Topic 6: Control of Growth

Question 1

Sterilization

Answer 1

Killing all microbial life

Question 2

Asepsis

Answer 2

Absence of contamination by unwanted organisms

Question 3

Disinfection

Answer 3

Killing the microbes that cause disease on inanimate objects

Question 4

Antisepsis

Answer 4

Disinfection on living tissue

Question 5

Thermal death point

Answer 5

Lowest temperature needed to achieve sterilization within a certain time

Question 6

Thermal death time

Answer 6

Time needed to completely eliminate a certain bacteria at a certain temperature

Question 7

Decimal reduction time

Answer 7

Only kills 90%

Question 8

Autoclaving

Answer 8

Steam under pressure and kills endospores

Question 9

Pasteurization

Answer 9

Kills pathogens but not endospores

Question 10

Ionizing radiation

Answer 10

Short wavelength, high energy damages DNA

Question 11

Non-ionizing radiation

Answer 11

Low energy with thymine dimers

Question 12

Use-dilution test

Answer 12

Metal rings dipped in bacteria are dried and placed in disinfectant to see whether the bacteria survive

Question 13

Disk-diffusion test

Answer 13

Soak paper disks in chemical to be tested

Question 14

Phenol

Answer 14

Disrupts membranes and proteins

Question 15

Halogens used for disinfecting

Answer 15

Iodine or chlorine

Question 16

Iodine

Answer 16

• Surface disinfectant

- Forms complexes with amino acids & fatty acids which inhibits protein synthesis

Question 17

Chlorine (hypochlorous acid)

Answer 17

Disrupts enzymes associated with the membrane

Question 18

Biguanides

Answer 18

• Chlorhexidine

- Attacks membranes, particularly gram positive

Question 19

Heavy metals used for disinfecting

Answer 19

Copper, zinc, silver

Question 20

Emulsifiers

Answer 20

• surface acting agents (like soap_

- Degerming

Question 21

Quaternary ammonium compounds (quats)

Answer 21

• Modifications of ammonia
• Against gram positives
• Alters plasma membrane
  (does not work against Pseudomonas)

Question 22

Aldehydes

Answer 22

Link functional groups on proteins

Question 23

Sterilizing gasses

Answer 23

Replace protein functional groups with alkyl groups

- Denatures proteins

Question 24

Most resistant prokaryote

Answer 24

Prions

Question 25

Least resistant prokaryotes

Answer 25

Viruses with lipid envelopes