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Microbiology Lab > Exam 2 Part 2 > Flashcards

Exam 2 Part 2 Flashcards

1
Q

UV is a type of what

A

electromagnetic energy

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2
Q

this is the distance between adjacent wave crests, measured in nm

A

wavelength

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3
Q

what are the three categories of ultraviolet light

A

UV A (315-400 nm), UV B (280-315 nm), UV C (100-280 nm)

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4
Q

what wavelength is the most detrimental

exposure to this for more than a few min usually results in damage or death

A

UV C

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5
Q

what is the germicidal effect related to

A

time of exposure, lamp intensity, and distance to the target

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6
Q

what is effectiveness diminished by

A

dust

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7
Q

what is ultra violet light commonly used for

A

to disinfect labs and health care environments

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8
Q

why is prolonged exposure lethal

A

DNA absorbs UV radiation at 254 nm the energy is used to form new covalent bond between adjacent pyrimidines

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9
Q

what are the pyrimidine dimers

A

cytosine-cytosine, cytosine-thymine, thymine-thymine

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10
Q

what do the pyrimidine dimers do

A

distort the DNA molecule and interfere with DNA replication and transcription

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11
Q

what is light repair also known as

A

photoreactivation

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12
Q

when is the repair enzyme activated by visible light and reverses the original reaction

A

light repair

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13
Q

what is the repair enzyme

A

DNA photolyase

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14
Q

what is dark repair also known as

A

excision repair(involves multiple enzymes)

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15
Q

what enzymes does dark repair include

A

endonuclease, helicase, DNA polymerase 1, and DNA ligase

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16
Q

what does the endonuclease do

A

breaks two covalent bond in backbone

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17
Q

what does helicase do

A

removes the nucleotides in the damaged segment

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18
Q

what does DNA polymerase do

A

synthesizes the new strand

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19
Q

what does the DNA ligase do

A

forms a covalent bond between the new and original strands (closes gap)

20
Q

what can ultraviolet radiation be used in due to lethal effects on bacterial cellls

A

decontamination

21
Q

this is the ability of inability to live in the presence of ozygen

A

aeroteolerance

22
Q

this kills unwanted microbes and removes most of the free oxygen from the media as well

A

sterilizing the media in an autoclave

23
Q

what is found at the top

A

aerobic

24
Q

what is found at the bottom

A

anaerobic

25
Q

these are organisms that require oxygen for aerobic respiration
grow at the top where O2 is plentiful

A

strict aerobes

26
Q

grow in the presence or absence of oxygen
can respire BOTH aerobically and anaerobically
grow throughout the medium but dense at top

A

facultaitve anaerobes

27
Q

why are facultative anaerobes denser at top

A

due to higher ATP yield from aerobic

28
Q

these live uniformly throughout the medium

A

aerotolerant anaerobes

29
Q

survive only in environments containing lower than atmospheric levels of oxygen

A

microaerophiles

30
Q

can survive only if carbon dioxide levels are elevated

A

capnophiles

31
Q

organisms for which even small amounts of oxygen are lethal

A

strict anaerobes

32
Q

these cause an oxygen gradient

A

agar deep stabs

33
Q

this is enriched with yeast extract to promote growth of a broad range of organisms

A

tryptic soy agar

34
Q

what are agar deeps prepared with and why

A

10 mL of medium, the extra depth ensure bottom portion of medium is anaerobic

35
Q

why is stab incoculated with incoculating needle

A

to introduce as little air as possible

36
Q

what does the location of growth indicate

A

the organism’s aerotolerance

37
Q

when is air removed

A

when agar is autoclaved

38
Q

once the agar cools and solidifies, what occurs

A

air diffuses back into the agar and a concentration gradient is formed

39
Q

this is well adapted for cultivation of strict anaerobes and microaerophiles

A

fluid thioglycollate broth

40
Q

what are key components of FTB

A

yeast extract, pancreatic digest of casein, dextrose, sodium thioglycollate, L-cytosine, and reazurin

41
Q

this is an indicator of O2(pink) when presnet and colorelss when reduced

A

reazurin

42
Q

why is a small amount of agar added

A

to slow oxygen diffusion

43
Q

what is FTB used for

A

to illustrate microbial growth representing all levels of oxygen tolerance

44
Q

this is a plastic jar in which to create anaerobic, microaerophilic, or CO2 enriched conditions

A

GasPak (anaerobic systems)

45
Q

what are the components required for anaerobic growth

A

chemical gas generator, paper indicator strip, and palladium

46
Q

what does palladium do

A

catalyzes a reaction between hydrogen and free O2 to create water

Microbiology Lab (25 decks)

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