Exam 2 deck 1

Question 1

Sepsis

Answer 1

Bacterial contamination

Question 2

3 ways to control microbial growth

Answer 2

1) Physical and chemical methods
2) Chemotherapeutic drugs
3) Immune system and vaccines

Question 3

Disinfection

Answer 3

Destroys microbes on inanimate object –> only kills harmful microbes

Question 4

Antiseptic

Answer 4

Chemical disinfection of living tissue

e.g. iodine

Question 5

Sterilization

Answer 5

kills all forms of microbes, including endospores and viruses

Question 6

Germicide

Answer 6

Chemical agent that kills microbes, but not necessarily endospores

Question 7

Bacteriostatic microbial suppression

Answer 7

stops growth, but doesn’t kill

Question 8

Bactericidal microbial suppression

Answer 8

kills microbes

Question 9

What affects the rate of microbial death?

Answer 9

1) the number of microbes
2) Temperature (disinfectants’ work increases at higher temps, but microbes grow slower at lower temps)
3) Type of microbe (vegetative cells are least resistant)
4) Physiological state of microbe (cells in “log” phase are most succeptible)
5) cell environment (organic matter could offer protection)

Question 10

How does heat control microbial growth?

Answer 10

It denatures the enzymes in the microbes

Question 11

Thermal Death Point

Answer 11

lowest temperature at which all cells in a liquid culture will be killed within 10 minutes

Question 12

Thermal Death Time

Answer 12

Minimum time for all bacteria in a liquid culture to be killed at a particular temperature

Question 13

Decimal Reduction Time

Answer 13

Minutes to kill 90% of a specific population of bacteria at a given temperature

Question 14

Moist Heat Examples

Answer 14

Boiling
Free flowing steam
Pressurized steam (autoclave)

Question 15

How does boiling/ free flowing steam affect microbes?

Answer 15

Disinfects, but doesn’t sterilize

Question 16

How does pressurized steam affect microbes?

Answer 16

It sterilizes

• at 15 psi the steam reaches 121 C
• 15 minutes will kill all organisms and spores
• the pressure prevents the liquid from boiling

Question 17

What is a word for low heat treatment?

Answer 17

Pasteurization

Question 18

Explain High-Temp Short-Time and Ultra-High-Temp

Answer 18

HTST is 72 C for 15 seconds

UHT is 140 C for 4 seconds

Question 19

What kind of organisms can survive pasteurization?

Answer 19

Thermoduric organisms

Question 20

What happens chemically when something burns?

Answer 20

It is oxidized

Question 21

3 types of dry heat

Answer 21

Flaming, incineration, and hot air sterilization

Question 22

Filtration

Answer 22

• Passage of substance through scree-like filter
• used for heat-sensitive materials
• we want the liquid, not the microbes

Question 23

What kind of affect does low temperature have on microbes? Which microbes are immune to this?

Answer 23

It has a bacteriostatic affect and psychrotrophs are immune

Question 24

What affect does high pressure have on microbes?

Answer 24

It denatures proteins

Question 25

What does desiccation do?

Answer 25

Lack of water prevents metabolism

usually makes bacteria dormant, but doesn’t kill them

Question 26

What does osmotic pressure do?

Answer 26

It creates a hypertonic environment, causing plasmolysis. This prevents the bacteria from replicating

Question 27

3 Types of radiation

Answer 27

Ionizing, non-ionizing, and microwaves

Question 28

Ionizing radiation

Answer 28

• ionizes water to make reactive hydroxyl radicals

- Damages DNA by causing lethal mutations which prevent the cell from making necessary enzymes

Question 29

Non-ionizing radiation

Answer 29

• Creates thymine dimers

- polymerase can’t do its job, so DNA is not transcribed

Question 30

Microwaves

Answer 30

kill by heat, but not especially antimicrobial