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Microbiology > Chapter 9-10 Pearson > Flashcards

Chapter 9-10 Pearson Flashcards

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Biology 101 flashcards
1
Q

Of the microbes classified as aerotolerant anaerobes, facultative anaerobes, microaerophiles, obligate aerobes, and obligate anaerobes, which would be harmed by a high oxygen concentration in their environment?

A

Microaerophiles and obligate anaerobes

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2
Q

Consider a mesophilic bacterium. What would happen if this bacterium were exposed to a temperature much higher or lower than its optimal temperature?

A

It would stop growing and possibly be killed.

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3
Q

Some microbes are halophiles and can withstand a high salt concentration in their environment. What happens to nonhalophiles under such a condition?

A

Water leaves the cell.

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4
Q

Why do endospores form?

A

Endospores form as a defense strategy against inhospitable conditions.

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5
Q

Which halogen is commonly used to degerm surgical sites?

A

Iodine

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6
Q

When might a researcher more likely use filtration as a sterilization method?

A

When she is working with heat-sensitive materials.

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7
Q

Hydrogen peroxide does NOT make a good antiseptic for open wounds because __________.

A

Catalase in human tissues neutralizes it

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8
Q

Which heat-related method of microbial control most effectively destroys bacterial endospores?

A

Autoclaving

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9
Q

What could be used to sterilize a heat-sensitive liquid such as urea broth?

A

filtration

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10
Q

Which techniques can be used to sterilize microbiological media?

A

autoclaving

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11
Q

Milk that can be stored for months at room temperature has been treated by which of the following methods?

A

ultrahigh-temperature sterilization

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12
Q

Compared to moist heat methods, dry heat needs which of the following in order to sterilize effectively?

A

higher temperature and increased time

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13
Q

Damage to the cell wall will adversely affect a bacterial cell by making it more susceptible to __________.

A

osmotic pressure

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14
Q

An antimicrobial chemical used on the skin is usually called __________.

A

an antiseptic

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15
Q

Which of the following is NOT associated with the work of Paul Ehrlich?

A

sulfanilamide

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16
Q

The microbial growth curve has four phases: lag, log, stationary, and death. If a chemical could prevent microbial cell division, in which phase of growth would it be most effective?

A

The log phase

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17
Q

Considering the cell structure of mycoplasmas and other bacteria that stain either Gram negative, Gram positive, or with acid-fast stains, which group should you expect relies most on the presence of peptidoglycan for strength?

A

Gram-positive bacteria

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18
Q

What is the function of tRNA during the process of translation?

A

tRNA brings amino acids to a growing chain of amino acids in ribosomes.

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19
Q

What is the difference between prokaryotic and eukaryotic ribosomes?

A

Prokaryotic ribosomes consist of a 50S large and a 30S small subunit, while eukaryotic ribosomes consist of a 60S large and a 40S small subunit.

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20
Q

What is microbial antagonism?

A

the ability of the normal flora to outcompete and outgrow pathogens

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21
Q

What is a superinfection?

A

Superinfection is a disease caused by an organism that is often an opportunist or one that was present in low numbers. Superinfection is a sequel to removal of the normal flora by antibiotic treatment.

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22
Q

What causes thrush?

A

Candida albicans

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23
Q

Which of the following classifications would best describe Candida albicans?

A

yeast

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24
Q

If the patient were to get a subsequent urinary tract infection, what should the doctor prescribe, knowing that she is susceptible to thrush?

A

The doctor should prescribe an antibiotic specific for the bacterial species causing the urinary infection.

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25
Q

Which group of drugs includes nystatin and amphotericin B and cause cell lysis by forming channels in the cytoplasmic membranes of fungal cells?

A

Polyenes

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26
Q

Sulfonamide drugs inhibit microbial growth by disrupting metabolic pathways. What general mechanism do these drugs use?

A

Competitive inhibition

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27
Q

What is the general term used to describe drugs that are chemically similar enough to a metabolite (such as PABA or a nucleotide) that they can substitute for that metabolite in a chemical reaction, possibly disrupting the chemical reaction sufficiently to halt the process?

A

Analog

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28
Q

How do the antiviral drugs amantadine and rimantadine work?

A

They prevent viral uncoating by increasing the pH in phagolysosomes.

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29
Q

A class of antiviral drugs known as attachment antagonists help deter viral infections. What mechanism do they use?

A

They prevent attachment.

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30
Q

A class of antiviral drugs known as attachment antagonists help deter viral infections. What mechanism do they use?

A

They prevent attachment.

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31
Q

What is meant by selective toxicity?

A

Chemotherapeutic agents should act against the pathogen and not the host.

32
Q

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?

A

Humans and other animal hosts lack peptidoglycan cell walls.

33
Q

Why is polymyxin only used on the skin?

A

It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

34
Q

Quinolones and fluoroquinolones act against what bacterial target?

A

DNA gyrase

35
Q

Why is it difficult to find good chemotherapeutic agents against viruses?

A

Viruses depend on the host cell’s machinery, so it is hard to find a viral target that would leave the host cell unaffected.

