MicroBio Test 2

growth increases in the _________ of cells

number

What is binary fission?

cell division following enlargement of a cell to twice its minimum size

what is generation time?

time required for microbial cells to double in number

what does growth happen through?

binary fission

Fitsz forms contractile ring that pinches off, fueled by ________ hydrolysis

GTP

the septum is built with what protein? (contributes to divisome)

Ftsz

_________ protein is necessary for rod shape

MreB

MreB mutants are ________

spherical

cells have ______, that cut a little bit of cell wall but build in cell wall when dividing

autolysins

___________ is a lipid carrier molecule that transport the NAM/NAG/pentapeptide peptidoglycan precursor across the cytoplasmic membrane to the site of cell wall synthesis

bactoprenol

what helps to deliver building blocks across the membrane for the cell wall?

bactoprenol

what antibiotics affects transpeptidation?

penicillin

transpeptidation

glue for building blocks

the function of penicillin is to block what?

transpeptidation

what are the phases of population growth?

1. lag: at the beginning cells don't grow fast, cells adjust to environment by expressing genes
2. exponential: perfectly adjusted & ready to go, happiest time for the cells, doubling, measure generation time
3. stationary: use up all energy, cells divide at the same rate as they die, unpleasant moleculars go up, slowing down, in a flask
4. death: cell numbers start to go down, low nutrients, high toxic by product, slow down

_________ control growth rate and population density independently of one another

chemostats

what are the advantages of direct cell counts: petroff-hauser chamber?

method is fast and takes only a couple of minutes

what does direct cell counts: petroff-hauser chamber tell us?

the size of square and number of cells in volume

what is a disadvantage of direct cell counts: petroff-hauser chamber?

it is impossible to say if the cells are dead or alive by looking at them

a second method for enumerating cells in liquid samples is with a flow ________, which uses laser beams, fluorescent dyes, and electronics

cytometer

what is this the characteristics of?
- measures cells that are flowing
- different shapes of cells cause light to refract different ways
- distinguish living cells from dead (no fluorescent = dead cells)
- very thin tubing
- laser shoots light across, if their is a cell light will change
- counts how many times the laser was interrupted and that is the number of cells

measuring flow cytometry

what is an advantage to plate/colony counts?

measures concentration of cells
bullet proof guarantees to let us see how many living cells there is

what is an disadvantage of plate/colony counts?

takes a longer time, 24 hours
propagated the pathogen, so people working with it are at increased risk

serial dilution for cell counting

advantage: to see if it is anaerobic or aerobic
lower number of cells in a calm manner and then count them

What does a spectrophotometer measure?

turbidity

what are the physical requirements for bacterial growth?

temperature
pH
osmotic pressure (diffusion)

what are the chemical requirements for bacterial growth?

carbon
nitrogen, sulfur, and phosphorus
trace elements
oxygen
organic growth factor (vitamins)

thermophile

very hot
bacteria
laundry detergent

Psychrophile

like cold temp
less competition

mesophile

not very hot, not very cold
pathogens that affect us

hyperthermophile

boiling water, hot

as temperature increases growth of ______________ increases

bacteria

Molecular adaptations to thermophily

- Enzyme and proteins function optimally at high temperatures; features that provide thermal stability
- Critical amino acid substitutions in a few locations provide more heat-tolerant folds
- An increased number of ionic bonds between basic and acidic amino acids resist unfolding in the aqueous cytoplasm

microbial life in the cold

- molecular adaptations to psychrophily
- production of enzymes that function optimally in the cold:
- more a-helices than b-sheets
- more polar and less hydrophobic amino acids
- fewer weak bonds
- modified cytoplasmic membranes (high unsaturated fatty acid content

what is the difference between pH 5 and pH 7?

