Microbiology First Exam
What benefits do microorganisms provide?
Decompose organic wastes
Producers in the ecosystem by photosynthesis
Produce industrial chemicals (ethyl alcohol and acetone)
Produce fermented foods such as vinegar, cheese and bread
Food preservation, flavor, biochemical recycling, vitamins
What harm do microorganisms cause?
What is genus?
The first name in the scientific bi-nomenclature that is capitalized.
What is specific epithet (species)?
The second name in the scientific bi-nomenclature that is not capitalized.
Who established the system of scientific nomenclature?
Carolus Linnaeus in 1735
What does a scientific name tell us about the organism for which it is named?
It may be descriptive of the organism or it may honor a scientist.
What are the main groups of microorganisms?
Who identified the 3 domains of microorganisms and when?
Carl Woese in 1978
By what method are microorganisms classified in the 3 domains?
It is based on ribosome RNA (protein factory).
What are the characteristics of bacteria?
Peptidoglycan cell walls
Use organic chemicals or photosynthesis for energy
What are the characteristics of archaea?
Live in extreme environments
Include: methanogens, extreme halophiles, extreme thermophiles
What are the characteristics of fungi?
Chitin cell walls
Use organic chemicals for energy
Includes molds, mushrooms and yeast
What is mycelia?
What is hyphae?
The filaments that make up mycelia.
Which type(s) of fungi have mycelia?
Molds and mushrooms
What are the characteristics of protozoa?
Absorb or ingest organic chemicals
May be motile via pseudopods, cilia, or flagella
What are the characteristics of algae?
Cellulose cell walls
Use photosynthesis for energy
Produce molecular oxygen and organic compounds
What are the characteristics of viruses?
Consist of DNA or RNA core
Core is surrounded by a protein coat
Coal may be enclosed in a lipid envelope
Are replicated only when they are in a living host cell
What is classified under domain eukarya?
Who described "little boxes" or "cells" and is credited with the beginning of the cell theory of life (all living things are composed of cells)?
Robert Hooke in 1665
Who was the first to observe live mircroorganisms 'animalcules" and is called the "Father of Microbiology"?
Antoni van Leeuwenhoek in 1673
Who heated broth in open flasks with s-shaped necks disproving the spontaneous generation theory?
Louis Pasteur in 1861
What is biogenesis?
All cells arise only from preexisting cells.
What is aseptic technique?
The most important techniques that all microbiologists use. The methods that prevent contamination by unwanted microorganisms.
What is Pasteurization?
Heating which kills pathogens but does not damage the food (milk). This application of a high heat for a short time.
What is the difference between sterilization and Pasteurization?
Sterilization kills the pathogen and the host; Pasteurization only kills the pathogen.
Who showed that a silkworm disease was caused by a fungus?
Agostini Bassi in 1835
Who believed that another silkworm disease was caused by a protozoan?
Louis Pasteur in 1865
Who advocated handwashing to prevent transmission of puerperal fever from one OB patient to another?
Ignaz Semmelwise in 1840s
Who used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur's work showing microbes are in the air, can spoil food and cause animal disease?
Joseph Lister in 1860s
Who provided proof that a bacterium causes anthrax and provided the experimental steps used to prove that a specific microbe causes a specific disease?
Robert Koch in 1876
What are Koch's postulates?
Pathogen must be present in all cases of disease
Pathogen must be isolated and grown in lab in pure culture
Pathogen from pure cultures must cause disease when inoculated into healthy, susceptible lab animals
Same pathogen must be isolated from the diseased lab animal
Why are Koch's postulates used?
To look for the cause of a specific disease
Who inoculated a person with cowpox virus and as a result, the person was protected from smallpox.
Edward Jenner in 1796
What is the protection from a disease called?
Who discovered the first antibiotic?
Alexander Fleming in 1928
What is the name of the first antibiotic?
Penicillin - made from the fungus Penicillium
When was penicillin tested clinically and mass produced?
