Chapter 7: Control of Microbial Growth

Question 0

commercial sterilization

Answer 0

heat enough to kill clostridium botulinum, but doesn’t degrade food quality

Question 1

sterilization

Answer 1

removal of all microbes from an object

Question 2

disinfection

Answer 2

destroy harmful microbes, antiseptic-used on living tissue(our skin)

Question 3

sanitization

Answer 3

lower microbe levels to public health levels

Question 4

cide=kill

Answer 4

germicide, fungicide, virucide

Question 5

“stat” “stasis”

Answer 5

inhibits growth

bacteriostasis-stops bacterial growth

Question 6

sepsis

Answer 6

bacterial contamination (septic tanks)

Question 7

factors that can influence the effectiveness of antimicrobials are…?

Answer 7

• environmental: presence of organic matter that inhibitis chemicals
• time: some antimicrobials require more time
• microbe characteristics

Question 8

mechanisms of killing microbes:

Answer 8

• damaging the plasma membranes causing cellular components to leak
• break bonds between proteins
• damage the cell’s DNA or RNA

Question 9

physical methods of killing microbes

Answer 9

1. heat
2. moist heat
3. pasteurization
4. dry heat
5. filtration
6. low temperatures
7. high pressure
8. desiccation
9. osmotic pressure
10. radiation

Question 10

heat method of destroying microbes

Answer 10

sterilization, denatures enzymes

Question 11

thermal death point

Answer 11

lowest temp. that kills all microbes in a suspension in 10 minutes

Question 12

thermal death time

Answer 12

minimal length of time for all bacteria to be killed

Question 13

decimal reduction time

Answer 13

time in which 90% of bacteria will be killed

Question 14

moist heat method

Answer 14

denatures proteins, boiling kills bacterial pathogens, viruses, fungi within 10 min (autoclave)

Question 15

pasteurization

Answer 15

eliminates pathogens and lowers microbial numbers. high temp short time(15 sec) (milk, ice cream, yogurt, etc)

Question 16

dry heat method

Answer 16

kills by oxidation effects, flaming (bactoincerator)

Question 17

filtration method

Answer 17

pass liquid through filter material, pores retain microbes, easy and fast. uses vacuum to force liquid through a filter

Question 18

low temperature method

Answer 18

most pathogens cannot grow in low temperatures

Question 19

high pressure method

Answer 19

alters proteins and carbs, inactivation of growing cells, endospore resistant

Question 20

desiccation method

Answer 20

depletion of water, microbes are viable but cannot grow (lyophilization)

Question 21

osmotic pressure method

Answer 21

salts and sugars create a hypertonic environment causing the water to leave the cell

Question 22

radiation method

Answer 22

uv light damages the DNA

Question 23

chemical methods

Answer 23

control growth, but most do not kill all microbes (concentration is important, material being disinfected)

Question 24

halogens used to kill microbes

Answer 24

iodine-impairs protein synthesis and membranes
chlorine-forms hypochlorous acid when added to water (inhibits enzymes)
alcohols-protein denaturation
heavy metals-denatures proteins

Question 25

surface-active agents (surfactants)

Answer 25

decrease surface tension (soaps and detergents)

Question 26

peroxygens chemical method

Answer 26

oxidizing, hydrogen peroxide, peracetic acid, benzoyl peroxide

Question 27

the removal or destruction of all forms of microbial life is called…

Answer 27

sterilization!

Question 28

which of the following described the pattern of microbial death?

Answer 28

the cells in a population die at a constant rate

Question 29

to sterilize heat-labile solutions, one should use…?

Answer 29

filtration

Question 30

which of the following are used to mechanically remove microbes through scrubbing?

Answer 30

detergents