shwartzman reaction is the event that occurs in disseminated _____ coagulation when there is a release of a large amount of _____.

What protein restricts the entry of large and hydrophobic molecules across the outer membrane?

_____

The outer membrane is connected to the _____ _____ at adhesion sites and is tied to the _____ by _____.

Disruption of the outer membrane can provide entry of _____ to produce _____

The capsule and slime layer of the cell are both usually made up of _____

Bacillus anthracis produces a _____ capsule

_____ _____ will produce a polysaccharide biofilm when sufficient numbers are present. When sufficient numbers are present, this is referred to as a _____.

A _____ is a sticky protective layer that helps bacteria attach to surfaces and resist antibiotics, immune cells, and disinfectants.

_____ _____ forms a _____ and _____ biofilm which promotes adhesion to tooth enamel and forms tooth-like plaque

What determines if a bacteria swims or tumbles when trying to find a chemoattractant?

____ of ____ spinning

What is the role of fimbriae?

promote adherence of _____ to _____ _____

What are the 3 constituents of LPS?

1. ____ ____ (responsible for ____ activity)
2. ____ ____
3. ____ ____

During cell division, the production of 2 daughter bacteria requires growth and extension of the cell wall components followed by the production of a ____ to divide the 2 cells.

For streptococci, the growth zone is located ____^o from each other and for staphylococci, the growth zone is located ____^o from each other

The outer coat of a spore contains the protein _____

How do spores form?

depletion of specific ______ (______) from the ______ medium

What makes the mycobacterial cell wall unusually waxy and acid-fast?

A. Teichoic acid
B. Mycolic acid
C. Lipooligosaccharide
D. Capsule polysaccharide

In mycobacteria, peptidoglycan is covalently attached to which polymer?

A. Arabinogalactan
B. Lipid A
C. KDO
D. D-Ala-D-Ala

Bacitracin inhibits peptidoglycan synthesis by blocking recycling of:

A. D-Ala-D-Ala
B. Transpeptidase
C. Phosphobactoprenol
D. Arabinogalactan

Penicillin acts as a structural analog of which peptidoglycan component?

A. NAG-NAM
B. D-Ala-D-Ala
C. KDO
D. Mycolic acid

Why does transpeptidase bind penicillin?

A. Penicillin resembles D-Ala-D-Ala
B. Penicillin resembles teichoic acid
C. Penicillin resembles Lipid A
D. Penicillin resembles arabinogalactan

What happens after transpeptidase binds penicillin?

A. Peptidoglycan cross-linking increases
B. Transpeptidase is inactivated
C. Bactoprenol recycling increases
D. Mycolic acid synthesis increases

The core region of LPS contains which phosphorylated sugar?

A. D-alanine
B. N-acetylglucosamine
C. 2-keto-3-deoxy-octanoate
D. Arabinose

Why are Neisseria species more susceptible to host-mediated complement lysis?

They lack the ___-antigen portion of ___

In Neisseria, lack of O antigen allows LOS aggregates to be shed, which reduces:

A. Ribosomal protection
B. Complement protection
C. DNA replication
D. Spore formation

What can stimulate germination of a bacterial spore into the vegetative state?

______ of the outer ______-like protein coat

______ stress or ______ changes can trigger spore germination.

About how long does spore germination take?

A. 5 minutes
B. 30 minutes
C. 90 minutes
D. 24 hours

A bacterium has a structure that can be targeted by both the immune system and antibiotics. Which structure is being described?

____ ____

Gram-positive bacteria have a much thicker cell wall due to increased amounts of what? A. Lipopolysaccharide B. Peptidoglycan C. Sterols D. Mycolic acid

Which structure is present in gram-positive bacterial cell walls?

A. Lipopolysaccharide B. Lipoteichoic acid C. Outer membrane D. Sterols

Which bacterium does not Gram stain because it lacks a cell wall?

A. Mycoplasma

B. Mycobacteria

C. Bacillus

D. Neisseria

Mycoplasma lacks a cell wall but maintains membrane stability using what?

A. Mycolic acids

B. Lipopolysaccharide

C. Sterols

D. Teichoic acids

Which bacteria have cell walls containing mycolic acid?

A. Mycobacteria

B. Mycoplasma

C. Neisseria

D. Streptococcus

Mycobacteria are best visualized using which special stain?

A. Gram stain

B. Capsule stain

C. Ziehl-Neelsen acid-fast stain

D. India ink stain

Why do mycobacteria require an acid-fast stain instead of a standard Gram stain?

A. They lack ribosomes

B. Their cell walls contain mycolic acid

C. They contain endotoxin

D. They have no cell membrane

Mycobacteria include organisms that cause which diseases?

A. Syphilis and Lyme disease B. Cholera and plague C. Botulism and tetanus D. Tuberculosis and leprosy

Electron transport and oxidative phosphorylation occur on which bacterial structure?

Gram-negative bacteria can resist some antibiotics because enzymes are located in which space?

______

β-lactamase in the periplasm of gram-negative bacteria helps resist which type of treatment?

A. Antiviral therapy

B. Antifungal therapy

C. β-lactam antibiotic therapy

D. Antiprotozoal therapy

Which molecule on the surface of gram-negative bacteria drives a strong immune response?

A. Lipopolysaccharide

B. Sterol

C. Teichoic acid

D. Peptidoglycan

Lipopolysaccharide is found on which structure?

A. Gram-positive cell wall

B. Mycoplasma membrane

C. Outer membrane of gram-negative bacteria

D. Cytoplasmic membrane of gram-negative bacteria

Which part of lipopolysaccharide is a major antibody target?

A. O antigen

B. Lipid A

C. Core polysaccharide

D. Peptidoglycan

IgG antibodies bind bacterial capsules and promote phagocytosis through which receptor interaction?

A. T-cell receptors

B. Fc receptors

C. B-cell receptors

D. Sterol receptors

IgG binding to a bacterial capsule can also promote which immune pathway?

A. Histamine release

B. Complement binding

C. Viral budding

D. Fungal dimorphism

Lack of B cells, antibodies, or complement increases susceptibility to which type of bacterial infection?

A. Encapsulated bacterial infections

B. Intracellular viral infections

C. Dimorphic fungal infections

D. Spirochetal infections

Asplenia increases the risk of sepsis from which type of bacteria?

A. Acid-fast bacteria B. Anaerobic bacteria C. Intracellular bacteria D. Encapsulated bacteria

Why does asplenia increase susceptibility to encapsulated bacteria?

A. Loss of thymic selection

B. Loss of neutrophil oxidative burst

C. Loss of splenic phagocytes

D. Loss of T-cell receptors

Which set contains classic encapsulated organisms remembered by SHiNS?

A. Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Salmonella

B. Staphylococcus aureus, Helicobacter pylori, Neisseria gonorrhoeae, Shigella

C. Streptococcus pyogenes, Histoplasma, Nocardia, Salmonella

D. Shigella, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus epidermidis

Bacterial capsular polysaccharides are the basis for many what?

A. Gram stains B. Acid-fast stains C. Antibiotic resistance genes D. Vaccines

Which organisms are commonly targeted by polysaccharide capsule-based vaccines?

A. Staphylococcus aureus, Helicobacter pylori, Neisseria gonorrhoeae

B. Shigella, Salmonella, Bacillus anthracis

C. Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis

D. Mycoplasma, Mycobacteria, Trichophyton

A bacterium has an irregular, fuzzy outer layer. Which structure is being described?

______

A bacterium has a distinct, firmly attached gelatinous layer. Which structure is being described?

______

Pili or fimbriae in E. coli help cause which infections?

A. Meningitis and encephalitis

B. Pneumonia and endocarditis

C. Syphilis and Lyme disease

D. UTIs and pyelonephritis

Small DNA elements within bacteria that replicate independently are called _____.

Which bacterial DNA element can carry genes for antibiotic resistance or toxins?

A. Plasmid

B. Flagellum

C. Capsule

D. Lipopolysaccharide

Why are plasmids clinically important?

They can transfer _____ _____ between bacteria

Some bacteria can enter a dormant survival state called what?

What is true of bacteria in spore form?

A. They are metabolically hyperactive

B. They immediately divide

C. They replicate viruses

D. They can survive long periods in extreme conditions

Which conditions can bacterial _____ survive?

