Microbiology Test 2

typical bacterial growth curve

typical bacterial growth curve

stationary phase

cells are reproducing and some cells are dying at about the same rate, so the overall population numbers stay the same

death phase

when you have bacteria dying at a faster rate than cells are reproducing

lag phase

the bacteria are metabolically active but they are not reporoducing so the cell numbers stay the same

exponential (Log) phase

in a short period of time the bacteria will replicate many times causing a large increase in cell number

bacteria that are grown or cultivated in batches have an _____________ growth phase.

additional

microbial batch growth curve

long-term stationary phase

only in the microbial batch growth curve

has a constant input of nutrients and a way to get rid of some waste products

generation (doubling) time

-the time needed for the population to double in size

-varies depending on species of microorganism and environmental changes

in ideal conditions, the generation (doubling) time can occur as quickly as ___ minutes

15

binary fission

-most bacterial cells are divided by this process

-the DNA replicated first & the cytoplasm divides last

most bacterial cells have...

single circular chromosomes

where does DNA replication occur?

At the origin site of replication

Terminus

site at which replication of DNA is terminated, located opposite of origin

Mesosomes

-look like loop-like structures of the plasma membrane

-they help to pull the chromosomes to the opposite pole of the cell to ensure that the daughter cells will each have a chromosome

what happens during cell replication?

-the septum begins to grow inward as the chromosomes move towards opposites ends of the cell via mesosome

-the septum is synthesized completely through the cell centers creating two separate cell chambers (aka daughter cells)

-some species separate completely while others remain attached.

What is the cell wall composed of?

1/2 cell wall is newly synthesized peptidoglycan and the other 1/2 is an old cell wall hemisphere and a peptidoglycan

some bacteria reprodcue by methods other than binary fission such as....

budding (ex. yeast) and multiple fission

Ftsz determines the site of _____________ growth

cell wall

How does cell wall synthesis work?

-peptidoglycan synthesis starts in the cytoplasm with the attachment of uridine diphosphate (UDP) to the sugar n-acetylglucosamine (NAG)

-NAM is transferred from UDP to bactoprenol (a carrier embedded in the plasma membrane)

-NAG is then attached to NAM: generating a NAM-NAG; the NAM-NAG units are available for insertion

-in order for NAM-NAG unites to become part of the cell wall, you need to have Autolysins degrade bonds in the existing peptidoglycan-> this permits the insertion of new NAM-NAG units

What are some environmental factors that affect microbial growth?

pH, temperature, oxygen, biofilms

What is pH?

measure of the relative acidity of a solution

acidophiles

pH 0 and 5.5

neutrophiles

pH 5.5 and 8

alkaliphiles (alkalophiles)

pH 8 and 11.5

What are some mechanisms that maintain a neutral cytoplasmic pH?

-exchange potassium for protons

-pump protons out

-synthesize acid and heat shock proteins

-change the pH of their habitat by producing acidic or basic waste product

temperature effects

bacteria have a range in which they will grow, the range varies for different types of bacteria

psychrophiles

cold loving

0-20 degrees celsius

pyschotrophs

0-35 degrees celsius

known for food spoilage in fridges

mesophiles

20-45 degrees of celsius

human pathogens are classed as ________________.

mesophiles

thermophiles and hyperthemophiles are found in _______________.

hydothermal vents in the ocean.

oxic zone

area where O2 is available

anoxic zone

where there is no O2

aerobe

requires oxygen

anaerobe

does not require oxygen, could potentially die in its presence.

obligate aerobe

requires O2

microaerophile

requires low levels of O2

facultative anaerobes

do NOT require O2 but grow better in its presence

aerotolerant anaerobes

grow with or without O2

Growing anaerobic microbes in anaerobic jar

-water is added to gas peak (gas generator envelope) to generate H2 and CO2

-carbon dioxide promotes more rapid growth of microbes

-oxygen is removed with hydrogen to form water

-this reaction is catalyzed by the palladium pellets

-the anaerobic indicator stirp methylene blue becomes colorless in absence of O2

quorum sensing

bacterial cells in biofilms communicate in a density dependent manner

what is a quorum sensing system?

symbiosis- Vibrio fischer and bioluminescence in squid

peptones

protein

extracts

aqueous extracts, usually of beef or yeast

agar

polysaccharide solidifying agent

selective media

-allow the growth of particular microorganisms, inhibiting the growth of others

-mannitol salt agar- staphylococcus

differential media

-distinguish among different groups

-blood agar- hemolytic bacteria

-EMB- lactose fermenters

Describe counting cell numbers by the spread plate

After incubation the numbers are determined by counting the colonies.

