Exam 2 MicroBio Study Guide IN PROGRESS

FA25

what are the 3 ways to control microbial growth

1. physical and chemical (disinfectants, anitseptics)

2. chemotherapeutic drugs (antibiotics, synthetic drugs)

3. immune system and vaccines (non specific mechanisms, specific mechanisms, prevention)

what is sterilization

all forms of microbial life are destroyed includes bacterial endospores and viruses (there are no degrees to sterilization)

what is disinfection

destroys microbes on inanimate objects, getting rid of harmful microbes, NOT sterile

what is antiseptic

“against infection”, chemical disinfection of living tissues, antiseptics do not destroy the living tissues

what is sepsis

refers to the bacterial contamination

what is asepsis

the absence of significant contamination (not sterile)

what is bacteriostatic

stops growth, but does not kill

what is bactericidal

kills microorganisms

what is germicide

chemical agents that kill microbes but not necessarily the endospores

what is degerming

the process of reducing the number of microorganisms on a surface or object, typically by mechanical means

what is sanitization

sanitization is the process of reducing the microbial population on a surface or object to a level that is considered safe for its intended use

what is biocide

a substance or agent that destroys, deters, or controls, the growth of harmful microorganisms

what is germicide

any chemical agent, substance, or process that destroys microorganisms

describe filtration and how it suppresses microbial growth

passage of a substance through a screenlike material with vacuum behind filter, used for heat-sensitive materials, removes microbes that are bigger than the filtration holes

describe low temperature and how it suppresses microbial growth

it has a bacteriostatic effect, refrigeration, deep-freezing, lyophilization (freeze drying)

describe high pressure and how it suppresses microbial growth

denatures proteins (even without heat)

describe desiccation and how it suppresses microbial growth

absence of water prevents metabolism

describe osmotic pressure and how it suppresses microbial growth

uses high concentrations of salts and sugars to create hypertonic environment, causes plasmolysis

describe moist heat

• boiling/free flowing steam

  • disinfects not sterilizes

• free flowing steam

• pressurized steam (autoclaving)

  • sterilizes, 15 min will kill all organisms and their spores

one of the best methods for sterilization

• Pasteurization - reduces spoilage organisms and pathogens by heating materials for a short time

describe dry heat

• flaming (until its red hot)

• incineration (burning it)

• hot air sterilization (oven for a long time)

compare the effectiveness of moist heat and dry heat

wet steam is shorter time and less temperature because it’s easier to transfer heat with water molecules in the air rather than dry air

what are the 3 types of radiation that kill cells

there are 3 types:

• ionizing radiation

• nonionizing radiation

• microwaves

how does ionizing radiation kill cells

• (X-rays, gamma rays, electron beams)

  • ionizes water to create reactive hydroxyl radicals

  • damages DNA by causing lethal mutations

how does nonionizing radiation kill cells

• (ultraviolet)

  • damages DNA by creating thymine dimers, they try to bond with DNA and damages it

how do microwaves kill cells

kill by heat, not especially antimicrobial, radiation but transfer energy into water molecules → heats → denatures