Lack of nutrients, dehydration, heat, and chemicals

The middle layer, or cortex, of a bacterial spore is made of what?

A. Mycolic acid

B. Lipopolysaccharide

C. Peptidoglycan

D. Sterols

The core of a bacterial spore contains _____, _____, and _____ enzymes

Which genera are known as spore-forming bacteria?

____ and ____

Spore-forming Bacillus and Clostridium are usually classified as what?

gram-____ bacteria

What substance is present in the core of a bacterial spore?

_____ bound to dipicolinic acid

Which bacteria have branched filamentous appearances?

A. Neisseria and Streptococcus pneumoniae

B. Bacillus and Clostridium

C. Nocardia and Actinomyces

D. Staphylococcus and E. coli

Which bacteria are classically diplococci?

A. Streptococcus pneumoniae and Neisseria

B. Nocardia and Actinomyces

C. Bacillus and Clostridium

D. E. coli and Salmonella

Which bacterium classically forms chains?

A. Staphylococcus aureus

B. Neisseria meningitidis

C. Bacillus anthracis

D. Streptococcus pyogenes

A spherical bacterium is called what?

A. Bacillus B. Coccus C. Spirillum D. Spore

A rod-shaped bacterium is called what?

A. Coccus B. Spirillum C. Bacillus D. Diplococcus

A snakelike bacterium is called what?

A. Spirillum B. Coccus C. Bacillus D. Spore

In the gram-negative outer membrane, what makes up the outer leaflet?

_____

In the gram-negative outer membrane, what makes up the inner leaflet?

_____

Which ions help hold the gram-negative outer membrane together by linking phosphates on LPS?

______ and ______

Which interaction helps stabilize the gram-negative outer membrane?

______ interactions between ______ and ______

During Gram staining, which stain is applied first?

_____ _____

During Gram staining, crystal violet is precipitated with which substance?

_____

During Gram staining, unbound and excess stain is removed using what?

______-based decolorizer and ______

Serotyping bacteria involves distinguishing bacteria using antibodies against what?

A. Ribosomal subunits

B. Characteristic antigens

C. Mitochondrial proteins

D. Host cytokines

What is the purpose of safranin in Gram staining?

A. To stain decolorized cells red

B. To precipitate crystal violet

C. To dissolve mycolic acid

D. To form spores

Which process uses antibodies to detect characteristic bacterial antigens?

A. Gram staining

B. Acid-fast staining

C. Serotyping

D. Spore staining

Which organisms do not contain a peptidoglycan cell wall?

A. Bacillus and Clostridium

B. Streptococcus and Neisseria

C. Staphylococcus and E. coli

D. Archaea and mycoplasms

Teichoic acids in gram-positive bacteria are what type of molecules?

A. Neutral lipid droplets

B. Water-soluble anionic polymers of polyol phosphates

C. Sterol-rich membrane anchors

D. Protein toxins

Teichoic acids are covalently linked to which bacterial structure?

_____

Why are teichoic acids important in gram-positive bacteria?

They are essential to _____ viability

Which gram-positive cell wall component is linked to innate immune activation?

A. O antigen

B. Lipoteichoic acid

C. Sterol

D. Plasmid

Which bacterial structure is most associated with antibiotic resistance gene transfer?

_____

Which structure allows bacteria to survive extreme conditions with little to no metabolic activity?

_____

Do gram-negative bacterial cell walls contain teichoic or lipoteichoic acids? A. Yes, both are present B. Only teichoic acid is present C. Only lipoteichoic acid is present D. No, neither is present

What is one major function of the gram-negative outer membrane?

A. Production of ribosomes

B. Formation of spores

C. Storage of plasmids

D. Permeable barrier

The outer leaflet of the gram-negative outer membrane contains which molecule

A. Teichoic acid

B. Lipopolysaccharide

C. Sterols

D. Mycolic acid

Lipopolysaccharide in gram-negative bacteria stimulates which host response?

A. Innate immune response

B. Somatic hypermutation

C. T-cell receptor rearrangement

D. Antibody class switching

A gram-negative bacterium triggers a strong innate immune response through LPS. Where is this LPS located?

A. Inner leaflet of cytoplasmic membrane

B. Peptidoglycan cortex

C. Outer leaflet of outer membrane

D. Bacterial chromosome

Porins in the gram-negative outer membrane allow diffusion of which molecules?

A. Hydrophobic molecules

B. Large proteins only

C. Steroid hormones only

D. Hydrophilic molecules

A small _____ molecule crosses the gram-_____ outer membrane through porin.

The bacterial flagellum is best described as what?

A. An external structure used for movement

B. A DNA element that carries resistance genes

C. A polysaccharide layer used for immune evasion

D. A membrane pore for hydrophilic molecules

A bacterium living in a biofilm becomes harder for antibiotics and immune cells to eliminate. What is the main advantage of the biofilm?

A. Increased oxygen use

B. Increased sporulation

C. Protection

D. Loss of virulence

Which two polysaccharide components make up bacterial peptidoglycan?

A. Glucose and fructose

B. Ribose and deoxyribose

C. N-acetylglucosamine and N-acetylmuramic acid

D. Cellulose and glycogen

Transpeptidases and carboxypeptidases involved in peptidoglycan synthesis are targets of which antibiotics?

A. Macrolides and a-lactam antibiotics

B. Tetracyclines and a-lactam antibiotics

C. Fluoroquinolones and β-lactam antibiotics

D. Penicillins and β-lactam antibiotics

Penicillin and β-lactam antibiotics target enzymes involved in which process?

Peptidoglycan ______

A bacterium forms spores. It is most likely classified as which Gram stain type?

A bacterial spore contains how many peptidoglycan layers?

Which structure is part of a bacterial spore?

A. Outer membrane with LPS

B. Sterol-rich membrane only

C. Inner membrane

D. Teichoic acid layer

High concentrations of dipicolinic acid in bacterial spores help stabilize contents by binding what?

A. Sodium B. Magnesium C. Potassium D. Calcium

Which spore component helps stabilize the spore contents by binding calcium?

A. Peptidoglycan

B. Dipicolinic acid

C. Lipopolysaccharide

D. Porin

Which sequence best describes bacterial cell division?

A. Cell wall growth and extension → septum formation → two daughter bacteria

B. Septum formation → loss of cell wall → viral budding

C. Spore coat formation → LPS release → two daughter bacteria

D. Flagellar movement → capsule loss → chromosome deletion

____ is so important that many bacteria secrete special proteins called ____ to concentrate ____ from dilute solutions

What organism causes gas gangrene?

____ ____

What are obligate anaerobes?

organisms that ____ grow in the presence of ____ (____ ____)

What are obligate aerobes?

organisms that require ____ for metabolism and growth

What are facultative anaerobes?

1. May use ____ as a terminal ____ ____ to generate ____

2. Can also use ____ and other ____ -independent pathways

Aerobic bacteria produce the following 2 enzymes:

1. _____ _____

2. _____

What are autotrophs?

_____ that can rely solely on _____ chemicals for their energy and source of carbon

What are heterotrophs?

_____ and _____ cells that require _____ carbon sources

The _____ species can improve the function of the normal GI flora

______: small molecules are assembled into large ones using energy

______: substrate breakdown and conversion into usable energy

______ of the colon can select for and promote the growth of beneficial ______ -producing endogenous bacteria

Electrochemical energy is stored by the _____ of _____ to _____

What enzyme drives the spinning of flagella and drives the conversion of ADP into ATP?

1. What is the most efficient way in which bacteria can produce energy from glucose?

2. What is the least efficient way in which bacteria can produce energy from glucose?

Fermentation results in the conversion of _____ into _____ and _____

Alcoholic fermentation uses the one-step conversion of _____ acid into _____ acid

What is the theoretical yield from each molecule of pyruvate in the TCA cycle?

____ NADH

____ FADH2

____ CO2

____ GTP

Acetyl CoA enters the TCA cycle by combining with _____ to form the molecule _____

What is the most efficient mechanism for the generation of ATP?

Fermentation produces only _____ ATP molecules per glucose.

Aerobic metabolism with ETC and a complete TCA cycle can generate as much as _____ ATP molecules from the same starting material

Deamination of glutamic acid yields _______ and deamination of aspartic acid yields _______

The ETC resides in the ____ ____ of bacteria.

