Microbio Lab Exam 2

A hypertonic environment is deadly to bacterium, why?

bacteria rapidly lose water and plasmolyze.

A hypotonic environment is OPTIMAL for bacterium, why?

bc their cell wall prevents overinflation of the cell wall and cell rupture from consuming water

antiseptics

chemicals used on living surfaces to kill/ inhibit bacterial growth

disinfectants 

chemicals used on inanimate surfaces to kill/ inhibit bacterial growth

antibiotics

chemicals used in the treatment of disease

are antiseptics, disinfectants, and antibiotics bactericidal?

any of them could be, or they could also be bacteriostatic depending on the agent involved. 

Microaerophile  (4)

reduced O2, increased CO2 preferred

deep ocean muds 

live in human body tissue

grow near bottom of read zone, streamers dangling to the bottom in thioglycollate 

obligate anaerobe (4)

no O2 tolerated

deep ocean muds

smelly end product 

grow in clear zone of thioglycollate 

aerobe (4)

grown in normal amount of O2 in air

adapted for surface of skin

produce H2O at end of ETC

grow at red zone in thioglycollate 

facultative (5)

any O2 lvl usable

deep ocean muds

extensive set of energy producing enzymes

makes H2O at end of ETC

grow throughout thioglycollate

narrow spectrum antibiotic

specific for one genus or category of bacteria

broad spectrum antibiotic

affect many categories of organisms, affects structures and processes common to many bacteria

zone of inhibition

clear area around a bactericidal agent when placed on a swabbed plate, size of zone shows effectiness of agent is compared to others tested under same conditions.

resazurin in thioglycollate

redox indicator, colorless in oxygen free environment, red in presence of oxygen

generator in Gas-Pak

releases CO2 and H2 into gas-pak, H2 binds to O2, CO2 will make microaerophiles grow better within jar.

methylene blue in gas-pak

redox indicator, colorless in absence of oxygen, blue in presence of oxygen

pAmp in transformation experiment

plasmid coding for resistance to the drug ampicillin

pellicle

skim of growth on surface

turbidity

uniform dispersion of bacteria within liquid leading to cloudiness

sediment

settled at the bottom

margin on a colony

characteristic requiring you to look at the edge of the colony, could be jagged, branched, etc.

multiple quadrants and flamings during isolation streaking

allows number of organisms to diminish by wiping off cells during streaking, and killing with the flame between streaking.

psychrophile

grow in a cold environment ranging from 5-20 degrees celcius

mesophiles

grow in moderate temperatures ranging from 20-45 degrees celcius

thermophiles

grow in hot environments 45 degrees celcius and higher

3 factors influencing size of zone of inhibition

diffusability of agent, time of incubation, temp of incubation

pure culture

single species of bacteria

aerobes

dependent of oxygen

anerobes

do NOT need oxygen

green metallic on EMB plate

E.coli, gram -, lactose fermenter

Kirby Bauer method

method used to determine the effectiveness of an antibacterial agent

when studying drug sensitivities, you inoculate the plate for WHAT kind of growth?

confluent growth

a large zone of inhibition shows that the drug is…

effective even at low concentrations

a small zone of inhibition shows that the drug is…

only effective at high doses which is dangerous for patients

ingredient that slows down oxygen as it enters Na thioglycollate broth

agar

redox indicator in gas pak

methylene blue

ingredient included in special agar to test if a pAmp plasmid worked

ampicillin

redox indicator in Na thioglycollate broth

resazurin

bacterium capable of receiving new DNA pieces

competent

abnormal molecule formed in response to uv rays

thymine dimers

general Characteristics of colonies

size, shape, margin, elevation, color

general Characteristics slants

amount, shape, odor, opacity, color