CHAPTER 10 Exam 2

prokaryotes contain ____ ribosomes

70s. composed of smaller 50s and 30s subunits

antimicrobial drugs are selectively toxic this means

the drugs are more toxic to the pathogens than to the patient

the tRNA molecule holding a growing polypeptide chain is at the

P site, they hold the developing polypeptide chains

which category of antimicrobial drug works by changing the shape of a ribosome

aminoglycosides. they change the shape of a 30s subunit causing the ribosome to misread the mRNA

which category of an antimicrobial drug essentially acts to start a ribosome as it reads mRNA

macrolides. they block the movement of a ribosome along mRNA, so the E site is never emptied and polypeptide formation is stopped

chlramphenicol blocks the action of the large (50s) subunit. this essentially ___

prevents the formation of peptide bonds. without the formation of peptide bonds, amino acids diffuse away and protein synthesis ceases

which antimicrobial drugs affect the structure of the ribosome itself

aminoglycosides

antisense nucleic acids

oxazolidinones

each of these drugs actually modifies, or prevent the formation of the complete 70S ribosome

which category of drug is complementary to mRNA of the pathogen

antisense nucleic acids.

these are composed of the same nucleotide bases, and are complementary to the mRNA

rank the following point mutations in order of least damaging to most damaging if they occur in the middle of the coding sequence of a polypeptide

silent, missense, frameshift, nonsense

not all changes in amino acid sequences are deleterious some even be beneficial. which of the following point mutations is most likely to alter a protein product without destroying its function ?

missense; changes in gene sequences that alter function without destroying the function of a polypeptide may become permanent in the genome of the organism

which of the following will most likely contribute to the spread of a genetic mutation among bacterial species

transformation

which of the following statements is MOST correct, regarding the development of antibiotic resistance in populations of bacteria

exposure to antibiotics selects for the members of a bacterial population, which already have a resistant phenotype.

frameshift

extensive change in gene product structure and function

nonsense

premature termination of gene product with probable loss of function

silent

no change in gene product

missense

small change in gene product which may or may not alter function

rank the following events in order from greatest to least contribution to the spread of antibiotic resistance in bacterial populations

horizontal, vertical, new mutations

when a nurse rub your skin with rubbing alcohol prior to administering an injection which process is he carrying out?

antisepsis

degerming

which of the following is not an important consideration, when preparing to use a chemical to disinfect a diaper changing table in a public restroom

whether or not hand sanitizer is available at the changing table

many MRSA strains are sensitive to other antibiotics. which of the following methods would be the best way to evaluate sensitivity to other antibiotics

disk diffusion ; the key point and identifying treatment options for MRSA is to identify which non-beta-lactam antibiotics it is sensitive to

examining a muscle strain, researchers find that degraded penicillin is found in the culture medium. What is the most likely mechanism of resistance?

production of beta-lactamase ; different MRSA strains can produce beta lactamases, efflux pumps & unexpressed altered PBP‘s to which, beta lactam’s cannot bind

rank the following prevention and control strategies from most beneficial to least beneficial

hand hygiene with soap and water

use of gloves

use of approval chemical disinfectants in patient rooms

hand hygiene with alcohol gels

(against the spread of clastridium difficile)

based on the data shown, what are the possible resistant mechanisms of this patient resistant strains of K pneumoniae

decreased permeability, altered, drug target, efflux pumps, drug inactivation

The first true antibiotic was ___ __*, which was discovered by*__ _____

penicillin; alexander fleming

Who discovered the first antimicrobial widely available to the general public

Domagk

An antimicrobial that inhibits bacterial cell wall synthesis will result in which of the following

bacterial cells become more susceptible to osmotic pressure

beta-lactam antibiotics, such as penicillin’s have an effect on which of the following types of cells

bacterial cells

most drugs that inhibit the synthesis of the cell wall act by

preventing the cross linkage of NAM sub units

antimicrobial is known as “attachment antagonists” are particularly useful for preventing

virus infection

the anti microbial polymyxin

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disrupts cytoplasmic membranes

drugs, known as beta-lactams interfere with bacterial

cell wall synthesis

and antimicrobial disk on a Kirby Bauer plate that shows no zone of inhibition indicates that the micro being tested is ____ to the drug

resistant ; a zone of inhibition measures the effectiveness of a drug. a drug disk with no zone of inhibition would clearly indicate microbe resistant to that drug

which of the following groups of drugs can become incorporated into the bones and teeth of a fetus?

tetracyclines

most broad-spectrum antibiotics act by

inhibiting protein synthesis

The broth dilution test can provide information for determining

both the MIC and the MBC (additional step)

a ______ concentration of a drug is one at which microbes survive but aren’t able to grow and reproduce

bacteriostatic

which of the following activities can be shown to increase resistance among microbial populations

taking antibacterial drugs for viral infections

it is inappropriate to prescribe antibacterial agents to treat cold or flu, because

these diseases are caused by viruses

some bacterial cells are resistant to a variety of antimicrobial’s, because they actively pump the drug out of the cell

true