Micro. Phase 2 Flashcards
For which experiment in the field of virology is Wendell Stanley known?
the crystallization of the tobacco mosaic virus
What is a T-even phage?
The T-phages are a group of 7 bacteriophages that infect e-Coli.
The T-even phages are the even numbered ones: T2,T4 etc.
Which wavelength from within the electromagnetic spectrum contains ultraviolet rays that are used in lamps to sterilize surfaces?
260 μm
UV spectrum = 100-400
What is the mechanism of action of vancomycin?
What other antibiotic has the same MOA?
Inhibits cell wall synthesis.
Cephalothin
What is the MOA of erythromycin and neomycin?
Inhibits protein synthesis
What is the MOA of sulfonamides?
Inhibits protein synthesis.
What is the MOA of chloramphenicol?
Inhibits protein synthesis.
What is another name for protein synthesis?
Translation
At what temp are vegetative bacteria cells killed?
At what temp are viable bacterial endospores killed?
Vegetative: 70C
Endospores: 100C
Which substances kill microorganisms by replacing the hydrogen of the carboxyl, sulfhydryl, or amino groups?
aldehydes
Aldehydes form covalent bonds with protein functional groups.
Which agent inhibits the replication of bacterial DNA by inducing the formation of thymine dimers?
UV light
Ultraviolet nonionizing radiation damages DNA by forming thymine dimer when adjacent thymine bases form bonds together.
When treating a wound, which compound would be most effective to prevent infection? a. 30% alcohol
- chlorine
- Tincture of iodine
- Formaldehyde
Tincture of iodine
Iodine tincture is one of the most effective antiseptics against all bacteria, many endospores, and many viruses.
What is the causative agent of gum lesions caused by bacterial periodontal disease?
Porphyromonas
An individual with food intoxication exhibits double vision, difficulty in swallowing, dizziness, and muscle paralysis. Which organism caused this condition?
Clostridium
What type of bacteria causes Toxic Shock Syndrome?
Toxic shock syndrome results from staphylococcal infection.
In microscopy, which is an advantage of using violet-blue light (420 nm) rather than red light (680 nm)?
Violet light improves resolution. - the shorter the wave length, the better the resolution.
Which strains of Corynebacterium diphtheriae synthesize diphtheria toxin?
strains lysogenic for corynephage
The diphtheria toxin is produced when the bacteria are infected by lysogenic phage carrying the tox gene.
What is the infectious agent of CSD (cat scratch disease)?
Bartonella henselae
What is the MOA of rifamycin?
Inhibits bacterial RNA synthesis.
During the polymerase chain reaction (PCR) process, the incubation mixture is made to cycle between low and high temperatures many times. What is the purpose of the high temperature?
to denature template DNA
Heating converts the double-stranded DNA to single-stranded DNA. Cooling allows the primers to attach to the single strands.
Which ingredient makes mannitol salt agar a selective medium?
Sodium Chloride
Sodium chloride is a salt that inhibits non-Staph. aureus growth.
Folic acid functions as a coenzyme for which process?
Synthesis of purines
How do temperatures above the maximum growth temperature for a bacterial species generally inhibit growth?
by denaturing enzymes
Excessive heat denatures protein. Enzymes are proteins.
When a competitive inhibitor binds to a particular enzyme, how can the reaction rate be increased?
by increasing substrate concentration
Increasing substrate concentration increases the reaction rate, because the enzyme has more noninhibited substrate active sites to react with
Which organic compound is found only in cell walls of bacteria? 1. Cellulose
- Chitin
- N-acetylmuramic acid
- Phospholipids
N-acetylmuramic acid
How do the lytic cycle and the lysogenic cycle of bacteriophages differ?
In the lytic cycle, phage virions are released when the cell lyses. In the lysogenic cycle, the phage DNA is incorporated into the host DNA as prophage.
For a suspension of 1000 infectious phage particles per mL, it is known that at each cycle of invasion, 80% of the particles for this strain of phage will be lytic and 20% will be lysogenic. If 0.1 mL of virus suspension is plated onto a susceptible host, what would the expected plaque-forming units (pfu) count be after a 24-hour incubation?
80 pfu, because 20% of the first invasion cycle will not form plaques
If there are 1000 particles per mL, then 0.1 mL = 100 particles. If 80% of these particles are lytic, then 80 plaques will form. Lytic phages result from phage destroying the host bacteria in the culture medium.
The last step of gram staining is with safranin. What color will gram negative bacteria appear?
Red or pink
Plasmids most often encode for enzymes involved in ___________?
antibiotic resistance
What is denitrification?
Denitrification converts nitrates to nitrogen gas, depriving crops of nitrogen.
What is ammonification?
Ammonification enables plant and bacterial amino acid synthesis.
What is nitrogen fixation?
Nitrogen fixation converts nitrogen gas to ammonia to start the nitrogen cycle.
describe oil-degrading bacteria, such as those used to clean up oil spills?
heterotrophs that oxidize the oil as a source of carbon and energy
Give an example of a bacterially synthesized secondary metabolite?
Penicillin
In which environment is denitrification most likely to occur?
In areas of low oxygen levels such as fertilized, waterlogged garden soil
What increases the rate of bioremediation of an oil spill?
Bioremediation in oil spills is enhanced by providing oxygen, nitrogen, and phosphate to the bioremediation microbes.
What does “atopic” mean?
Give an example of an atopic immune disease.
Atopic = chronic & local
Example: hay fever, asthma, eczema
What is the prodromal period of a disease?
Prodromal is the period after incubation when, in some diseases, mild symptoms become manifest.
How are diseases such as AIDS, tuberculosis, and malaria characterized?
infectious, opportunistic, epidemic
What is the Wasserman complement fixation test
Used to test for syphillis
Which criterion indicates a concern for hemolytic disease in a newborn?
the father and fetus are Rh+ and the mother is Rh-
If the fetal Rh positive blood enters the Rh negative maternal circulation, the mother will mount an immune response against the foreign Rh positive antigens of the fetal blood.
Which antibody isotype containing a secretory component can be transported across membranes?
IgA
IgA contains a secretory component bound to the monomers by a J chain, and can cross membranes
A gram-positive bacterium is exposed to the enzyme lysozyme. What will be the result of this exposure?
The lysozyme will degrade the mucopeptide layer of the cell wall, causing the cell to lyse.
What do persons with type O blood have?
both anti-A and anti-B antibodies circulating in their plasma
Type O blood lacks A antigens and B antigens. Thus it has anti-A and anti-B antibodies.
Euglena is classified as having which nutrition process?
Photoautotrophic
