Exam 2 Part 2

Question 1

UV is a type of what

Answer 1

electromagnetic energy

Question 2

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

Answer 2

wavelength

Question 3

what are the three categories of ultraviolet light

Answer 3

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

Question 4

what wavelength is the most detrimental

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

Answer 4

UV C

Question 5

what is the germicidal effect related to

Answer 5

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

Question 6

what is effectiveness diminished by

Answer 6

dust

Question 7

what is ultra violet light commonly used for

Answer 7

to disinfect labs and health care environments

Question 8

why is prolonged exposure lethal

Answer 8

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

Question 9

what are the pyrimidine dimers

Answer 9

cytosine-cytosine, cytosine-thymine, thymine-thymine

Question 10

what do the pyrimidine dimers do

Answer 10

distort the DNA molecule and interfere with DNA replication and transcription

Question 11

what is light repair also known as

Answer 11

photoreactivation

Question 12

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

Answer 12

light repair

Question 13

what is the repair enzyme

Answer 13

DNA photolyase

Question 14

what is dark repair also known as

Answer 14

excision repair(involves multiple enzymes)

Question 15

what enzymes does dark repair include

Answer 15

endonuclease, helicase, DNA polymerase 1, and DNA ligase

Question 16

what does the endonuclease do

Answer 16

breaks two covalent bond in backbone

Question 17

what does helicase do

Answer 17

removes the nucleotides in the damaged segment

Question 18

what does DNA polymerase do

Answer 18

synthesizes the new strand

Question 19

what does the DNA ligase do

Answer 19

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

Question 20

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

Answer 20

decontamination

Question 21

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

Answer 21

aeroteolerance

Question 22

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

Answer 22

sterilizing the media in an autoclave

Question 23

what is found at the top

Answer 23

aerobic

Question 24

what is found at the bottom

Answer 24

anaerobic

Question 25

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

Answer 25

strict aerobes

Question 26

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

Answer 26

facultaitve anaerobes

Question 27

why are facultative anaerobes denser at top

Answer 27

due to higher ATP yield from aerobic

Question 28

these live uniformly throughout the medium

Answer 28

aerotolerant anaerobes

Question 29

survive only in environments containing lower than atmospheric levels of oxygen

Answer 29

microaerophiles

Question 30

can survive only if carbon dioxide levels are elevated

Answer 30

capnophiles

Question 31

organisms for which even small amounts of oxygen are lethal

Answer 31

strict anaerobes

Question 32

these cause an oxygen gradient

Answer 32

agar deep stabs

Question 33

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

Answer 33

tryptic soy agar

Question 34

what are agar deeps prepared with and why

Answer 34

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

Question 35

why is stab incoculated with incoculating needle

Answer 35

to introduce as little air as possible

Question 36

what does the location of growth indicate

Answer 36

the organism's aerotolerance

Question 37

when is air removed

Answer 37

when agar is autoclaved

Question 38

once the agar cools and solidifies, what occurs

Answer 38

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

Question 39

this is well adapted for cultivation of strict anaerobes and microaerophiles

Answer 39

fluid thioglycollate broth

Question 40

what are key components of FTB

Answer 40

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

Question 41

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

Answer 41

reazurin

Question 42

why is a small amount of agar added

Answer 42

to slow oxygen diffusion

Question 43

what is FTB used for

Answer 43

to illustrate microbial growth representing all levels of oxygen tolerance

Question 44

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

Answer 44

GasPak (anaerobic systems)

Question 45

what are the components required for anaerobic growth

Answer 45

chemical gas generator, paper indicator strip, and palladium

Question 46

what does palladium do

Answer 46

catalyzes a reaction between hydrogen and free O2 to create water