It uses electrons obtained from ____ and ____ to produce a transmembrane proton electrochemical gradient that drives the ____ ____ and powers transport and flagella

What is the function of the pentose phosphate pathway (HMP shunt)?

1. Provides _____ _____ precursors

2. Provides a source of _____

The normal flora of our body process complex carbohydrates and releases _____-_____ _____ _____ as products of _____

The bacterial DNA-dependent RNA Polymerase is inhibited by _____ which is an antibiotic often used in the treatment of _____

How does bacterial protein synthesis begin?

binding of the:

1. ____ ribosomal subunit and the

2. Special initiator ____ for formyl methionine (____) at the ____ start codon to form the initiation complex

Increased cAMP levels indicate ____ ____ levels

The _____ sequence of the tRNA binds to the _____ sequence on the mRNA

The trigger for biofilm production by Pseudomonas spp. is triggered by a critical concentration of N-acyl homoserine lactone (_____) produced when sufficient numbers of bacteria are present.

Activation of biofilm, toxin production, and more virulent behavior by Staphylococcus aureus accompanies the increase in concentration of a _____ _____.

What class of drugs are 30s ribosomal subunit inhibitors?

1. _____ (_____ and _____)

2. _____

What class of drugs are 50s ribosomal subunit inhibitors?

1. _____

2. _____ (_____)

3. _____ (_____)

4. _____

_____ peptides are chemotactic and attract neutrophils to the site of infection

What is the role of a repressor protein?

binds to a specific ____ sequence within the ____, blocking ____ ____ from initiating ____ at the ____ sequence

In the lac operon, what occurs when there is an absence of lactose?

repressor protein binds to the _____ sequence

In the lac operon, what occurs when there is an absence of glucose?

1. _____ binds to catabolite activator protein (CAP)

2. CAP-cAMP complex enhances binding of _____ _____ to the promoter = _____ _____

When are Salmonella pathogenicity islands turned on?

1. High _____

2. Low _____

These conditions are present in the GI tract/endosomal vesicle within a macrophage

What can activate expression of hemolysin in E. coli or diphtheria toxin from Corynebacterium diphtheriae?

low ____ levels

for lac operon

No _____→ repressor bound → operon _____
_____ present → repressor removed → operon can turn _____

In DNA synthesis, the _____ strand is synthesized _____ whereas the lagging strand is synthesized as many pieces of DNA using _____ _____ , creating _____ fragments

The lagging strand DNA must be extended in the ____' to ____' direction as its ____ becomes available. Then, DNA pieces are connected via the enzyme ____ ____

What is the role of DNA topoisomerase?

creates ____ in the ____ to add or remove ____ in the ____

What class of drugs targets topoisomerases in prokaryotes

_____ antibiotics

Depletion of metabolites or a buildup of toxic by-products triggers production of chemical ______

When bacteria are added to a new medium, they require time to adapt to the new environment before they begin _____. This phase is known as the _____ _____ of growth.

During the ____ ____ phase, the bacteria will grow and divide with a doubling time

1. What occurs in a transition base change?

___ to ___ or ___ to ___

2. What occurs in a transversion base change?

___ to ___ or ___ to ___

What are the 3 proteins in which the lac operon can be transcribed and translated into?

_____- β galactosidase

_____- permease

_____- acetylase

An E. coli cell is exposed to a high intracellular concentration of tryptophan. During transcription of the trp operon leader region, the ribosome moves quickly through the leader peptide. Which RNA hairpin forms?

A. Regions 1 and 2
B. Regions 2 and 3
C. Regions 3 and 4
D. Regions 1 and 4

In the trp operon, formation of the 3–4 hairpin loop causes which outcome?

A. Increased translation of tryptophan biosynthetic enzymes
B. Premature termination of transcription
C. Binding of allolactose to the repressor
D. Activation of CAP-cAMP

An E. coli cell has low intracellular tryptophan levels. The ribosome stalls at the tryptophan codons in the leader peptide. Which hairpin forms, allowing transcription to continue?

A. Regions 2 and 3
B. Regions 3 and 4
C. Regions 1 and 4
D. Regions 1 and 3

What occurs in a silent mutation?

a change at the ____ level that codes for the ____ amino acid

What occurs in a missense mutation?

1. Results in a _____ amino acid

2. Called a _____ mutation if _____ amino acid has similar chemical structure

What occurs in a nonsense mutation?

results in an _____ _____ _____

A small deletion or insertion that is not in multiples of three produces a _____ mutation.

This results in a change in the reading frame, usually leading to a useless _____ and premature truncation of the _____.

What occurs in a Null mutation?

1. Arise when there is an extensive insertion, deletion, or gross rearrangement of _____ structure

2. Completely destroys _____ function

Heat can induce mutations by causing ____ of ____

DNA-reactive chemicals such as ____ ____ act directly on the DNA to change the chemical structure of the base

A researcher exposes bacterial DNA to 5-bromouracil (5-BrU). Which property of 5-BrU is primarily responsible for its mutagenic effect?

It can base-pair with ____ instead of ____

5-Bromouracil is classified as which type of mutagen?

A. Alkylating agent
B. Intercalating agent
C. Nucleotide-base analog
D. Depurinating agent

Ethidium bromide causes mutations primarily by which mechanism?

_____ between stacked DNA bases

What occurs in base excision repair?

1. Base specific _____ removed altered base and creates AP site
2. AP _____ removes faulty nucleotides and cleaves 5' end
3. AP _____ cleaves 3' end
4. DNA _____ fills the gap and DNA _____ seals it

What occurs in recombinational/postreplication repair?

replaces a damaged or missing section of DNA with the ____ or ____ sequences that may be present during replication

CRISPR/Cas9 is used to protect the bacterial chromosome against integration of ______ and ______ plasmids

Borrelia burgdorferi possess _____ genomes and _____ .

causative agent of _____ disease

What are bacteriophages?

bacterial viruses with a _____ or _____ genome usually protected by a _____ or _____ shell

What are the 2 ways in which bacteriophages infect?

1. _____ infection- replicate in large numbers and cause the cell to lyse

2. _____ state- integrate into host cell without killing

The E. coli bacteriophage ______ remains in a ______ state as long as the repressor protein is synthesized and prevents the phage genome from being excised to replicate and exit the cell

What are transposons?

a ____ sequence that can change its ____ within a genome

What occurs in transformation?

bacteria take up fragments of naked _____ and _____ them into their own genomes

The hepatitis B surface antigen is produced by ____ ____

An F⁺ E. coli cell conjugates with an F⁻ cell. Which structure allows the F⁺ cell to attach to the F⁻ cell?

A. Flagellum
B. Sex pilus
C. Endospore coat
D. Peptidoglycan bridge

In standard F⁺ × F⁻ bacterial conjugation, what is transferred to the recipient cell?

A. The entire donor chromosome
B. Only ribosomal RNA genes
C. A few chromosomal genes near oriC
D. A single strand of F plasmid DNA

Does standard F⁺ × F⁻ conjugation transfer chromosomal DNA?

A. No, only plasmid DNA is transferred
B. Yes, the entire chromosome is transferred
C. Yes, but only if the recipient already has an F plasmid
D. No DNA is transferred; only proteins are exchanged

After successful F⁺ × F⁻ conjugation, what usually happens to the recipient cell?

A. It remains F⁻ because plasmids cannot replicate
B. It becomes HFr because the chromosome is deleted
C. It becomes F⁺ because it receives the F plasmid
D. It loses its ability to undergo conjugation

The F plasmid contains genes required for which major process?

A. Antibiotic degradation
B. Sex pilus formation and conjugation
C. Endospore formation
D. Capsule synthesis

A bacterium has its F plasmid integrated into the bacterial chromosome. What is this cell called?

A. F⁻ cell
B. R plasmid cell
C. Competent cell
D. HFr cell

In an HFr cell, where is the F factor located?

A. Integrated into the bacterial chromosome
B. Floating separately in the cytoplasm
C. Inside the recipient bacterium only
D. Attached to the outer membrane as a pilus

An HFr cell conjugates with an F⁻ cell. Which DNA is most likely transferred first?

