Microbiology Exam 2 Flashcards
Environmental factors with the greatest impact on microbes are
Nutrients, Temperatures, pH, Amount of water available, atmospheric gases, Light, pressures, and other organisms
+ Which elements are macronutrients?
+ Which are micronutrients?
What is a growth factor?
an organic nutrient(amino acid, nitrogenous base, or vitamin) that cannot be synthesized and must be provided as a nutrient
What are the two nutritional types?
Autotroph-chemoautotroph and photoautotroph
Heterotroph-saprobe (dead organisms) and parasite
+ What is the carbon source for autotrophs?
organisms that obtain inorganic source such as co2 as its carbon source and is not nutritionally dependent on other organisms for their survival
+ What is the carbon source for Heterotrophs?
nutritionally dependent on organic source from other organisms.
What is Microbial Cells?
Microbial cells must take in nutrients from their
surroundings by transporting them across the cell
+ What are examples of active transport?
molecules that are taken into the cell by a process that requires energy
( carrier mediated active transport, group, translocation, phagocytosis, pinocytosis )
+ What are passive transport?
involves the natural movement of substances down a concentration gradient and requires no additional energy
( simple or facilitated diﬀusion )
+ What happens to cells in hypertonic solutions?
cells shrink or crenate (distorted)
+ What happens to cells in hypotonic solutions?
cells swell and burst (lyse)
What happens to cells in isotonic solutions?
no net diﬀusion of water
rate of diffusion are equal
+ What is the name of a cell that requires a high salt environment?
What is Obligate halophile?
organisms that have adapted to high salt concentrations (15-20% salt) that the require them for growth
What is Simple diﬀusion?
molecules readily pass through the cell membrane
What is Facilitated diﬀusion?
molecules pass through the cell membrane via a carrier protein
+ What is phagocytosis?
Phagocytosis is considered cell “eating” (brings in solid to the cell)
+ What is pinocytosis?
Pinocytosis is considered cell "drinking" (bring in liquid to the cell)
+ What is Mesophiles?
organisms that thrives between temperature of 10-50 degree Celsius.
+ What is Thermophiles?
organisms that thrives between temperature of 45-80 degree Celsius.
+ What is psychrophiles?
organisms that thrives between temperature of -20-15 degree Celsius.
+ What are Strict anaerobes?
Anaerobe that cannot grow in the presence of oxygen (O2)
+ What are Aerotolerant anaerobes?
anaerobe that cannot use oxygen (O2) but is not injured by it
+ What are Facultative anaerobes?
aerobe capable of living without oxygen (O2)
+ What are microaerophiles?
requires a small amount of O2 but does not grow under anaerobic conditions
+ What are acidophiles?
organism that thrives in pH below 7pH (acidic environment)
+ What are Alkalinophiles?
organism that thrives in pH above 7pH (alkaline environment)
+ What are Neutrophiles?
organism that thrives in 7pH (neutral environment)
What are barophiles?
organism that thrives in high barometric pressure
+ What are examples of symbiotic relationships?
organisms that live in close nutritional relationships; required by one or both members (Mutualism, Commensalism, Parasitism all dependent on one another for survival)
What is a mutualism relationship?
Obligatory dependent; both members benefit
What is a commensalism relationship?
The commensal (bacteria living in another bacteria) benefits; other members are not harmed.
What is a parasitism relationship?
Parasite is dependent and benefits; the host is harmed.
+ What are examples of nonsymbiotic relationships?
organisms that are free-living; relationships not required for survival (Synergism and Antagonism)
What is Synergism?
Members cooperate and share nutrients
What is Antagonism?
Some members are inhibited or destroyed by others.
What is Quorum sensing?
an interaction among members of abioﬁlm that results in a coordinated reaction such as secreting an enzyme
+ What is the name of the process that bacteria go through to reproduce?
+ Be able to label the parts of a growth curve.
-Lag Phase-period of adaption (adjustment)
-Experimental Growth Phase-growth balances out
-Stationary Phase-population enters survival mode
-Death Phase-nutrients run out, and death occurs
What is metabolism?
the sum of all chemical and physical activities in a cell
is made possible by enzymes that speed up chemical reactions by lowering the energy of activation
+ What is catabolism?
Large molecules that are degraded back into a smaller molecule
+ What is anabolism?
reactions that convert smaller molecules into larger molecules
+ What is substrate specificity?
Enzymes that has a specific substrate and will only recognize its own type to bind with. (Lock and Key)
+ How are enzyme names similar?
They all end with “ase”
How do enzyme functions relate to their names?
Their name states what they do. i.e Oxidase-add electron to "Oxygen". Nitrate Reductase-reduce nitrate to nitrites.
What is Hydrolysis?
reactions that involves addition of water to break bonds
What is Condensation?
reactions that involve releasing water to form bonds
+ Be able to recognize when a molecule has been oxidized or reduced.
Oxidized=remove of hydrogen-loss of (H+)
Reduced= Adding of Hydrogen-Gain (H+)
What is denaturing?
the term for loss of three-dimensional structure of a protein
Enzymes are general targets for what physical and chemical agents?
