Bacteria
What do amphitrichous and peritrichous mean?
Amphitrichous: having a flagellum on each opposite end of a bacterial cell.
Peritrichous: having flagella all around the bacterial cell.
Name two structures that are unique to prokaryotes.
Fimbria/pili and endospores
Nucleoid is maybe acceptable...
What is the final electron acceptor of anaerobic respiration?
An external inorganic or organic molecule, NOT oxygen. Examples include NO3, SO4, CO3.
What is aseptic technique? What are some actions that can be performed to achieve this?
It is a series of steps taken to prevent contamination of laboratory culture and media while working with it.
Examples include passing an inoculation loop through a Bunsen burner to clean it while transferring specimen, disinfecting the lab bench before working on it, washing ones hands before and after working with a specimen, limiting the amount of time that specimen are exposed to open air, etc.
What is a mutation? What is a mutagen?
A mutation is a heritable change in the base sequence of that genome. It can lead to changes, but not always.
A mutagen is an agent that causes a mutation. Examples include radiation, intercalating agents, and alkylating agents.
Describe the cell wall of mycobacteria.
Resembles a gram-positive cell wall. They do not stain well because they have a very waxy and hydrophobic surface. They contain a type of lipid called mycolic acid (bacteria-specific).
How is the composition and motion of prokaryotic vs eukaryotic flagella different?
Prokaryotic: simpler, made of flagellin, and moves in a propeller-like (rotary) motion
Eukaryotic: more complex (9+2 arrangement of microtubules), made of tubulin, and moves in a whip-like motion
During periods of nutrient abundance, how can cells prepare for periods of nutrient starvation?
Nutrients can be stored as insoluble polymers that can later be catabolized. This is what inclusion bodies are. Examples of stored nutrients include glycogen, poly-B-hydroxybutyrate, and elemental sulfur (H2S).
In an endospore stain, what color should the positive and negative results be? Which dyes are used in this type of staining?
Positive: red/pink. Dye=Safranin.
Negative: green. Dye=Malachite green.
Name the three types of horizontal gene transfer
Transformation, transduction, and conjugation
Name and describe the two types of glycocalyces for bacteria.
Capsule: Firmly attached and tightly organized to the bacterium
Slime layer: Loosely attached and easily deformed
What is peptidoglycan? What is it made of?
Peptidoglycan is a rigid polysaccharide that forms the cell walls of bacteria. It is made up of alternating repeats of two modified glucose residues: N-acetylmuramic acid and N-acetylglucosamine. It also contains both L and D amino acids.
What does NAD stand for, why kind of molecule is it, and why is it needed in metabolism?
Nicotinamide adenine dinucleotide. It is a nucleic acid. It is a high energy electron and proton carrier that helps with redox reactions.
Name Koch's postulates.
1) The suspected pathogen must be present in all cases of the disease and absent from healthy animals.
2) The suspected pathogen must be grown in a pure culture.
3) Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal.
4) The suspected pathogen must be reisolated and show to be the same as the original.
How is a proton motor force (pmf) normally established and how can it be established if an organism lacks an ETC?
In aerobic or anaerobic respiration, the ETC is used in conjunction with the ATPase in order to establish this proton gradient. If an organism does not have an ETC, the ATPase is run in reverse to hydrolyze ATP and establish this gradient.
What is an endotoxin and what kind of bacteria are they associated with?
Endotoxins are toxic substances that are present within of the outer membrane of the gram-negative bacterial cell. When the outer membrane begins to break down, these toxins are released into the surrounding environment.
Lipid A within the LPS of the outer membrane is the endotoxin.
Draw a general bacterial cell and label these structures: cell membrane, cytoplasm, cell wall, ribosomes, chromosome, nucleoid, flagella, pili, glycocalyx, plasmid, and inclusion.
*Look up diagram*
How much ATP is made in the following: aerobic respiration, anaerobic respiration, and fermentation.
~38, 2-36, and 2 (respectively).
What are the steps of the gram stain procedure?
1) Prepare a heat fixed slide with the bacterial culture
2) Flood the slide with crystal violet dye. This will stain all cells purple.
3) Apply iodine to the slide as a mordant
4) Use an alcohol as a decolorizer to remove the purple dye from the gram negative bacteria
5) Apply safranin to the slide to color the gram negative bacteria.
What is the endosymbiotic hypothesis? Name at least two pieces of evidence that support it.
A hypothesis which states that mitochondria and chloroplasts are descendants of respiratory and phototrophic bacterial cells which then associated with a non phototrophic eukaryotic host which benefited from having these structures (more efficiency in metabolism).
Evidence:
1) Mitochondria and chloroplasts contain their own genomes that are separate from the cell's original DNA.
2) Their genomes are arranged in a circular fashion instead of linear
3) They contain 70S ribosomes instead of 80S.
4) The eukaryotic nucleus contains genes derived from bacteria.
Draw a gram positive and gram negative cell with labels. Must include peptidoglycan, a lipopolysaccharide layer, teichoic acids, cell membrane, periplasmic space, and the outer membrane.
*look up diagram online*
Gram positive should have thick peptidoglycan cell wall with teichoic acid embedded within it, a periplasmic space, and a cell membrane.
Gram negative should have an outer membrane that has LPSs embedded within it, a thin peptidoglycan wall contained within a periplasmic space, and a cell membrane.
Compare the analogous structures of the cytoskeleton of a eukaryote to a prokaryote.
Eukaryote : Prokaryote
Tubulin = FtsZ
Actin = MreB
Intermediate filaments= CreS
Name the six types of fermentation, give an example of the products they help to create.
BONUS 50 points if you can list an example of an organism that utilizes each fermentation type (50 points per organism).
1) Propionic acid. Makes holes in swiss cheese. Ex: Propionibacterium
2) Lactic acid. Makes cheddar cheese, yogurt, and soy sauce. Ex: Aspergillus, Lactobacillus, and Streptococcus
3) Alcoholic. Makes wine and beer. Ex: Saccharomyces
4) Acetone, butanol. Makes nail polish remover and rubbing alcohol. Ex: Clostridium.
5) Mixed acid (acetic/formic/lactic acid). Used in and MR test to ID bacteria based on pH change. Ex: Escherichia, Shigella
6) 2,3-butanediol fermentation. Used in VP test (looks for presence of acetoin which helps to identify the specific metabolic pathway that that organism uses in fermentation). Ex: Enterobacter
In a dilution series, 1mL of the original solution was combined with 9mL of saline in tube A. 0.1mL of tube A was transferred to tube B which contained 0.9mL of saline. Lastly, 0.1mL of tube B was transferred to tube C which contained 9.9mL of saline. 0.1mL of each tube was plated and incubated. On plate A, 2,530 colonies were formed. On plate B, 250 colonies formed. On plate C, 3 colonies formed.
What is the cell density of the original solution?
2.5x10^5 CFU/mL
C=(250 colonies (10^2))/(1x10^-1)mL
What are the three toxic oxygen products produced during respiration? Which enzymes are used to detoxify the cell from these products?
Toxic oxygen products
1) Superoxide anion (O2-)
2) Hydrogen peroxide (H2O2)
3) Hydroxyl radical (OH-)
Enzymes
1) Superoxide dismutase
2) Catalase
3) Peroxidase