In the 1940s
What is total magnification?
Objective lens x ocular lens
What is resolution?
The ability of the lenses to distinguish two points.
In a microscope, what is either reflected, refracted or absorbed?
Why is immersion oil used?
To keep light from bending
What kind of microscope has only one lens?
A simple microscope
In which type of microscope is the image magnified by the objective lens and then again by the ocular lens?
A compound microscope
What type of microscope shows a dark image against a brighter background?
A Bright-field mircroscope
True or false. In the bright field microscope, light reflected off the specimen does not enter the objective lens.
Which concept accentuates diffraction of the light that passes through a specimen and where direct and reflected light rays are combined at the eye?
Which concept uses UV light and cells may be stained with fluorescent dyes (fluorochromes)?
Where is fluorescence microscopy used regularly?
In the hospital
Using the fluorescent microscopy, how can you tell if a Syphilis test is positive or negative?
Green means positive and yellow means negative
What does an electron microscope use for illumination?
Electrons because they have shorter waves lengths and allow for greater resolution.
What are the two types of electron microscopes?
TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope)
Which electron microscope displays an image produced by electrons which are emitted from the surface of the object creating a 3 dimensional structure?
Scanning Electron Microscope
Which electron microscope have electrons that pass through a thin section of the specimen?
Transmission Electron Microscope
Which electron microscope can view specimens that have been stained with heavy metal salts and show a two dimensional structure?
Transmission Electron Microscope
What is fixation?
A process by which internal and external structures of a cell are preserved.
What is heat fixation?
Fix an air-dried thin film (smear) by passing through a flame
Why is fixation used?
To attach the microbes to the slide and to kill the microbes
In an ionic stain, basic dyes have a chromophore that is a ______.
In an ionic stain, acid dyes have a chromophore that is an _________.
When only one staining agent is used, this type of staining is called ________.
How do differential stains work?
It divides bacteria into separate groups based on staining properties.
What type of stain traps crystal violet-iodine complex due to a thick layer of peptidoglycan cell wall?
When lipids in the cell wall are dissolved by the ethanol, allowing crystal violet-iodine complex to escape, what type of stain does it depict?
What is the most important staining procedure and who is it named for?
Gram stain, Dr. Christian Gram in 1884
In the Gram Stain, which is the primary stain?
In the Gram Stain, which is the counterstain?
In the Gram Stain, which is the mordant?
In the Gram Stain, which is the decolorizing agent?
Name the steps in the Gram Stain
1. Crystal Violet - 1 minute 2. water 3. Iodine - 1 minute 4.Alcohol - 10-20 secs 5.water 6.Safranin - 1 minute 7.water 8.Dry lens - DO NOT RUB!
In Gram+, what is the color stain after the mordant is applied?
In Gram-, what is the color stain after the counterstain is applied?
Why is an acid-fast stain used?
To stain Mycobacterium, which have high mycolic acid content (waxy)
What is the counterstain used in acid-fast staining?
What are cells called that retain a basic stain in the presence of acid-alcohol?
What is the evolutionary history of a group of organisms?
In the Three-Domain system, what does bacteria have that the other domains do not have?
Mitochondria and chloroplast
What does the fossil record tell us?
What does rRNA sequencing tell us?
In Eukarya domain, which type is multicellular but has no cell wall and is chemoheterotrophid?
Which Eukarya is multicelluar but with a cellulose wall and usually phototutotrophic
Which kingdom is unicellular or multicellular; has chitin cell walls and may develop from spores or hyphal fragments?
Which kingdom is considered the "catch all" for eukaryotic organisms that don't fit in any other kingdom?
What is a clone?
When a population of cells are derived from a single cell
What characteristics do all cells have in common?
Basic shape - spherical, cubical, cylindrical
Internal content - cytoplasm, surrounded by a membrane
DNA Chromosome(s), ribosomes, metabolic capabilities
What are the two basic cell types?