36
Q

If a particular bacterial species is resistant to beta-lactam antibiotics, which of the following might you expect to find inside the bacterial cells?

A

R plasmids

37
Q

Which of the following is NOT associated with microbial mechanisms of resistance?

A

denaturation of proteins

38
Q

A patient has been diagnosed with a disease caused by a drug-resistant strain of bacteria. What is a likely way that the bacterium initially acquired resistance?

A

Mutation

39
Q

A patient is infected with a bacterium that produces the enzyme beta-lactamase; this enzyme.

A

Inactivates penicillins, carbapenems, and cephalosporins.

40
Q

Which of the following does not spread drug resistance throughout a population of bacteria?

A

Efflux pumps

41
Q

A particular drug works by interfering with cellular metabolism in Gram-negative bacteria. How might these bacteria become resistant in a way that Gram-positive bacteria never could?

A

Alter prorin proteins in the cell’s outer membrane.

42
Q

By what mechanism do bacteria develop resistance to tetracycline?

A

The bacteria prevent the entry of tetracycline into the cells.

43
Q

When a nurse rubs your skin with rubbing alcohol prior to administering an injection, what process(es) is he carrying out?

A

Antisepsis, Degerming

44
Q

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?

A

Whether or not hand sanitizer is available at the changing table

45
Q

Many MRSA strains are sensitive to other antibiotics. Which of the following methods would be the best way to evaluate sensitivity to other antibiotics?

A

Disk diffusion

46
Q

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

A

Production of a beta-lactamase

47
Q

Clostridium difficile is a common healthcare associated infection. It is a Gram-positive spore-forming anaerobe that is associated with antibiotic therapy. It is most commonly transferred between patients on the hands of health care workers. Based on this information, rank the following prevention and control strategies from most beneficial (1) to least beneficial (4).

A

Most
Hand hygiene with soap and water.
use of gloves.
use of approved chemical disinfectants in the patient’s room.
hand hygiene with alcohol gel.

48
Q

What is meant when a bacterium is said to become “resistant” to an antibiotic?

A

The bacterium is neither killed nor inhibited by the antibiotic.

49
Q

When a patient is treated with antibiotics, __________.

A

The drug will kill or inhibit the growth of all of the sensitive bacterial cells.

50
Q

The process of acquiring antibiotic resistance by means of bacteriophage activity is called.

A

Transduction.

51
Q

Which of the following mutations would not result in antibiotic resistance?

A

Silent mutation

52
Q

R-plasmids are most likely acquired via

A

Bacterial conjugation.

53
Q

The physical removal of microbes is called.

A

degerming

54
Q

An instrument that will come into contact with only the skin of a patient should be disinfected with a(n)

A

Low-level germicide.

55
Q

Antimicrobial agents usually work best at high temperatures and high pH levels. T/F

A

False

56
Q

Which of the following is bacteriostatic?

A

freezing below 0°C

57
Q

Which of the following is NOT a feature associated with filtration?

A

Varying thicknesses of membrane filters used

58
Q

The process of filtration can be a(n)

A

sterilizing method

59
Q

Ultraviolet light penetrates (more/less) effectively than gamma rays.

A

less

60
Q

Silvadene, a topical treatment for burns, contains 1% silver. What category of chemical control agent is in Silvadene?

A

heavy metals

61
Q

Which of the following is a sterilizing agent?

A

peracetic acid and hydrogen peroxide

62
Q

Alcohols are used for

A

Both antisepsis and disinfection.

63
Q

Beta-lactam antibiotics such as penicillins, have an effect on which of the following types of cells?

A

bacterial cells

64
Q

Which of the following drugs specifically targets cell walls that contain mycolic acid?

A

isoniazid

65
Q

Which of the following is NOT a target of drugs that inhibit protein synthesis?

A

interference with alanine-alanine bridges

66
Q

A drug is structurally similar to PABA and inhibits folic acid synthesis. It is most likely a(n)

A

Sulfonamide.

67
Q

Which of the following statements is TRUE of selective toxicity?

A

Selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen.

68
Q

Antimicrobials known as “attachment antagonists” are particularly useful for preventing.

A

Virus infection.

69
Q

Nucleotide or nucleoside (acids/analogs/antisense) are antimicrobial agents that mimic the chemical structure of DNA building blocks.

A

analogs

70
Q

Drugs known as beta-lactams interfere with bacterial (DNA/folic acid/cell wall) synthesis.

A

cell wall

71
Q

Medications that block viral entry into cells include (adhesin/analog/attachment) antagonists.

A

attachment

72
Q

Antisense nucleic acids interfere with protein synthesis.

A

True

73
Q

The outer membrane of Gram-negative bacteria enables many antimicrobial drugs to enter the cell more easily.

A

False

74
Q

Some bacterial cells are resistant to a variety of antimicrobials because they actively pump the drugs out of the cell.

A

True

75
Q

How does resistance to drugs spread in bacterial populations?

A

Horizontal gene transfer between bacteria spreads R (resistance) plasmids.

76
Q

Some bacteria are resistant to antimicrobials due to the activity of ________, which removes many of them.

A

efflux pumps

Microbiology (23 decks)

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