A. Random fragments of recipient DNA
B. Only the last portion of the bacterial chromosome
C. The leading portion of the integrated F factor followed by nearby chromosomal genes
D. Only circular double-stranded chromosomal DNA

In HFr × F⁻ conjugation, why does the recipient usually remain F⁻?

A. The recipient destroys all incoming chromosomal DNA
B. The entire F factor usually is not completely transferred
C. The F plasmid cannot initiate DNA transfer from oriT
D. The sex pilus prevents transfer of plasmid genes

Which outcome is most characteristic of HFr × F⁻ conjugation?

A. The recipient becomes F⁺ and receives no chromosomal genes
B. The donor becomes F⁻ after losing the entire chromosome
C. The recipient receives only an intact circular F plasmid
D. The recipient may integrate some donor chromosomal genes but usually remains F⁻

What occurs in generalized transduction?

incorporation of ____ sequences into phages are random due to a ____ error

What occurs in specialized transduction?

phages transfer _____ genes (not _____)

Isolates of S. aureus acquired the _____ resistant gene during a mixed infection with _____ _____

_____ _____ recognize a specific palindromic sequence and make a staggered cut that generates sticky ends

A researcher adds a plasmid to competent bacteria so the bacteria will take up and replicate the DNA. Which bacterial genetics process is being used?

A. Transduction

B. Transformation

C. Conjugation

D. Translation

A virus that infects bacteria is best described as which of the following?

A. Plasmid

B. Transposon

C. Operon

D. Bacteriophage

A bacteriophage accidentally carries bacterial DNA from one bacterium to another. What is this process called?

A. Transduction

B. Transformation

C. Conjugation

D. Replication

A newborn’s gut microbiome is shaped by complex carbohydrates in breast milk. Which bacterium is selected for?

A. Staphylococcus aureus

B. Escherichia coli

C. Enterococcus faecalis

D. Bifidobacterium infantis

Skin bacteria catabolize keratin, oils, and dead cells in which outer skin layer?

A. Stratum corneum

B. Stratum basale

C. Dermis

D. Hypodermis

Which molecules help maintain the structure of the bacterial chromosome?

A. Peptidoglycans

B. Sterols

C. Polyamines

D. Porins

Prokaryotes can couple transcription and translation because they lack which structure?

A. Cell wall

B. Nuclear membrane

C. Ribosome

D. Plasma membrane

Bacterial chromosomal replication begins at which specific sequence?

A bacterium exposed to UV light develops covalent links between adjacent pyrimidines. What caused this mutation?

A. Pyrimidine dimer formation

B. Base deamination

C. Transposon insertion

D. Plasmid loss

A patient with xeroderma pigmentosum has impaired repair of UV-induced pyrimidine dimers. Which repair pathway is defective?

A. Mismatch repair

B. Homologous recombination

C. Nucleotide excision repair

D. Base insertion repair

Which group of bacteria is naturally capable of taking up exogenous DNA?

A. E coli, Salmonella, Shigella

B. S pneumoniae, H influenzae type B, Neisseria

C. Mycoplasma, Chlamydia, Rickettsia

The bacterial sex pilus is a specialized form of which secretion system?

A. Type I

B. Type II

C. Type III

D. Type IV

Bacteria break down carbohydrates into sugars and short-chain fatty acids. What is this process called?

A. Fermentation

B. Transduction

C. Conjugation

D. Recombination

What is the universal intermediate of cell metabolism?

A. Lactate

B. Acetyl-CoA

C. Pyruvic acid

D. Citrate

Fermentation occurs under which condition?

A. Only with oxygen

B. Only in eukaryotes

C. Only during replication

D. Only without oxygen

Which statement best describes bacterial genetics?

A. Bacteria are haploid and often organize related genes into operons

B. Bacteria are diploid and often organize related genes into operons

C. Bacteria are haploid and lack gene regulation

D. Bacteria are diploid and use introns

What is transcription?

A. mRNA to protein

B. Protein to DNA

C. DNA to mRNA

D. DNA to protein

What is translation?

A. DNA to mRNA

B. mRNA to protein

C. Protein to DNA

D. RNA to DNA

Promoters and operators are usually located where relative to the gene/operon they regulate?

In negative control, genes are expressed unless turned off by what?

A. Repressor protein

B. Ribosome

C. Helicase

D. Primase

Which enzyme unwinds bacterial DNA at the origin during replication?

Which enzyme synthesizes primers to start bacterial DNA replication?

What does semiconservative DNA replication mean?

A. Each daughter DNA has one parental strand and one new strand

B. Both daughter DNAs are completely new

C. One daughter DNA is old and one is new

D. DNA is copied without using a template

Bacterial DNA synthesis occurs at growing replication forks and proceeds in which pattern?

A. Unidirectionally from plasmids

B. Only after cell division

C. Bidirectionally from the origin

D. Randomly across the chromosome

During bacterial growth, chromosome replication is initiated near which bacterial structure?

A. Capsule

B. Membrane

C. Flagellum

D. Ribosome

Which sequence correctly lists the phases of bacterial growth?

A. Death, lag, stationary, exponential

B. Stationary, death, lag, exponential

C. Exponential, lag, death, stationary

D. Lag, exponential, stationary, death

A repair system removes a damaged section of DNA and inserts a new DNA strand. Which repair type is this?

A. Direct repair

B. Fermentation

C. Excision repair

D. Conjugation

What does plasmid copy number measure?

A. Ratio of ribosomes to plasmids

B. Ratio of plasmid copies to chromosome copies

C. Ratio of phages to bacteria

D. Ratio of operons to genes

A mobile genetic element moves DNA from one location to another. What is it called?

A. Bacteriophage

B. Promoter

C. Operator

D. Transposon

Which are the 3 main mechanisms of bacterial horizontal gene transfer?

A. Transformation, conjugation, transduction

B. Transcription, translation, replication

C. Lytic, lysogenic, exponential

D. Fermentation, respiration, oxidation

A donor bacterium transfers DNA directly to a recipient through a sex pilus. Which process is this?

_____

During transduction, two genes are more likely to be cotransduced when they are located how?

A. On different chromosomes

B. Closer together

C. On separate plasmids

D. Farther apart

Scientists use a DNA carrier to deliver a gene into receptive bacteria. What is this carrier called?

A. Repressor

B. Operator

C. Cloning vector

D. Pyrimidine dimer

A patient with gram-negative sepsis has fever, hypotension, and inflammatory cytokine release due to a bacterial membrane component. Which toxin is responsible?

______. ______ is part of the gram-negative bacterial ______ membrane.

A secreted bacterial toxin is found to be a protein produced by either gram-positive or gram-negative bacteria. What type of toxin is this?

______

A researcher isolates a lipopolysaccharide complex from a gram-negative bacterium. Which toxin type is this?

Which part of LPS is mainly responsible for endotoxin toxicity?

____ ____

The terminal portion of LPS varies among bacterial strains and helps distinguish strains. What is this portion called?

____ ____

A toxin has an A component that causes toxicity and a B component that binds the host cell. What type of toxin is this?

_____

In an A-B exotoxin, which component binds to the host cell surface?

A. A component

B. B component

In an A-B exotoxin, which component performs the toxic activity inside the host cell?

A. A component

B. B component

Endotoxin binds CD14 on macrophages. Which mediators are released?

IL-____, IL-____, ____-____, ____ ____

A gram-negative infection activates complement through LPS. Which complement fragments are released as anaphylatoxins?

____ and ____

Why is endotoxin generally a poor target for toxoid-style vaccination?

A. It is only made by viruses

B. It has no toxic activity

C. It generates a weak antibody response

D. It is rapidly secreted from gram-positive cells

A bacterial toxin gene is found on a plasmid or bacteriophage rather than the chromosome. What type of toxin is most likely encoded?

_____

Which mobile genetic elements commonly encode exotoxin genes?

A. Ribosomes and operons

B. Capsules and fimbriae

C. Endospores and porins

D. Plasmids and bacteriophages

A toxin activates many T cells at once by linking MHC II on an APC to the T-cell receptor. What is this toxin called?

______

Superantigens differ from normal peptide antigens because they are not processed normally and instead bind _____ _____ and _____ directly

A patient develops shock after massive cytokine release from T-cell activation. Which toxin mechanism is most likely?