low pH acid, higher pH than 7 is base

osmophiles

survive in high sugar areas

halophiles

certain microorganisms adapt to survive in high salt content

xerophiles

survive in dry conditions

acidophiles

love acid/live in it but inside is neutral

buffers

special chemicals that resist change of pH

acidic

a lot of H+

basic

a lot of OH-

____________ and _________ have robust cytoplasmic membranes

acidophiles, alkaliphiles

microorganisms enjoy being in what place thinking about acid and bases?

not far from neutral

________ like the danger zone

mesophiles

_______ growth of bacteria occurs between 60 degrees Fahrenheit and 120 degrees

rapid

aerobes

these organisms need oxygen

what are examples of aerobes?

humans and animals

microaerophiles

love small concentrations of air

fulcultative anaerobes

these organisms prefer oxygen but can survive with out it

aerotolerant anaerobes

do not care about oxygen and these organisms do not need/prefer oxygen but will tolerate it

obligate anaerobes

do not need oxygen and won't survive with oxygen

differential media

make it easy to distinguish colonies of different microbes
some sort of visual change

selective media

suppress unwanted microbes and encourage desired microbes
will suppress what we don't want

enrichment culture

encourages growth of desired microbe
helps what we want but does not kill what we don't want

2 ways to preserve bacterial cultures

deep freezing : - 80 degrees celsius, addition of a cryoprotector (glycerol) is often required

lyophilization (freeze-drying): frozen (-54 Celsius to -72) and dehydrated in a vacuum

chemically defined media

exact chemical composition is known
chemical formulas

complex media

extracts and digests of yeasts, meat, or plants
nutrient broth
nutrient agar

biosafety levels

1 - no special precautions, do not cause infections in humans
2 - lab coat, gloves, eye protection, more direct hazards
3 - biosafety cabinets to prevent airborne transmission; all work will be inside cabinet, serious, lethal
4 - sealed, negative pressure, exhaust air is filtered twice

example of biosafety level 1 is

normal ecoli

example of biosafety level 2 is

salmonella, HIV

example of biosafety level 3 is

TB

example of biosafety level 4 is

small poxs

inoculum

introduction of microbes into medium

culture medium

nutrients prepared for microbial growth

sterile

no living microbes

culture

microbes growing in/on culture medium

agar

Complex polysaccharide
Used as solidifying agent for culture media in Petri plates, slants, and deeps
Generally not metabolized by microbes
Liquefies at 100°C
Solidifies at ~40°C

organic compounds will always contain what?

carbon and hydrogen

most __________ are polymers consisting of many small repeating molecules

macromolecules

The smaller repeating molecules are called ___

monomers

building of polymers is called

dehydration

dehydration remove water in order to build a -

molecular

hydrolysis

add molecular of water

during dehydration we need ________ in order to build?

energy

during hydrolysis energy is __________

released

what is the basic formula for sugar?

CH2O (carbohydrate)

carbohydrates can be classified as -

monosaccharides, disaccharides, polysaccharides

__________ are formed when 2 monosaccharides are joined in a dehydration synthesis

disaccharides

disaccharides can be broken down by?

hydrolysis

_________ consists of tens or hundreds of monosaccharides joined through dehydration synthesis

polysaccharides

where is starch found in?

plants

where is glycogen found in?

liver, animals

where is cellulose found?

plants

Where is chitin found?

insects

what is the bond that binds sugars together?

glycosidic bond

what type of bond is used to build polymers of sugar?

glycosidic bond

what are the primary components of cell membranes?

lipids

what are nonpolar and insoluble in water?

lipids

what do lipids consist of?

carbon, hydrogen, oxygen

in fats/lipids what is bond called?

ester bond

simple lipids contain what?

glycerol and fatty acids

in order to make ester bond what do we have to have?

glycerol and fatty acids

saturated fat

no double bonds
straight line

unsaturated fat

one or more double bonds in the fatty acid
curved line

examples of saturated fats

butter, bacon, lard

examples of unsaturated fats

olive oil, vegetable oil

what is an example of a complex lipid?

phospholipids

what do complex lipids contain?

C, H, O + P, N, or S

cholesterol is a membrane temperature _________ ________

fluidity buffer