med term chapter 2

what is binary fission

how on cells divides

what are the 5 stages of binary fission, in order?

cell elongation

chromosome duplication

chromosome segregation

septum formation

cell separation

what is generation time

how fast a population can double

why is bacterial population growth exponential

each division double the population

why dose tuberculosis require a long antibiotic treatment course

it divides once every 15-20 hours so antibiotics kill bacteria most effectively when they are actively dividing- a slow dividing pathogen spends most of its time dormant and therefore resistant to the drug effect.

what is an endospore

a dormant highly resistant structure produce inside the vegetative cell

why is an endospore not a reproductive structure

its preserves genetic material (survival not reproduction)

what conditions destroyed endospore

by pressurized steam at 121 degrees Celsius and for a minimum of 15 minutes

what are 6 stages of sporualtion, in order

Axial filament formation

Asymmetric septum

Engulfment

Cortext synthesis

Spore coat deposition

Lysis and release

what conditions trigger endospore germination

Favorble conditions

• Nutrience

• warmth

• moisture

what temperature range define psychrophiles, mesophiles, and thermophiles

Psych: cold <15 degrees celsius

Meso: mod 20-40 degrees celsius

thermo: heat 50-60 degrees celsius

what ph range defines acidophiles, neutrophils, and alkaliphiles

acid <7 pH

neutral =7pH

alka >7 pH

how do the four oxygen use categories differ

Areo: needs O2

Ana": toxin O2

Facult: with without O2

Micro: low O2

why most humans pathogen mesophiles and neutrophiles

the human body temp is similar to mesophile, and the blood and tissue temp are similar to neutrophile.

How dose high salt or sugar inhibit bacterial growth

by sucking all of the water out of the cell

what 3 properties are used to classify growth media

Physical form

Nutritional composition

Functional Classification

what is the main advantage and limitation of liquid broth

• Used to grow large quantities of bacteria quickly

• Cannot separate individual species, all organism in the samples grown together

(browth = growth throughout liquid)

why is solid agar essential for isolating pure cultures

Bacteria on a solid surface stay in place and divide into visible colonies

(agar = separate colonies)

how do defined and complex media differ

Contain ingredients of variable or unknown composition -typically digest of animal tissue or yeast extract

(Complex Media = variable ingredients)

what is the function of selective media

contains ingredients that inhibits (stop/prevent) growth of unwanted organisms while permitting the target to grow.

(selective media = who can grow

what is the function of differential media

Contains indicators that cause different organisms to produce visibly different colony appearances.

(differential media = how growth looks)

how does MacConkey agar select for Gram-negitive bacteria

How dose MacConkeu agar distinguish lactose fermentation

bile salts and crystal violet inhibits Gram-positive bacteria, leaving only Gram-negative to grow

what is bacterial isolation

The process of separating a single bacterial species from mixed samples and obtaining a pure cultures- a population of genetically identical cell descended from one organism.

what is a pure culture

they are required before a bacterium can be identified, characterized, or tested for antibiotic susceptibility

what is the principle of streak plate method

progressive dilution of a mixed sample across the surface of a solid agar plate until individual cells are separated far enough apart to from discrete colonies

why is the loop reflamed between streak plate quadrants

The loop is reflamed and cooled; a few strokes are made through the end of the first quadrant in the second-picking up fewer bacteria with each pass.

what is a bacterial colony

How do pour plate and spread plate method differ

the poor plate is surface and embedded colonies while spread plate is surface only

what four feature describe colony morphology

size

color

edge

texture