Results expressed as colony forming units (CFU) ideally approximately 25 to 250 colonies per plate.

Petroff-Hauser chamber

-a type of counting chamber

-used often to determine the Grade of milk

membrane filter technique

-bacteria from aquatic samples are trapped on membranes

-colonies grow on membrane

turbidometric measures

-light scattering

-quick, easy, sensitive

-spectrophotometer

metabolism

total of all chemical reactions in the cell

catabolism

breakdown/ degrade large molecules

anabolism

build/ synthesize large molecules

metabolism pathways can be varied

-linear

-cyclin

-branching

Catabolic reactions _______ ATP molecules.

form

anabolic reactions use ATP to _________________________.

build larger molecules

What are three ways to generate ATP?

1. substrate level phosphoylation

2. oxidative phosphorylation

3. photophosphoylation

Molecules needed for metabolism:

electron carriers picks up high energy electrons and carry them to electron transport systems

enzymes help to carry out each step in metabolic pathway.

NAD

nicotinamide adenine dinucleotide

an electron carrier

NADP

nicotinamide adenine dinucleotide phosphate

(typically used in anabolic pathways)

an electron carrier

FAD

electron carrier

flavin adenine dinucleotide

FMN

-flavin mononucleotide

-riboflavin phosphate

coenzyme Q (CoQ)

electron carrier, also called ubiquinone

cytochromes

electron carriers

used iron to transfer electrons

electron transport chain (etc)

electron carriers organized into ETC

enzymes

-lower activation energy of rxns

-speed up rate

-not changed during reaction

-binds to substrates

-some enzymes are composed more than one polypeptide

apoenzyme

protein portion of enzyme

coenzyme or cofactor

non-protein portion of enzyme

holoenzyme

apoenzyme & coenzyme

active site

where it binds to substrate

Each enzyme has specific pH and temperature optima, deveiation from optimum will __________________________.

slow enzyme activity

denaturation

loss of enzymes structure and activity when temperatures rises too much above optima

microorganisms have different sources for getting ______, ___________, and __________.

energy, electrons, and carbon

auto-

self

hetero-

from an "other" source

photo-

light

chemo-

chemicals

litho-

inorganic

-troph

feeding or eating

photolithoautotroph

carry out photosynthesis, get their energy from light and carbon from carbon dioxide

chemoorganoheterotroph

most human pathogens!

most respiration involves the use of an _____________________________.

electron transport chain

aerobic respirations final electron acceptor is _________________.

oxygen

femernation has no _________________.

electron transport chain

How many steps does aerobic respiration in prokaryotics have?

4 steps

what is the formula for glucose

C6 H12 O6

isomer of glucose is ______________.

fructose

Aerobic respiration produces ATP by.....

substrate level phosphorylation & oxidative phosphorylation

The Embden-Meyerhof Pathway

-commonly called glycolysis

-occurs in cytoplasmic matrix

-this is the most common pathway for glucose degradation

-it can function in the presence or absence of O2

How does glycolysis work?

1. addition of phosphates "primes the pump"

2. oxidation step- generates NADH

3. High-energy molecules used to synthesize ATP by substrate-level phosphorylation

What is the summary of glycolysis?

glucose + 2ADP + 2P + 2NAD-> 2 pyruvates + 2 ATP + 2NADH + 2H+

The tricarboxylic acid cycle is also known as.....

citric acid cycle, TCA cycle, and Krebs cycle

bacteria and archaeal electron transport chains are found in the ___________.

plasma membrane

bacterial and archaeal ETCs are different from mitrochondrial ETC because.......

they have different molecules and they may be shorter

in bacteria and archaea, for each NADH+H, ____ ATP are made.

3

In bacteria, ______ NADH always results in ______ATP produced at the ETS

1, 3

In bacteria, _____FADH2, results in _____ATP produced at the ETS.

1,2

What is generated at the ETS?

most of the ATP of carbohydrate catabolism (aerobic respirtation)

the atp is produced by the process of oxidative phosphorylation