Control of microorganisms

Question 1

what is the D value

Answer 1

The value that reduces the the population by 1 log (90%)

Question 2

what is an autoclave

Answer 2

An autoclave kills bacteria by protein denaturation
-prions cannot be destroyed unless you use an oxidizing agent

Question 3

three major ways of killing bacteria

Answer 3

1. by damaging the plasma membrane
2. denature proteins
3. strong oxidizing agent

Question 4

what temperature and pressure allows you to destroy all endospores

Answer 4

15 psi and 121 C

Question 5

what is pasteurization

Answer 5

designed to protect public health and destroy heat resistant and vegetative cells ex: (Q fever) *not endospores we dont know about viruses tho

Question 6

what does shelf life reflect

Answer 6

the number of microorganisms left in the dairy product

Question 7

50% of flies harbor what kind of bacteria

Answer 7

E. coli

Question 8

what kind of organism gets past the filter sterilization

Answer 8

viruses (only bacterial free

Question 9

what kind of radiation is bactericidal

Answer 9

gamma rays

Question 10

what kind of light can kill microorganism

Answer 10

UV light (with close contact) by causing the cell to form lethal thymine dimers

Question 11

auto calving has a hard time killing what kind of gram bacteria?

Answer 11

lipopolysaccaride (will survive autoclaving)
gram negative

Question 12

is moist heat or dry heat more effective

Answer 12

moist heat because of hydrogen bonding

Question 13

what is lypophilization

Answer 13

does not kill bacteria
- decreased chemical reactions and possible changes in proteins

Question 14

what does deep freezing do to bacteria

Answer 14

kills 90% of bacteria

Question 15

how does desicccation work

Answer 15

by disrupting metabolism

Question 16

how does ionization kill bacteria

Answer 16

destruction of DNA (used to sterilize pharmaceuticals and medical and dental supplies

Question 17

what was the first disinfectant used

Answer 17

phenol

Question 18

what is a phenol coefficient

Answer 18

you compare sterilization techniques to phenol using salmonella
-if you wanna test a burning unit: pseudeumonus ariginosa (used for burn patients)
- for babies you use staphacucus arius

Question 19

what do we use instead of the phenol coefficient

Answer 19

use dilution method

Question 20

what kind of sterilization technique causes brain damage

Answer 20

wash w hexochlorophine

Question 21

what is triclosan

Answer 21

a bisphenol that is a disinfectant or biocide

Question 22

can heavy metals inhibit bacterial growth

Answer 22

yes by denaturing proteins
all heavy metals have anti-bacteria action
(Mercury is toxic and so is sillinuim)

Question 23

disinfectant against gram positive and negative compounds

Answer 23

ammonium ion and benzalkonium chloride
- damages membranes
- used in the food industry for cleaning and disinfecting

Question 24

what is cetylpyridinium chloride

Answer 24

a quaternary ammonium salt antiseptic

Question 25

what is an example of an anionic detergent

Answer 25

sodium laural solphate or sodium dodecyl
- inhibits gram positives but not negatives
- can be used as a selective agent

Question 26

what do alcohols do to bacteria

Answer 26

• damage membranes
• denature proteins
• used for cleansing in intervenous blood testing
• 70% of alcohol is more effective than higher percentages

Question 27

how do halogens kill bacteria

Answer 27

chlorine, bromine, fluorine, and iodine
- of the halogens Iodine is best because it denatures proteins by iodines the tyrosine residue

Question 28

what is chlorination

Answer 28

forms hypochloris acid which is a very strong oxidizing agent

Question 29

what are the alkylating agents

Answer 29

• formaldehyde
• glutaraldehyde: used in hospitals in alkaline solution which is sporicidal (CIDEX)
• ethylene oxide
• tend to be sporicidal

Question 30

what does ethylene oxide react with

Answer 30

amino groups of proteins and adds carbons to amio groups

Question 31

decreasing order of resistance of microorganisms to chemical biocides

Answer 31

-Most resistant
1. prions
2. endospores of bacteria
3. mycobacteria: bc of waxy material
4. cysts of protozoa
5. vegetative protozoa
6. gram-negative bacteria: because of the outer membrane
7. fungi
8. viruses without envelopes
9. gram-positive bacteria
10. viruses with lipid envelopes
-Least resistant

Question 32

how well does glutaraldehyde kill endospores and mycobacteria

Answer 32

endospores: fair
mycobacteria: good

Question 33

how does phenol kill

Answer 33

disruption of plasma membrane and denaturation of enzymes

Question 34

what kind of toxins do gram positive bacteria produce

Answer 34

exotoxins

Question 35

what kind of toxins do gram negative bacteria produce

Answer 35

endotoxins and exotoxins

Question 36

cell wall disruption by lysozymes in gram negative and positive bacteria

Answer 36

high in gram positive
low in gram negative

Question 37

inhibition by basic dyes in gram negative and positive bacteria

Answer 37

• gram-positive: high
• gram-negative: low

Question 38

susceptibility to anionic detergents in gram negative and positive bacteria

Answer 38

• gram positive: high
  -gram negative: kow

Question 39

resistance to dying in gram negative and positive bacteria

Answer 39

gram negative: low
gram positive: high

Question 40

net result of embden-myerhof pathway

Answer 40

2 atp
2 nadh

Question 41

Memorize these antiseptic moleccules they will be on the test

Answer 41