A. Botulinum toxin blocking ACh

B. Cytolysin destroying membranes

C. Superantigen causing massive T-cell activation

D. O antigen activating B cells

Which two organisms produce superantigens that can cause shock?

______ ______ and ______ ______

Most exotoxins are heat labile. What does this mean?

A. They are rapidly destroyed by heat

B. They become stronger after heating

C. They are made only during fever

D. They are identical to LPS

Which exotoxins are classic exceptions to the “heat-labile exotoxin” rule?

______ ______ and ______ ______ heat-stable toxin

A patient has flaccid paralysis after ingestion of a toxin that prevents acetylcholine release from vesicles. Which toxin is responsible?

A. Endotoxin

B. Superantigen

C. Botulinum toxin

D. Cytolysin

A burn patient develops a wound infection with a blue-green pigment and fruity odor. Which opportunistic pathogen is classically associated with burns?

_____ _____

Patients with cystic fibrosis are especially prone to chronic lung colonization by which organisms?

_____ _____ and _____ _____

Why do bacteria not express virulence factors all the time?

A. Virulence genes cannot be regulated

B. They only express them under specific conditions

C. All virulence factors are toxic to bacteria

D. Virulence factors are only found in viruses

Large genetic regions on a chromosome or plasmid that contain multiple virulence genes are called:

A. Operons

B. Ribosomes

C. Pathogenicity islands

D. Porins

A Salmonella virulence island is activated by acidic pH inside a macrophage phagocytic vesicle. Which pathogenicity island is this?

A. SPI-2

B. O antigen island

C. MSCRAMM island

D. Lipid A island

SPI-2 helps Salmonella survive intracellularly by promoting assembly of which device?

A. Type I secretion pump

B. Type II pili

C. Type IV conjugation pilus

D. Type III secretion device

A bacterium injects a pore-forming molecule into a host cell, then injects proteins through that pore. Which structure is being used?

A. Flagellum

B. Type III secretion device

C. Capsule

D. Ribosome

Many proteins injected by a type III secretion system help bacteria enter host cells by promoting what process?

A. Actin polymerization

B. Antibody secretion

C. Complement inhibition

D. Nuclear division

An organism causes disease mainly when host defenses are weakened or tissue barriers are damaged. What is this organism called?

A. Superantigen

B. Endotoxin

C. Opportunistic bacterium

D. Anaphylatoxin

Patients with AIDS are especially susceptible to intracellular bacteria such as which group?

_______

Systemic symptoms during bacterial infection are often caused by bacterial toxins and which host response?

A. Keratin production

B. Cytokine production

C. Lactose fermentation

D. Flagellar rotation

S aureus and S epidermidis are normal flora of which site and can cause infection after breaks in the barrier?

Indwelling catheters and IV lines increase risk of infection by skin flora mainly because they:

A. block antibody production

B. damage the spleen

C. reduce stomach acid

D. bypass the skin barrier

Natural openings such as the mouth, nose, anus, and respiratory/GI/GU tracts are protected by which defenses?

A. Mucus, cilia, lysozyme, and IgA

B. Lipid A, O antigen, and TNF

C. Plasmids, phages, and transposons

D. ATP, NADH, and FADH2

E coli remains attached to the urinary or intestinal epithelium instead of being washed away. Which bacterial factor explains this?

A. Endotoxin

B. Capsule

C. Adhesins

D. Botulinum toxin

Many bacterial adhesins are located on which surface structures?

A. Fimbriae

B. Ribosomes

C. Nucleoids

D. Inclusion bodies

Fimbrial adhesins commonly bind tightly to which host molecules?

A. Cytokines

B. Lectins

C. Antibodies

D. Complement proteins

Which organisms express adhesin proteins that are not located on fimbriae?

_____

_____ _____

_____ _____

A bacterium moves through the mucous layer toward epithelium. Which structure helps it swim?

_____

Which bacterial enzymes help digest the mucous layer so bacteria can approach epithelial cells?

______

C perfringens is normal microbiota but can cause gas gangrene under which condition?

____ oxygen

A patient develops rapid vomiting after eating food containing toxin already produced by bacteria. What type of toxin exposure is this?

A. Preformed toxin

B. Endotoxin only

C. Type III secretion

D. Pathogenicity island

Why do preformed toxins cause symptoms quickly?

A. They require bacterial replication first

B. They are already present before ingestion or exposure

C. They only activate complement slowly

D. They must integrate into host DNA

Exotoxins can include cytolytic enzymes and receptor-binding proteins. What do these toxins do?

A. Only form bacterial chromosomes

B. Alter cell function or kill cells

C. Become part of gram-negative membranes

D. Prevent all cytokine release

A toxin directly breaks down host cell membranes. What type of toxin is this?

______ toxin

A gram-negative bacterium releases LPS during infection, leading to macrophage activation. Which receptor complex is classically involved in recognizing LPS on macrophages?

A. CD14/TLR4

B. CD4/MHC II

C. CD8/MHC I

D. BCR/IgA

Nitric oxide released after endotoxin stimulation contributes most directly to which shock finding?

A. Bradycardia only

B. Vasodilation and hypotension

C. Increased platelet production

D. Increased gastric acid secretion

Which toxin type is most likely to be converted into a toxoid vaccine because it is a protein with strong immunogenicity?

Endotoxin or Exotoxin?

Which factor best explains why Pseudomonas can colonize cystic fibrosis lungs?

Impaired _____ _____ clearance

A device-associated S epidermidis infection persists despite antibiotics. Which bacterial structure most likely contributes?

_____

Which bacteria produce endotoxin?

A. Gram-positive bacteria only

B. Gram-negative bacteria only

C. Both gram-positive and gram-negative bacteria

D. Anaerobes only

High concentrations of endotoxin can activate which complement pathway?

A. Classical pathway

B. Lectin pathway

C. Alternative pathway

D. Terminal-only pathway

What is a typical bacterial capsule made of?

_____

A heavily encapsulated bacterium survives despite neutrophil exposure. What is the capsule mainly preventing?

A. Bacterial replication

B. Translation

C. Phagocytosis

D. Fermentation

Which set lists three ways bacteria evade antibody responses?

A. Antigenic variation, antibody inactivation, intracellular growth

B. ATP production, fermentation, replication

C. Capsule loss, ribosome loss, DNA loss

D. Complement fixation, opsonization, phagolysosome fusion

A bacterium repeatedly changes its surface antigens so previously made antibodies no longer bind well. Which immune evasion strategy is this?

A. Antigenic variation

B. Complement activation

C. Opsonization

D. Chemotaxis

A bacterium produces enzymes that destroy or inactivate host antibodies. Which immune response is it evading?

A. Antibody-mediated immunity

B. Complement-independent killing

C. T-cell receptor rearrangement

D. Macrophage cytokine release

Why does intracellular bacterial growth help evade antibodies?

Antibodies work best _____— intracellular bacteria are _____ from circulating antibodies.

Which bacterial structure limits complement access in gram-positive bacteria?

A. Thin LPS layer

B. Thick peptidoglycan

C. Long O antigen

D. Outer membrane porins

Which gram-negative structure can limit complement access in most gram-negative bacteria?

A. Long O antigen of LPS

B. Teichoic acid

C. Thick peptidoglycan

D. Spore coat

Why are Neisseria species an important exception when discussing long O antigen protection?

A. They lack peptidoglycan

B. They have LOS rather than full LPS with long O antigen

C. They are gram-positive

D. They cannot activate complement

Which strategy helps bacteria evade phagocytic cells by directly damaging those cells?

A. Producing enzymes that lyse phagocytes

B. Activating C3b opsonization

C. Increasing IgA binding

D. Promoting phagolysosome fusion

A bacterium avoids being engulfed by macrophages and neutrophils. Which evasion mechanism is this?

A. Inhibition of phagocytic uptake

B. Increased antigen presentation

C. Complement fixation

D. Cytokine neutralization

A bacterium is engulfed by a macrophage but survives by preventing phagosome-lysosome fusion. Which evasion strategy is this?

A. Blocking intracellular killing

B. Antibody class switching

C. Alternative complement activation

D. Anaphylatoxin release

A gram-negative bacterium releases endotoxin, activates macrophages, and triggers complement. Which final clinical outcome is most concerning at high endotoxin levels?

