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Flashcards in lecture 3- controlling microorganisms Deck (32):
1

disinfection

destroys most microbial life, reducing contamination on inanimate surfaces
-destroy vegetative (growing) cells
-doesn’t kill bacterial spores
-conditions too harsh to use on people

2

antisepsis

destroys most microbial life, reducing contamination on a living surface
-Use “antiseptics”, chemical agents that kill microbes

3

sterilization

destruction of all microbial life
-used for inanimate objects, never living tissue as too harsh

4

what are cells?

packages of water, genetics, proteins, sometimes have cell wall

5

highest resistance

-bacterial endospores
-pirons (infectious proteins)
*no moving parts, low enzymes therefore few targets to kill

6

moderate resistance

-Protozoan cysts (kind of like a spore)
- fungal sexual spores,
-naked viruses (does not have a membrane)
-resistant bacteria (like some Gram+)

7

least resistance

-growing bacterial cells (expire quickly without water)
-growing eukaryotic cells
-enveloped viruses (c/membrane - HIV)
-yeast

8

how are viruses resistant?

-dont need food
-many don't need water

9

how are bacterial spores resistant?

-some Gram-positive make spores
-don’t need food
-strong protein coat protects genetic material and enzymes inside
-low water content

10

how are some bacteria resistant?

ESP. Gram +
-thick cell wall
-resist desiccation (drying)

11

how are eukaryotes resistant?

-protozoan cysts
-fungal spores
-Strong protein coats
-Don’t need water

12

how is microbial death characterized?

-cell structures dysfunctional (irreversible damage)
-cant reproduce
-Need microbicidal agent

13

-cidal

killed

14

-static

not killed, won't grow in mass numbers, removes them

15

what affects microbial killing rate

-number of organisms (harder to kill lots - fewer cells, less sterilization time)
-type of microbial population
-concentration of decontaminating agents (less concentrated, less killing)
-mode of action for agent
-presence of solvents, organic matter, and inhibitors
-environment temp and pH

16

how do you kill microbes?

**target weaknesses**
-denaturation of:
cell wall
cell membrane
enzymes
genetic material

17

MOA: targeting cell membrane

-when cell membrane is disrupted, selective permeability is lost - cytoplasm leaks out causing cell death

18

MOA: inhibiting enzyme functioning

-proteins have a specific shape (native shape) when this is disrupted the protein becomes denatured
-enzyme active sites can't accept substrate to function

19

explain the difference between moist heat and dry heat and how they kill microbes

moist heat is for coagulation and denaturation
dry heat removes water from organisms (incineration)

*moist heat is more destructive b/c water has ability to kill proteins within organism (takes less time sterilize)

20

how does the autoclave work?

high pressure concentration of steam creating a destructive moist heat

21

what is pasteurization used for? how is it accomplished?

-disinfect beverages
-heat is applied to liquid to kill pathogens, but doesn't denature proteins (flavour and texture in tact)
-doesnt kill endospores, and it is NOT STERILE

22

what are the two methods of pasteurization?

flash: expose to 71.6°C for 15 seconds
Batch: expose to 63°C to 66°C for 30 minutes

23

MOA: Ionizing radiation

ionizing: energy from-rays, gamma-rays and high energy UV light to liberate e- from atoms

*can penetrate and get hidden microbes, can inhibit proteins

24

what is ionizing radiation used to sterilize?

food products, medical products

25

advantages of ionizing radiation

speed, penetrating power, no heat

26

Non-ionizing radiation

-causes mutations in DNA leading to cell death or function changes--> caused by low energy UV (thats why you wear sunscreen)

27

uses of non-ionizing radiation

-disinfection rather than sterilization
-Hospital rooms, operating rooms, schools, food prep areas, dental offices
-Treat drinking water or purify liquids

28

MOA: Phenols

-one initial disinfectants used
-very penetrating
-kill cells and spores and most viruses
-denature proteins, membranes, cell walls

29

MOA: Reactive ions

includes chlorine, iodine, fluorine
-very penetrating
-kill cells, spores and most viruses
-strong oxidizers: they are hungry for electrons
(denature proteins and DNA)

30

MOA: Alcohol

70% ethanol kills cells
better than 100% alcohol
b/c breaks membranes and denatures proteins.
**30% water contributes to coagulation
-Does not destroy bacterial spores
-More effective against enveloped than naked viruses

31

MOA: detergents and soaps

detergents disrupt membranes (penetrates into membrane allowing cytoplasm to leak out)
-polar and non polar portions to help penetrate into cell membranes

32

how is filtration used to decontaminate liquids

-remove cells, but not most viruses
-non-denaturing and helpful for making serum, vaccines, antibiotics, purify water