– Heavy metals
+ How does competitive inhibition work?
a substrate-like molecule binds the enzyme and blocks it from binding to its natural substrate
+ How does noncompetitive inhibition work?
the regulator molecule does not bind the same
site as the natural substrate
What is Endergonic reaction?
Endergonic reactions consume energy use(ATP)
What is Exergonic reaction?
Exergonic reactions release energy create(ATP)
+ What is the difference between endergonic and exergonic reactions?
Endergonic reactions consume energy use(ATP) and Exergonic reactions release energy create(ATP)
+ How many ATPs and NADHs does glycolysis yield per glucose?
2 ATP and 2 NAD's
+ During glycolysis, glucose is converted to how many pyruvates?
2 Pyruvates (each pyruvates goes through the steps and Crebs-cycle once)
+ The Krebs cycle yields how many ATPs and how many reduced electron carriers (per two pyruvate)?
2 ATP and 8 Electron
+ In which location of the cell does The Krebs cycle occur?
+ In which location of the cell does glycolysis occur?
+ What is the name of the enzyme that produces ATP in the electron transport chain?
+ What occurs during the light-dependent reactions of photosynthesis
photons are absorbed by chlorophyll, water is split by photolysis, oxygen is released, and electrons released drive photophosphorylation
(H+ + ADP + ATP synthase -> ATP)
LIGHT IS NEEDED
+ What occurs during the light-independent reactions of photosynthesis?
(Calvin cycle) use ATP to ﬁx CO2 to a carrier (RIBULOSE-1,5-BISHOPHATE) and convert it to glucose in a multi-step process.
LIGHT DOESNT MATTER
What does genes provide?
provide the information needed to construct proteins (enzymes)
What is DNA?
long molecule in the form of a double helix
What is Nucleotides?
the basic structural unit of DNA that are composed of
– Deoxyribose (sugar)
– Nitrogen base(A,T,C,G)
Genetics is the study of heredity and can be studied at several levels. What are the layers?
+ DNA replication is semiconservative because ?
Each daughter cell contains a parent strand and a
newly-synthesized complementary strand
What is RNA?
contains codons (groups of three consecutive
nucleotides)that pair with anticodons on the tRNA to specify which amino acid to assemble on the ribosome during translation
+ How is RNA different from DNA?
Single-stranded instead of double-stranded
Contains uracil (U) instead of thymine (T)
Contains ribose instead of deoxyribose
+ What are the three types of RNA?
mRNA, tRNA, rRna
+ What are the functions of mRNA?
message based on the DNA sequence, contains codons
+ What are the functions of tRNA?
brings amino acids to the ribosome during
translation, contains anticodons
+ What are the functions of rRNA?
major part of the ribosome
What does RNA contain?
contains codons (groups of three consecutive nucleotides that pair with anticodons on the tRNA to specify which amino acid to assemble on the ribosome during translation
What is transcription?
the process by which DNA is used to produce RNA
occurs when RNA polymerase copies the template strand of DNA
What is translation?
(RNA->Protein) occurs when the RNA is used to direct the synthesis of proteins on the ribosome
– Begins at a “start” codon (AUG)
– Ends at a “stop” codon (UAA, UAG, or UGA)
+ What are the parts of an operon?
promoter, operator and terminator
+ How is transcription affected when a repressor is bound to an operator?
When the repressor is bound to the operator, transcription does not occur BUT When the repressor is not bound to the operator, transcription occurs.
In procaryotes, when does transcription and translation occur?
at the same time(both occur in the cytoplasm)
In eukaryotes, when does transcription and translation occur?
they occur separately and in diﬀerent parts of the cell (transcription occurs in the nucleus and
translation occurs in the cytoplasm)
• In eukaryotes the mRNA must also be processed before translation can occur.
• Contains introns (intervening sequences) and exons (expressed sequences), where the introns must ﬁrst be removed
What sequence contains the genes?
The sequence between the “operator” and “terminator” contains the genes
+ What are the parts of an Operon?
Promotor, Operator, Terminator, and Genes
+ What is terminator?
where transcription stops
+ What is promotor?
where RNA polymerase binds
+ What is operator?
where repressor molecules bind
What prevents the repressor from binding the operator?
An inducer molecule
+ Under what conditions is the Lac operon switched on?
In the absence of glucose,(even if lactose is present)lactose can be broken down and used for energy; certain enzymes are required for this process and are encoded by the Lac Operon
Some operons are repressible – NORMALLY ON but can be turned oﬀ. Describe one.
The Tryptophan Operon: Usually on and making tryptophan; when enough tryptophan is present the operon is turned oﬀ
Mutations are changes in the genetic code.
How can we detect changes?
Mutations can be detected using selective
media and the replica plating technique.
+ What is a missense mutation?
change that leads to placement of a diﬀerent amino acid by the ribosome (cause amino acid to change)
+ What is a Nonsense mutation?
changes a normal codon into a stop codon (premature stopping)
+ What is a silent mutation
alters a base but does not change the amino acid and thus has no eﬀect
+ What is a back mutation
a gene that has undergone mutation reverses to the non-mutated state (mutated genes revert back to its original state)
Many mutations can be corrected using enzymes found in the cell, what is DNA photolyase?