A. Hypotension and shock

B. Pure flaccid paralysis

C. No inflammatory response

D. Isolated antibody deficiency

E coli O157:H7 infection is classically associated with which serious complication?

A. Toxic shock syndrome

B. Pseudomembranous colitis

C. Hemolytic uremic syndrome

D. Gas gangrene

The production of type III secretion devices by Shigella flexneri is triggered by which environmental signal?

A. Oxygen tension

B. Acidic pH

C. High temperature

D. Bile salts

The production of type III secretion devices by Salmonella typhimurium is triggered mainly by which signal?

A. IgA binding

B. D-mannose binding

C. Fibronectin binding

D. pH

The SPI-2 pathogenicity island of Salmonella is activated in which location?

Acidic phagocytic vesicle inside a ______

A patient develops pseudomembranous colitis after antibiotic use. Which organism is most likely responsible?

____ ____

Which organism is inhaled, grows in the lungs, and is not typically spread person-to-person?

_____

In E coli, type 1 fimbriae bind which receptor molecule?

A. GM1 ganglioside

B. P blood group glycolipid

C. D-mannose

D. Fibronectin

E coli colonization factor antigen fimbriae bind which host receptor?

A. Collagen

B. Laminin

C. D-mannose

D. GM1 ganglioside

E coli strains that cause acute pyelonephritis use which adhesin and receptor pair?

A. Type 1 fimbriae; D-mannose

B. P fimbriae; P blood group glycolipid

C. MSCRAMMs; fibronectin

D. Colonization factor antigen; GM1 ganglioside

Streptococci and Staphylococcus aureus bind fibronectin, collagen, or laminin using which adhesin molecules?

A. MSCRAMMs

B. P fimbriae

C. Type 1 fimbriae

D. Colonization factor antigen

_____ and _____ use fimbriae to bind _____ cells before injecting pathogenic proteins.

Many proteins injected by a type III secretion device promote which host-cell process?

A. Antibody class switching

B. Complement activation

C. Sphingomyelin breakdown

D. Actin polymerization

How does Salmonella promote invasion through the GI tract?

_____ tight junctions of _____ cells

Rapid food poisoning from a preformed toxin is classically caused by which organisms?

____ ____

____ ____

Clostridium perfringens produces alpha-toxin. What is alpha-toxin?

A. IgA protease

B. Superantigen

C. Adenylate cyclase activator

D. Phospholipase C

Clostridium perfringens alpha-toxin breaks down which membrane component?

A. Peptidoglycan

B. Hyaluronic acid

C. Sphingomyelin

D. D-mannose

Cholera toxin increases cAMP by doing which of the following?

Permanently activating _____

Pertussis toxin increases cAMP by doing which of the following?

inactivating _____

A toxin cross-links the beta region of the T-cell receptor to MHC II on an APC. What type of toxin is this?

A. Endotoxin

B. Cytolysin

C. Superantigen

D. IgA protease

Toxic shock syndrome causes shock mainly through overwhelming release of which cytokines?

A. IL-4, IL-5, IL-13, IgE

B. IL-10, TGF-beta, IL-35, IgA

C. C3a, C3b, C5b, C9

D. IL-1, IL-2, IFN-gamma, TNF-alpha

Corynebacterium diphtheriae causes disease by inactivating which target?

____ ____ ____

Tetanospasmin from Clostridium tetani causes disease by which mechanism?

Cleaving _____ proteins to block _____ neurotransmitter release

Which triad best describes the major clinical effects of endotoxin?

A. Flaccid paralysis, diplopia, dry mouth

B. Fever, shock, DIC

C. Pseudomembranes, watery diarrhea, ileus

D. Spastic paralysis, lockjaw, opisthotonos

The Streptococcus pyogenes capsule is made of which substance?

A. Hyaluronic acid

B. Polyribosylribitol phosphate

C. Lipid A

D. Sphingomyelin

Why is the hyaluronic acid capsule of Streptococcus pyogenes useful for immune evasion?

It mimics human _______ tissue — this helps the bacterium _______ from immune recognition.

Which organism evades antibodies by antigenic variation and produces an IgA protease?

_____ _____

Protein A prevents opsonization and phagocytosis by binding which part of IgG?

_____ region

Which organism expresses Protein A?

_____ _____

Which Streptococcus pyogenes toxin causes cell membrane lysis?

A. Tetanospasmin

B. Diphtheria toxin

C. Streptolysin O

D. Cholera toxin

What is the main role of M protein in Streptococcus pyogenes virulence?

A. Prevents phagocytosis

B. Blocks acetylcholine release

C. Activates adenylate cyclase

D. Breaks down sphingomyelin

Mycobacterium species survive inside macrophages by blocking which process?

A. IgA secretion

B. Actin polymerization

C. D-mannose binding

D. Phagosome-lysosome fusion

Listeria monocytogenes escapes macrophage killing by doing which of the following?

A. Binding Fc region of IgG

B. Lysing the phagosome and escaping into the cytoplasm

C. Producing hyaluronic acid capsule

D. Activating the alternative complement pathway

Which test result best distinguishes Staphylococcus aureus from Staphylococcus epidermidis?

S aureus is _____ _____

What does coagulase do?

Converts _____ into fibrin to form a _____ barrier

Both cholera toxin and pertussis toxin increase cAMP. Which comparison is correct?

A. Cholera inactivates Gi; pertussis activates Gs

B. Cholera blocks adenylate cyclase; pertussis activates EF-2

C. Cholera cleaves SNARE; pertussis lyses membranes

D. Cholera activates Gs; pertussis inactivates Gi

A patient has rapid-onset vomiting after eating food left at room temperature. Why do symptoms appear so quickly with S aureus food poisoning?

A. The toxin is preformed in the food

B. The bacteria must invade macrophages first

C. The bacteria must form M protein first

D. The toxin requires phagosome-lysosome fusion

Salmonella and Yersinia bind M cells, inject proteins, and stimulate uptake into the host cell. Which bacterial tool makes this injection possible?

A. Coagulase

B. Type III secretion device

C. Protein A

D. IgA protease

Listeria and Shigella use actin polymerization mainly for which purpose?

______ within cells and spread to neighboring cells

A clinician is trying to maximize the yield of a blood culture in a patient with suspected bacteremia. What is the most important factor for success?

_____ of blood processed

Approximately how much blood should be collected from an adult for each blood culture?

A. 1 mL

B. 5 mL

C. 10 mL

D. 20 mL

How much blood should generally be collected per blood culture in children?

A. 1-5 mL

B. 5-10 mL

C. 20-25 mL

D. 30-35 mL

How much blood should generally be collected per blood culture in neonates?

A. 1 mL

B. 5 mL

C. 10 mL

D. 20 mL

A patient with pneumonia has bacteremia that appears only at certain times rather than constantly. What type of septicemia is this?

A. Continuous septicemia

B. Intermittent septicemia

C. Latent septicemia

D. Commensal septicemia

A patient with infective endocarditis or septic thrombophlebitis has persistent bacteria in the blood. What type of septicemia is most likely?

A. Intermittent septicemia

B. Transient septicemia

C. Continuous septicemia

D. Localized septicemia

Most clinically significant blood culture isolates are detected within what time frame?

A. 1-2 hours

B. 1-2 days

C. 5-7 days

D. 2-3 weeks

Even though most significant isolates appear early, blood cultures should be incubated for at least how long?

A. 12 hours

B. 24 hours

C. 5-7 days

D. 30 days

When CSF is collected from a suspected patient with ______, the specimen is concentrated by ______ and the sediment is used to inoculate bacteriologic media and prepare a ______ stain

After CSF is centrifuged in suspected meningitis, which part is used to inoculate bacteriologic media and prepare a Gram stain?

A. Supernatant

B. Sediment

C. Serum layer

D. Clot

For routine bacterial culture of CSF, what specimen volume is usually collected?

A. 0.1 mL

B. 1-5 mL

C. 20 mL

D. 50 mL

If mycobacterial meningitis is suspected, how much CSF should be collected?

As large a sample as possible — mycobacteria may be _____, so larger volume improves _____.

Most bacterial infections of the pharynx are caused by which organism?

_____ _____ _____

Which swab types are appropriate for collecting pharyngeal specimens?