Eukaryotic and Prokaryotic
What are the characteristics of a prokaryote?
One circular chromosome, not in a membrane
Peptidoglycan cell walls
What are the characteristics of a eukaryote?
Paired chromosomes, in a nuclear membrane
Polysaccharide cell walls
What are the basic shapes of a cell?
Spherical, cubical and cylindrical
What are the arrangements of cells?
Pairs: diplococci. diplobacilli
Chains: streptococci, streptobacilli
What are the unusual shapes of cells?
Are most bacteria monomorphic or pleomorphic?
Monomorphic, only a few are pleomorphic
What is a glycocalyx?
A capsule, slime layer, or extracellular polysaccharide) is a gelatinous polysaccharide and or polypeptide covering
Outside cell wall
A capsule is neatly organized
A slime layer is unorganized and loose
Extracellular polysaccharide allows cell to attach
What does the glycocalyx (capsules) do?
Enable adherence to surfaces
Prevent desiccation (dryness)
Which are more likely pathogen, much more virulent and more stable to create more bacteria?
Cells with capsules or glycocalyx
Explain the movement of motile cells?
Clockwise - toward food
Counterclockwise - away from toxins
What is fimbriae?
Fine, proteinaceous, hair-like bristles from the cell surface
Function in adhesion to other cells and surfaces
What are pili?
Pili are used to transfer DNA from one cell to another called conjugation
Found only in Gram negative cells
What is conjugation?
The transferring of DNA via pili
What is the function of the cell wall?
Prevents osmotic lysis
Made of peptidoglycan (in bacteria)
Give shape to bacteria
Protection of the cell
What is peptidoglycan?
Polymer of disaccharide (NAG) & (NAM)
Linked by polypeptides
Describe Gram-positive cell wall
Teichoic acids: Lipoteichoic acid links to plasma membrane; Wall teichoic acid links to peptidoglycan
In acid-fast cells, contains mycolic acid
May regulate movement of cations
Polysaccharides provide antigenic variation
Describe the Gram-negative cell wall
No teichoic acids
In which type of cell wall can the glycin bridge be found?
Gram-Positive cell walls
Describe the Gram-Negative Outer Membrane
Lipopolysaccharides, lipoproteins, phospholipids
Forms the periplasm between the outer membrane and the plasma membrane
Protection from phagocytes, complement, antibiotics
O polysaccharide antigen
Lipid A is an endotoxin
Porins (proteins) form channels through membrane
What is endotoxin?
Part of the cell structure; happens once the cell dies
What is exotoxin?
Excretes some toxin, the bacteria must be alive
What is the Gram Stain Mechanism?
Crystal violet-iodine crystals form in cell
Gram-positive - Alcohol dehydrates peptidoglycan; CV-I crystals do not leave
Gram-negative - Alcohol dissolves outer membrane and leaves holes in peptidoglycan; CV-I washes out
What is the periplasmic space?
The space between peptidoglycan and cell membrane in Gram+ (also outer membrane in G-)
What are two examples of atypical cell walls?
Mycoplasmas (cause walking pneumonia) - lack cell walls; sterols in plasma membrane
Archaea - wall-less or walls of pseudomurein (lack NAM and D amino acids)
What is Gram+ treated with lysosome and have their cell wall entirely removed?
What is Gram- treated with lysosome and have their cell wall only partially removed?
What digests disaccharide in peptidoglycan?
Where can lysosome be found?
It is in every fluid in the body.
What inhibits peptide bridges from forming in peptidoglycan?
What do all live cells have and are only differentiated by protein?
What does selective permeability mean?
Allows passage of some molecules ( H2O, gas (O2, CO2), small molecules)
What are the two types of movement across membranes?
Simple diffusion and Facilitative diffusion
What is simple diffusion?
Movement of a solute from an area of higher concentration to an area of lower concentration
What is facilitative diffusion?
Solute combines with a transporter protein in the membrane; does not need ATP; moving from higher concentration to lower concentration
What type of solution has no net movement of water?
