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Cells
Metabolism
Controlling Microbes
Viruses, etc.
Miscellaneous
100
Briefly describe how a solution with a pH of 2 differs chemically from a solution with a pH of 8.
Solutions with a pH below 7 are more acidic; while solutions with a pH over 7 are more alkaline. So the pH 2 solution is acidic, and the pH 8 solution is alkaline (or basic).
100
Enzymes serve as __________ in metabolic reactions
biological catalysts
100
What method would be preferred for controlling microbes in a dairy product AND why?
Pasteurization. This process uses just enough heat to kill potential pathogens, while not altering the taste or texture of the product.
100
Differentiate between the terms VIRION and VIROID.
A virion is the inactive form of any virus. This is what it is called when it is outside of its host (extracellular state). A viroid is a type of plant pathogen. It is simply made of small circular segments of RNA and must have an insect vector to transmit it between plants.
100
Name one virus that is known to cause cancer (and the cancer it causes).
Examples: Human papilloma virus (HPV) - cervical cancer. Epstein-Barr virus (EBV) - Hodgkin's lymphoma, Herpes 8 - Kaposi's sarcoma
200
Name two different major components of cell membranes and briefly describe their functions.
Phospholipids are the primary components of all cell membranes. Cholesterol (or ergosterol in fungal cells) is used in our cell membranes to resist the effects of temperature shifts. Protein channels, receptors, pumps, etc. may also be found on cell membranes.
200
Briefly describe how non-competitive inhibitors serve to inhibit metabolism.
Non-competitive inhibitors bind to the allosteric site of an enzyme, which causes the entire enzyme to change shape slightly. This makes the active site change shape and lose affinity for the substrate.
200
Differentiate between the terms DISINFECTION and ANTISEPSIS.
Disinfection is the reduction of microbes on inanimate objects, while antisepsis is the reduction of microbes on tissue.
200
Describe three ways animal viruses can enter/infect their host cells.
Once the virus has bound to its host cell receptors, it can enter one of three ways: Enveloped viruses can either be invited in via 'phagocytosis' or simply fuse their envelope to the host cell membrane and enter ('membrane fusion'). Naked viruses must enter through 'direct penetration', which means only the nucleic acid enters and their capsids are left behind on the membrane.
200
Why would penicillin (or other beta-lactam drug) NOT have any effect on human cells?
Beta-lactam drugs block the enzyme that builds peptidoglycan cell walls. Human cells do not have cell walls, thus the selective toxicity of this drug.
300
List the two types of glycocalyces in prokaryotes AND describe their functions.
Capsules and slime layers are both types of glycocalyces that prevent dessication. Capsules are most highly organized and serve to camoflauge the bacteria from our phagocytes. Slime layers are less organized and allow the bacteria to adhere to body surfaces.
300
Name the phase of microbial growth in which the growth rate is exponential.
Log phase
300
Briefly explain why beta-lactam drugs like penicillin will not have any effect on existing bacterial cells.
Beta-lactam drugs can only interfere with the cross-linking enzymes during the cell wall synthesis stage. It cannot punch holes in existing cell walls.
300
List the 5 major stages of lytic replication in a phage:
1) Attachment (requires affinity between host & phage). 2) Entry (nucleic acid enters host cell). 3) Synthesis (viral proteins and nucleic acids are synthesized). 4) Assembly (new virions are assembled). 5) Release (new virions lyse host cell and find new host cells to infect).
300
Chains of spherical cells would have what morphology & arrangement?
Morphology = cocci. Arrangement = streptococci.
400
Describe the 'anatomy' of a Gram negative (-) bacteria. (What layers of protection do they have & what are they made of?)
Gram negative bacterial cells have a typical cell membrane made of phospholipids, then a thin layer of peptidoglycan makes up their cell wall (superficial to c.m.), plus an outer membrane made of phospholipids and lipopolysaccharide (LPS), also referred to as endotoxin or lipid A. The outer membrane can be problematic in the human body when the bacteria dies, because it these substances are released and can trigger shock.
400
Briefly explain why lipids provide more 'energy' to a cell than carbohydrates do.
While glucose is metabolized quickly, it can only produce ~36 ATP through one round of cellular respiration. Lipids (triglycerides) will take longer to metabolize, first via lipase enzymes that release a glycerol molecule that can enter glycolysis. Then beta oxidation which will release 2-carbon sections from the long fatty acid chains and EACH one can enter Kreb's cycle as if it were one glucose, thus producing much more ATP.
400
What is the ultimate consequence of antibiotic resistance to our society as a whole?
There will no longer be effective medications available to treat infections. Patients will have to rely on their immune systems to protect them.
400
Briefly explain what an 'oncovirus' is and how it operates.
Oncoviruses are viruses that promote cancer. Cell growth is controlled by oncogenes (stimulate cell growth) and repressor genes (stop cell growth). Viruses that can insert into host DNA may interfere with one or both of these and cause cancer.
400
Bacteria with multiple flagella coming off at one end would be described as _____; while those with one flagella at each end would be called ______.
Lophotrichous. The prefix lopho- means 'tuft'. Amphitrichous. The prefix amphi- means 'both'.
500
Name two substances found in prokaryotic cell walls.
Bacterial cell walls are made of peptidoglycan. This contains both NAG/NAM (sugar 'bricks') and tetrapeptide cross-bridges ('mortar' made of 4 amino acids that serve to cross-link the NAG/NAM subunits).
500
Where specifically does ATP production in prokaryotes occur? (Which membrane is responsible for the ETC?)
The cell membrane. It is the only one they have. Eukaryotic cells are more complex and the electron transport chain occurs on the inner mitochondrial membrane.
500
Briefly describe the purpose of the 'Preservation of Antibiotics for Medical Treatment Act'.
This legislation is designed to restrict antibiotic use in the livestock and agriculture industries to treat diseased animals only. Currently the bulk of antibiotics use is simply as growth enhancers or prophylactics. It would also restrict which antibiotics could be used for animals and would be different from those reserved for human use only.
500
Define TSE, briefly describe how these diseases are transmitted, how they manifest in the infected individual, and one example disease and the species it affect.
TSE's are transmissible spongiform encephalopathies (prion diseases). Prions are primarily transmitted via ingestion. Prions cause normal proteins in the membranes of neurons to refold into the disease form which kills the cell and leaves the brain full of holes. Example: chronic wasting disease (CWD) in deer & elk.
500
Name one advantage, one disadvantage, and one example of each of the following methods of control. 1) ALCOHOL 2) PHENOLS
1) Alcohol evaporates quickly, which is both advantageous and not. It does not leave a residue, which is good; but it might be gone before it can kill anything present (Ex: hand sanitizer). 2) Pinesol is a phenol that is effective even in the presence of organic matter (like blood), but has a strong odor.