Control - Physical and Chemical

Question 1

What is the definition of sterilization?

Answer 1

Destruction of all living microbes spores and viruses

Question 2

How do sterile objects become contaminated?

Answer 2

When exposed tp air and surroundings

Question 3

What is the definition of sanitization?

Answer 3

Reeduction in the number of pathogens or discourages their growth
-not killing them all

Question 4

What is the most common physical control of microbial growth?

Answer 4

Heat

-temps above the growth range cause proteins and nucleic acids to be destroyed

Question 5

What is the thermal death point?

Answer 5

The minimum temp at which it dies in a given time period

Question 6

What is dry heat?

Answer 6

Requires long periods of exposure to high temps

-heat changes microbial proteins and removes water slowly burning the microbe

Question 7

What is moist heat?

Answer 7

(like boiling water) is faster and effective at a lower temperature than dry heat
-kills microbes by denaturing their proteins

Question 8

Why is boiling water sometimes not effective in sanitizing?

Answer 8

May not kill all sores or inactivate all viruses

Question 9

What is pasteurized steam?

Answer 9

Used in an autoclave as a more dependable way to sterilize a variety of objects

Question 10

What is an prevacuum autoclave?

Answer 10

Decreases cycle time and exposure of sensitive materials for steam
-uses wet heat to reach a higher temp. The steam is pumped in to increase pressure and allows for water to boil at a higher temp

Question 11

Why are special indicator bacteria used for autoclaves?

Answer 11

Included in the autoclave to yes that it reached proper sterilizing conditions at all points in the chamber

Question 12

What is the purpose of a flexible tube?

Answer 12

To bend to the pressure in the autoclave, breaking the testable on the inside with the medium for the spore strip to use

Question 13

What is pasteurization used for?

Answer 13

rHeating it to a high temp then immediately cooling it to reducing bacterial populations in food and drink

• reduces the chances of spoilage and disease
• bacterial spores not affected by pasteurization

Question 14

Why is filtering effective in sterilizing?

Answer 14

If the substance can not be heat treated, filtering lets water pass but has small enough holes to keep bacteria/virus out

Question 15

Why is UV light used to control growth?

Answer 15

Causes thymine molecules to link together in DNA

-errors in protein synthesis and impairment of chromosome replication

Question 16

What are other types of radiation that can sterilize materials?

Answer 16

X-rays and gamma rays both force electrons out of microbial molecules

Question 17

What are thee 3 preservation methods to slow spoilage by microorganisms in foods?

Answer 17

Drying: removing water necessary for microbes to live
Salting: causes water to diffuse out of organisms by osmosis
Low Temperature: Lowering microbial growth rates at colder temperatures

Question 18

What does chemical control usually involve?

Answer 18

Disinfection

-chemical agents rarely achieve sterilization but they do disinfect

Question 19

What are chemical control methods dependent on?

Answer 19

Depend on the object being treated

Question 20

What are the 3 forms of chemical control?

Answer 20

Antiseptic: kill pathogens on living tissue
Disinfectant: Used on surfaces
De-germing: Removing organisms from an objects surface

Question 21

What makes a disinfectant/antiseptic useful?

Answer 21

• Kill or slow growth of organism
• Soluble in water or alcohol
• Long shelf life
• Used in dilute form
• Acts in a short time
• Odourless

Question 22

What is the phenol coefficient?

Answer 22

Sets the chemical phenol as 1.0 when used as a control agent and other chemicals are prepared at dilutions in test tubes which approximate their usage concentration and are compared against dilutions f phenol for ability to kill microbes
-cleaner strength

Question 23

What is the disk diffusion method?

Answer 23

Examines the effect of different chemical agents against a specific bacterium

Question 24

How du halogens control microbial growth?

Answer 24

Oxidize proteins

-Ex: Cl and Iodine

Question 25

How do phenols control microbial growth?

Answer 25

Compounds denatured proteins

Question 26

how do heavy metals interfere with microbial growth?

Answer 26

Interfere with microbial metabolism

Question 27

How do alcohols affect microbial growth?

Answer 27

Denatures proteins and disrupts membranes

Question 28

What do soaps and detergents act as?

Answer 28

Surface active agents

Question 29

Purpose of soap?

Answer 29

Removes microbes by emulsifying and solubilizing particles on the skin

Question 30

Purpose of detergents?

Answer 30

Surfactants

-cause cytoplasm leakage

Question 31

What does hydrogen peroxide do to microbes?

Answer 31

Damages cellular components

-rxn produces O2 which is effective against anaerobic bacteria

Question 32

What are Aldehydes?

Answer 32

Cause cross linking that inactivates proteins

Question 33

What are ethylene oxides?

Answer 33

Effective at removing microbes but carcinogenic and explosive

Question 34

What is chlorine dioxide?

Answer 34

Non toxic and non carcinogenic gas

Question 35

What are positively charged (cationic) detergents used for?

Answer 35

Sanitize food utensils and surfaces

Question 36

What are negatively charged detergents (anionic) used for?

Answer 36

Laundry cleaning and household products

Question 37

What are dyes used for?

Answer 37

Antimicrobial agent

-first used this to kill bacteria

Question 38

What is the most common dye used for microbial growth?

Answer 38

Crystal violet is used against gram positive bacteria

Question 39

What are halogens?

Answer 39

Powerful antimicrobial agents

-Chlorine, Iodine, Bromine