A. Cotton or dacron

B. Wood or dacron

C. Dacron or calcium alginate

D. Metal or calcium alginate

Why should saliva contamination be avoided when collecting a throat swab for suspected group A strep?

____ bacteria can ____ growth of group A streptococci

Which specimens should be inoculated onto culture media immediately after collection before transport to the lab?

_____ _____ and _____ _____ — these organisms are fragile and require immediate inoculation.

Group A streptococci can be detected directly from a clinical specimen using which method?

_____ for _____ -specific antigen

Which set contains the most common bacterial causes of sinusitis?

_____ _____

_____ _____

_____ _____

_____ _____

A respiratory specimen has many squamous epithelial cells on microscopy. What does this suggest?

A. Excellent lower respiratory specimen

B. Saliva contamination

C. Mycobacterial infection

D. Bloodstream contamination

What procedure is required to make a specific microbiologic diagnosis of a middle ear infection?

A. Nasopharyngeal swab

B. Tympanocentesis

C. Throat culture

D. Blood culture

An abscess is drained and cultured. Where within the abscess are organisms most commonly replicating?

A. Surface crust

B. Base of the abscess

C. Surrounding normal skin

D. Necrotic center only

Clostridium difficile — it is a major cause of antibiotic-associated _____ and _____

What is the most sensitive and specific test for diagnosing Clostridium difficile infection?

____ ____ ____ ____ (____) detects C difficile toxin genes.

How long does it usually take to isolate and identify enteric pathogens by traditional methods?

A. 1-3 hours

B. 12 hours

C. 3 days

D. 2 weeks

A lab wants rapid detection of common bacterial, viral, and parasitic enteric pathogens directly from fecal swabs. Which method can detect them in 1-3 hours?

A. High-multiplex NAAT

B. Broth dilution

C. Blood agar hemolysis

D. Acid-fast stain

Which factor is required for aminoglycosides to enter bacterial cells?

A. Carbon dioxide

B. Oxygen

C. Capsule

D. IgA

Why are aminoglycosides generally ineffective against anaerobes?

A. Anaerobes destroy all ribosomes

B. Anaerobes lack oxygen-dependent drug uptake

C. Anaerobes always produce beta-lactamase

D. Anaerobes have no cell membrane

What is one advantage of broth dilution antibiotic susceptibility testing?

A. It requires no bacteria

B. Any antibiotic can be tested

C. It only detects viruses

D. It gives results without incubation

What is one limitation of broth dilution tests?

The manufacturer determines the _______ range and limited dilutions are _______.

Which organisms are alpha-hemolytic?

_____ _____

_____ _____

Which set contains beta-hemolytic organisms?

_____ _____

_____ _____

_____ _____

_____ _____

A stool specimen shows gram-negative bacteria arranged in S-shaped pairs. Which organism is most likely?

______

A blood agar plate shows a large outer zone of alpha-hemolysis with an inner zone of beta-hemolysis. Which organism classically produces this double zone?

_____ _____

Which specimen should be sampled from an abscess to maximize recovery of actively growing organisms?

_____ base because organisms most commonly _____ there.

A lab reports the MIC of an antibiotic for a bacterial isolate. What does this value tell the clinician?

The ____ drug concentration that stops ____ growth

What is the most common pathogen that causes swimmer's ear?

What organism is a gram-negative rod that has bipolar staining?

_____

What two classes of organisms are best detected using microscopy?

1. ____-____ rods

2. ____-____ cocci

A patient with infective endocarditis has persistently positive blood cultures throughout the day. What septicemia pattern is most likely?

A. Transient septicemia B. Intermittent septicemia C. Continuous septicemia D. Localized septicemia

Intermittent septicemia occurs in patients with _____ infections

Continuous septicemia occurs primarily in patients with _____ infections

To maximize recovery from an adult blood culture, how should the media bottles be inoculated?

A. One bottle, 20 mL

B. Two bottles, 5 mL each

C. Four bottles, 2 mL each

D. Two bottles, 10 mL each

After blood culture bottles arrive in the laboratory, at what temperature should they be incubated?

A. 25°C

B. 37°C

C. 4°C

D. 60°C

A CSF specimen is collected for suspected meningitis. Which handling instruction is most appropriate?

A. Freeze before transport

B. Refrigerate immediately

C. Avoid heat and refrigeration

D. Heat before plating

Which direct test can detect group A strep?

A. Immunoassay

B. Coagulase test

C. Oxidase test

D. Acid-fast stain

A clinician sends an oropharyngeal and nasopharyngeal culture to diagnose a lower respiratory infection. Why is this specimen inappropriate?

A. It is normally sterile

B. It misses oral flora

C. It is not useful

D. It requires refrigeration

A lower respiratory specimen has many squamous epithelial cells on microscopy. What does this indicate?

_____ contamination

A wound culture is needed, but the surface is covered with colonizing flora. What is the best collection method?

A. Surface swab only

B. Dried drainage sample

C. Deep aspiration

D. Surrounding skin swab

2 most common genital specimens?

_____ _____

_____ _____

How should you collect a feces sample?

____ pan not a swab

Two general forms of antimicrobial susceptibility tests are performed in the clinical laboratory:

_____ _____ tests and _____ _____ tests

A broth dilution test is one in which an antibiotic is prepared in a _____ medium and then then _____ with a standardized concentration of bacteria.

An agar diffusion test has bacteria spread over a surface, then a _____ with _____ is inserted into the surface.

If there is no _____ around the disk it is senstive to the _____ if there are bacteria it is resistant

A sputum smear is ordered because the clinician wants direct visualization of organisms often missed by routine Gram stain. Which class is microscopy especially useful for?

A. Anaerobic cocci

B. Viridans streptococci

C. Enteric bacilli

D. Acid-fast rods

A urethral discharge specimen is examined directly because the suspected organism is best detected microscopically. Which organism class fits this?

A. Gram-positive rods

B. Gram-negative cocci

C. Anaerobic bacilli

D. Spore-forming rods

To maximize recovery from an adult blood culture, how should the media bottles be inoculated?

A. One bottle, 20 mL

B. Two bottles, 5 mL each

C. Four bottles, 2 mL each

D. Two bottles, 10 mL each

A clinician wants blood cultures drawn exactly during a fever spike. Which statement is most accurate?

A. Timing is essential

B. Timing prevents contamination

C. Timing detects fungi only

D. Timing is less important

A resident asks for a Gram stain directly on blood from a septic patient. Why is this low yield?

Too _____ organisms — _____ blood usually has very low organism burden.

A CSF specimen from suspected meningitis is sitting unprocessed. Why is immediate processing important?

A. Some pathogens are labile

B. CSF rapidly clots

C. NAAT requires freezing

D. Anaerobes overgrow quickly

Which meningitis pathogens are especially labile in CSF specimens?

A. E coli, B fragilis

B. S aureus, Listeria

C. C difficile, Shigella

D. N meningitidis, S pneumoniae

A CSF specimen is sent to detect bacteria, viruses, and fungi. Which method is commonly used?

A. Coagulase test

B. NAAT

C. Oxidase test

D. Catalase test

A sterile abdominal fluid specimen may contain anaerobes. What handling error should be avoided?

A. Oxygen exposure

B. Prompt processing

C. Sterile collection

D. Anaerobic transport

Anaerobic culture handling is especially important in which infections?

A. Skin and urinary

B. Bone and joint

C. Intra-abdominal and pulmonary

D. Pharyngeal and sinus

Most bacterial pharyngitis is caused by which organism?

____ ____ Streptococcus

A pharyngitis culture is ordered for Bordetella pertussis. What should the lab expect?

A. Routine recovery

B. Special techniques

C. Anaerobic transport

D. Blood culture only

When collecting a throat swab for suspected group A strep, what contamination should be avoided?

A. Saliva

B. Exudate

C. Tonsillar tissue

D. Posterior pharynx

Which throat areas should be sampled for suspected bacterial pharyngitis?

A. Tongue and cheeks

B. Teeth and gums

C. Tonsils, posterior pharynx, exudate

D. Lips, palate, uvula

A rapid group A strep immunoassay is positive. What is the major strength of immunoassays?

A. High sensitivity

B. Low specificity

C. High specificity

D. Anaerobe detection

Current NAATs for group A strep are best described as having what major advantage?