What type of solution causes water to move into the cell and may cause the cell to burst if the wall is weak or damaged?
Hypotonic (osmotic lysis)
What type of solution causes water to move out of the cell, causing its cytoplasm to shrink?
What does active transport of substances require?
A transporter protein and ATP
What does group translocation of substances require?
A transporter protein and PEP
50s and 30s subunits makes what type of rbosome?
70s which is prokaryotic
50s and 40s subunits makes what type of ribosome?
80s which is eukaryotic
What are endospores?
Resistant to desiccation, heat, chemicals
What is sporulation?
What is germination?
Return to the vegetative state
What is phagocytosis?
Eating solids; cell eating
What is pinocytosis?
Send toxin inside cell to kill it
What do sterols make?
What is endocytosis?
Phagocytosis: Pseudopods extend and engulf particles
Pinocytosis: Membrane folds inward bringing in fluid and dissolved substance
What is cytoskeleton?
Microfilabments, intermediate filaments, microtubules
Gives shape to non-cell wall; movement
What is the sum of all chemical reactions within the cell?
What is the breakdown of complex organic molecules into simpler ones; energy is released?
What is the building of complex organic molecules from simpler ones; energy is used?
What is an enzyme?
A type of protein which catalyzes reactions in the cell by lowering the activation energy.
What is a substrate?
The compound being acted upon by the enzyme.
What is turnover number?
The maximum number of substrate molecules an enzyme can convert to product each second.
All proteins except RNAse
Specific to a substrate
Can have many turnovers (generally 1- 10,000 molecules per second)
Has an active site that is shaped to match a specific substrate
Mainly metal ions
Summarize the enzymatice action
1. Substrate binds to active site on the surface of the enzyme
2. Temporary intermediate complex forms - enzyme-substrate complex
3. Substrate transformed (other molecule added, molecule rearranged, bond broken, etc.)
4. Transformed substrate (product or products) no longer conform to the active site, is released.
5. Unchanged enzyme is ready to react with more substrate molecules
Which factors influence enzymes?
Temperature - Low, high, (optimum minimum, maximum)
pH - optimum, effects on amino acids
Substrate concentration - saturation
Which reaction is where one substrate loses electrons (oxidation) and the other gains elctrons (reduction)?
Which reaction often includes the transfer of both the electron and the accompanying proton (hydrogen atom)?
What is oxidation?
The removal of electrons
What is reduction?
The gain of electrons
What is an oxidation reaction paired with a reduction reaction?
True or False: Oxidation and reduction are always together in a reaction.
What is the removal and addition of electrons to molecules?
What is phosphorylation?
Adding a phosphate group - storing energy
What is dephosphorylation?
Removing a phosphate group - releasing energy
What is generated by the phosphorylation of ADP?
What is losing or gaining a phosphate?
What does the oxidation of glucose to pyruvic acid yield?
ATP and NADH
What is glycolysis?
The oxidation of glucose to pyruvic acid
In respiration, how many ATP are gained?
In fermentation, how many ATP are gained?
What is fermentation?
The partial oxidation of glucose in the absence of oxygen where the final electron acceptor is an organic molecule.
What is respiration?
The process by which molecules are oxidized and the final electron acceptor is an inorganic molecule.
In aerobic respiration, the final electron acceptor is
In anaerobic respiration, the final electron acceptor is
Inorganic molecule other than oxygen (or rarely, an organic molecule)
What is chemiosmosis?
The generation of ATP using a proton gradient; yield of ATP high
What is the electron transport chain?
A series of carrier molecules located in a membrane which are capable of oxidation and reduction. Energy of electrons used to establish a proton gradient
What is lipid catabolism?
The breakdown of lipids (uses enzyme CoA); some components enter the Krebs cycle
What is protein catabolism?
Some can also enter the Krebs cycle
What is carbohydrate catabolism?
Energy produced from complete oxidation of one glucose using aerobic respiration.