ﬁxes UV damage
Many mutations can be corrected using enzymes found in the cell, what is Excision repair enzymes?
ﬁxes mismatched bases
+ Why are Ames tests used?
measures the mutagenicity of chemicals by their ability to induce mutations in bacteria
+ What is conjugation?
bacterial mating where DNA is transferred from one cell to another via the pilis
+ What is Transformation?
the transfer of naked DNA from the environment to the bacterial cell through special receptors on the cell surface
+ What is Transduction?
a process where viruses insert bacterial DNA into bacteria accidentally in nature
-We can also do this in the lab by placing DNA into a bacterial virus and then infecting bacterial cells
+ What are transposons?
Also called “jumping genes” are segments of DNA that regularly move to diﬀerent places within the genome of a cell generating mutations and variations in chromosome structure
Know Genome viruses
viruses can be double-stranded or single-stranded, and can be RNA or DNA
Know DNA and RNA viruses
DNA viruses tend to replicate in the nucleus while
RNA viruses tend to replicate in the cytoplasm
What is decontaminant?
procedures involve the destruction or removal of contaminants
+ What is a contaminant?
deﬁned as microbes present at a given place and time that are undesirable or unwanted
+ What is sterilization?
a process that destroys or removes all microbes, including viruses
What is Bactericidal?
chemicals that destroys bacteria
What is Bacteriostatic?
agents that temporarily prevent growth of microbes
What is Germicidal chemicals?
chemicals that will kill any pathogenic microorganism
+ What is the difference between microbicidal and microbistatic agents?
microbicidal destroys bacterias while microbistatic agent temporarily prevent growth of microbes.
I.E Microbistatic is similar to a fridge (coolness slow bacteria growth)
+ What are the cellular targets of antimicrobial agents?
They work by targeting either
- Cell wall synthesis and break the cell wall down
– Membrane permeability and lyses the lipids
– Protein and nucleic acid synthesis and function, it denature proteins
+ What is the temperature/pressure combination for an autoclave?
Temperature 120C @ 15psi, 20 minutes
+ What is the outcome of pasteurization?
subjects liquids to temperatures below 100C and is used to lower the microbial load in liquids
A widely used method is the ﬂash method
• 71.6C for 15 seconds
Another method is the batch method
• 66C for 30 minutes
+ What is the outcome of boiling?
Boiling water at 100C for 30 minutes disinfects, but does not sterilize
+ What is the outcome of incineration?
Incineration can be carried out using a Bunsen
burner or incinerator
• Temperatures range between 800C to 6500C
+ What is the outcome of desiccating?
Drying and desiccation lead to (often temporary) metabolic inhibition by reducing water in the cell (drying not killing all bacterias)
+ What is the outcome of radiation?
Energy in the form of radiation can be used for
– Works by killing microbes without heat
+ What is the outcome of filtration?
Filtration involves the physical removal of
microbes by passing a gas or liquid through a
• Air and heat-sensitive liquids can be sterilized using this method
What is ionizing radiation?
causes breaks in DNA (xrays)
What is Nonionizing radiation?
Creates dimers in DNA stopping communication (UV-Light)
+ What are Antiseptics?
destruction of vegetative cells on animate (living object/surfaces) surfaces
+ What are Sanitizers?
clean inanimate (nonliving object/surfaces) objects using soap and degerming agents to achieve a “safe level” of microbes
(removes microorganisms to “safe levels or standards”)
+ What are Degermers?
physically remove surface oils, debris, and soil
from skin to reduce the microbial load
+ What are disinfectants?
destruction of vegetative cells on inanimate (nonliving object/surfaces)surfaces
(destroys vegetative pathogens but not bacterial endospores)
+ What components of the cell are affected by chlorine/iodine?
Chlorine disrupt disulﬁde bonds in PROTEINS and
can be sporicidal
– Iodine works similarly to chlorine
+ What components of the cell are affected by phenolics
Phenolics disrupt CELL MEMBRANES and precipitate PROTEINS
+ What is biphenols?
Bisphenols are mild forms for disinfection and
+ What components of the cell are affected by chlorhexidine
surfactant and a protein denaturant (CELL MEMBRANE)
Solutions are found in skin degerming agents for preoperative scrubs, skin cleaning, and burns
+ What components of the cell are affected by alcohol?
Ethyl and isopropyl alcohol, in concentrations of 50-90% act as surfactants
– Dissolve membrane LIPIDS and denature proteins
+ What components of the cell are affected by hydrogen peroxides?
Hydrogen peroxide damages protein and DNA, while also decomposing to O2 gas which is toxic to anaerobes
What components of the cell are affected by Detergents?
Detergents, known as quaternary ammonium compounds (quats) act as surfactants that alter membrane permeability
+ What components of the cell are affected by soaps?
Soaps have little microbicidal activity but, rather, function by removing grease and soil
that contain microbes
+ What components of the cell are affected by heavy metals?
Heavy metals inactivate proteins