A. Low contamination risk

B. High sensitivity

C. No transport needs

D. Detects all anaerobes

Which organisms are relatively resistant to drying during throat specimen handling?

A. GAS, C diphtheriae

B. B pertussis, gonorrhoeae

C. S pneumoniae, meningitidis

D. H influenzae, Moraxella

A child has suspected epiglottitis. Why should epiglottis culture be avoided?

A. Causes false negatives

B. Requires anaerobic transport

C. May obstruct airway

D. Detects normal flora only

A specific microbiologic diagnosis of sinusitis requires direct aspiration, anaerobic transport, and what else?

A. Fever-spike timing

B. Saliva dilution

C. Blood culture

D. Prompt processing

A blood culture grows Candida, while another grows E coli. Collectively, these bloodstream infections are called what?

A. Cellulitis B. Empyema C. Septicemia D. Abscess

A septic patient needs blood cultures before therapy. What collection strategy gives optimal yield?

A. Two to three samples

B. One large syringe

C. One aerobic bottle

D. Fever-spike sampling

A patient already received antibiotics before blood cultures. Why is this suboptimal?

A. Causes false gram stain

B. Inhibits organism recovery

C. Causes anaerobe overgrowth

D. Dilutes the specimen

Which organisms should be inoculated onto culture media immediately after collection?

A. GAS, C diphtheriae

B. S aureus, pneumococcus

C. H influenzae, Moraxella

D. B pertussis, N gonorrhoeae

A cavitary lung infection is suspected to be caused by an organism requiring extended incubation. Which organism fits this concern?

A. Moraxella catarrhalis

B. Streptococcus pneumoniae

C. Mycobacteria

D. Haemophilus influenzae

A branching, weakly acid-fast pulmonary pathogen is suspected. How should the lab handle incubation?

A. Stop at 48 hours

B. Extend incubation

C. Refrigerate only

D. Discard early

A child presents with fever, ear pain, and bulging tympanic membrane. Which set contains the most common otitis media pathogens?

A. Pneumococcus, H influenzae, Moraxella

B. Pseudomonas, S aureus, Candida

C. Gonorrhoeae, Chlamydia, Treponema

D. Mycobacteria, Nocardia, Legionella

Otitis externa culture is needed after treatment failure. What is the best specimen?

A. Middle-ear aspirate

B. Nasal swab

C. Ear-area scraping

D. First-void urine

A patient has suspected bacterial conjunctivitis. How should the initial eye surface specimen be collected?

A. Swab before anesthetic

B. Swab after anesthetic

C. Direct eye aspiration

D. First morning urine

A corneal ulcer is suspected after contact lens use. After surface swabbing, what specimen may be needed?

A. Corneal scraping

B. Midstream urine

C. Nasopharyngeal swab

D. Blood culture

Endophthalmitis is suspected after eye surgery. What is the proper intraocular specimen method?

A. Surface swab

B. Corneal scraping

C. Direct aspiration

D. Eyelid scraping

Why are ocular infection cultures often difficult to interpret?

A. Excessive specimen volume

B. Few organisms present

C. Constant anaerobe overgrowth

D. Routine blood contamination

An ocular specimen may contain Neisseria gonorrhoeae. What special lab need should be considered?

A. Specialized culture media

B. Extended mycobacterial incubation

C. Anaerobic urine preservative

D. Biphasic blood bottles

An ocular infection is suspected to be caused by Chlamydia trachomatis. Which culture approach is needed?

A. Blood agar only

B. Tissue culture cells

C. Anaerobic broth

D. Routine urine agar

A urine culture is collected for suspected cystitis. Why is the first portion of urine discarded?

A. It lacks bladder organisms

B. It contains urethral flora

C. It kills anaerobes

D. It prevents pyuria

A urine specimen cannot be plated immediately. What should be done?

A. Leave at room temperature

B. Warm to 37°C

C. Refrigerate or preserve

D. Freeze before transport

Why should urine culture transport not be delayed?

A. Pathogens grow in urine

B. Urine rapidly clots

C. NAATs become nonspecific

D. Pyuria disappears instantly

A urine culture plate is inoculated with a calibrated loop. What volume is typically used?

A. 1–10 µL

B. 0.5–1 mL

C. 5–10 mL

D. 20–30 mL

Why is a measured urine volume plated for culture?

A. Quantify organism burden

B. Prevent oxygen exposure

C. Detect exotoxin genes

D. Remove urethral cells

A symptomatic patient has pyuria but only low colony counts. How should this be interpreted?

A. Always contamination

B. Potentially significant

C. Reject automatically

D. Ignore without testing

Most labs evaluating sexually transmitted urethritis focus on which pathogens?

A. Gonorrhoeae and trachomatis

B. Pneumococcus and Moraxella

C. Mycobacteria and Nocardia

D. Pseudomonas and Staph

A man has dysuria and urethral discharge. Which urine specimen is preferred for GC/CT NAAT?

A. Midstream urine

B. First-void urine

C. Refrigerated catheter urine

D. Discarded first portion

A woman has suspected cystitis rather than urethritis. Which urine collection best reduces urethral contamination?

A. First-void urine

B. Midstream urine

C. Eye aspirate

D. Corneal scraping

A patient has a painless genital chancre, but the suspected organism cannot be cultured. Which diagnostic approach is appropriate?

A. Stool culture

B. Darkfield or serology

C. Blood agar culture

D. Broth dilution

A spirochete is suspected in a syphilis lesion, but brightfield microscopy is negative. Why can this happen?

A. Too thick

B. Nonmotile organism

C. Intracellular growth

D. Too thin

A clinician collects fluid from a suspected syphilitic chancre for microscopy. When should the exam be performed?

A. After refrigeration

B. After 24 hours

C. At collection

D. After freezing

A stool specimen for enteric culture sits unprocessed for hours. Which change can harm pathogens such as Shigella?

A. Alkaline shift

B. Acidic shift

C. Oxygen depletion

D. Bile dilution

Why should stool specimens be transported promptly for culture?

A. Prevent toxic pH changes

B. Increase bacterial metabolism

C. Preserve urine volume

D. Prevent antibody loss

A rectal swab is submitted for routine stool culture. Why is this specimen poor?

A. Too anaerobic

B. Too acidic

C. Inadequate pathogen recovery

D. Excessive stool volume

Transport of a stool specimen will be delayed. Which medium is appropriate?

A. Chocolate agar

B. Cary-Blair medium

C. Thioglycolate broth

D. Loeffler medium

Which preservative can be used for delayed stool transport?

A. Phosphate-glycerol buffer

B. Sheep blood agar

C. Mueller-Hinton agar

D. Sabouraud agar

A patient has rapid vomiting after reheated rice. Stool culture is negative for the causative organism. Why?

A. Intracellular infection

B. Preformed toxin disease

C. Slow anaerobic growth

D. Acid-fast organism

Which organisms are not expected in stool because illness is caused by preformed food toxin?

A. Shigella, Salmonella

B. Vibrio, Campylobacter

C. S aureus, B cereus

D. Giardia, Cryptosporidium

A clinician strongly suspects a specific unusual enteric pathogen. What should be done for optimal testing?

A. Notify the laboratory

B. Delay specimen transport

C. Request rectal swab

D. Avoid preservatives

Why can culture-based enteric pathogen identification take several days?

A. Feces lacks bacteria

B. Feces has mixed flora

C. Culture is always anaerobic

D. NAAT blocks growth

Which method is becoming preferred for broad enteric pathogen detection?

A. High multiplex NAAT

B. Gram stain only

C. Blood culture

D. Broth dilution

High multiplex NAAT can detect common enteric pathogens directly from fecal swabs in what time?

A. 24–48 hours

B. 1–3 hours

C. 3–5 days

D. 2–4 weeks

High multiplex NAAT is especially useful for pathogenic E coli because it can distinguish it from what?

A. Normal enteric E coli

B. C difficile toxin

C. Acid-fast rods

D. Anaerobic lung flora

In a broth dilution test, antibiotics are prepared how?

A. On paper disks

B. In dilution series

C. On corneal scrapings

D. Inside blood bottles

Broth dilution testing is used to determine which value?

A. O antigen

B. Toxin titer

C. MIC

D. Capsule thickness