Microbiology Test 2

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typical bacterial growth curve

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1

typical bacterial growth curve

<p></p>
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2

stationary phase

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

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3

death phase

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

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lag phase

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

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exponential (Log) phase

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

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6

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

additional

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microbial batch growth curve

<p></p>
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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

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generation (doubling) time

-the time needed for the population to double in size

-varies depending on species of microorganism and environmental changes

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10

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

15

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11

binary fission

-most bacterial cells are divided by this process

-the DNA replicated first & the cytoplasm divides last

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most bacterial cells have...

single circular chromosomes

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where does DNA replication occur?

At the origin site of replication

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Terminus

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

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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

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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.

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17

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

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18

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

budding (ex. yeast) and multiple fission

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19

Ftsz determines the site of _____________ growth

cell wall

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20

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

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21

What are some environmental factors that affect microbial growth?

pH, temperature, oxygen, biofilms

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22

What is pH?

measure of the relative acidity of a solution

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acidophiles

pH 0 and 5.5

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neutrophiles

pH 5.5 and 8

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alkaliphiles (alkalophiles)

pH 8 and 11.5

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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

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27

temperature effects

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

<p>bacteria have a range in which they will grow, the range varies for different types of bacteria</p>
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psychrophiles

cold loving

0-20 degrees celsius

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pyschotrophs

0-35 degrees celsius

known for food spoilage in fridges

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mesophiles

20-45 degrees of celsius

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31

human pathogens are classed as ________________.

mesophiles

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32

thermophiles and hyperthemophiles are found in _______________.

hydothermal vents in the ocean.

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33

oxic zone

area where O2 is available

<p>area where O2 is available</p>
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anoxic zone

where there is no O2

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aerobe

requires oxygen

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anaerobe

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

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obligate aerobe

requires O2

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microaerophile

requires low levels of O2

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facultative anaerobes

do NOT require O2 but grow better in its presence

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aerotolerant anaerobes

grow with or without O2

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41

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

<p>-water is added to gas peak (gas generator envelope) to generate H2 and CO2</p><p>-carbon dioxide promotes more rapid growth of microbes</p><p>-oxygen is removed with hydrogen to form water</p><p>-this reaction is catalyzed by the palladium pellets</p><p>-the anaerobic indicator stirp methylene blue becomes colorless in absence of O2</p>
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42

quorum sensing

bacterial cells in biofilms communicate in a density dependent manner

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43

what is a quorum sensing system?

symbiosis- Vibrio fischer and bioluminescence in squid

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44

peptones

protein

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45

extracts

aqueous extracts, usually of beef or yeast

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agar

polysaccharide solidifying agent

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selective media

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

-mannitol salt agar- staphylococcus

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48

differential media

-distinguish among different groups

-blood agar- hemolytic bacteria

-EMB- lactose fermenters

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49

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.

<p>After incubation the numbers are determined by counting the colonies.</p><p>Results expressed as colony forming units (CFU) ideally approximately 25 to 250 colonies per plate.</p>
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50

Petroff-Hauser chamber

-a type of counting chamber

-used often to determine the Grade of milk

<p>-a type of counting chamber</p><p>-used often to determine the Grade of milk</p>
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51

membrane filter technique

-bacteria from aquatic samples are trapped on membranes

-colonies grow on membrane

<p>-bacteria from aquatic samples are trapped on membranes</p><p>-colonies grow on membrane</p>
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52

turbidometric measures

-light scattering

-quick, easy, sensitive

-spectrophotometer

<p>-light scattering</p><p>-quick, easy, sensitive</p><p>-spectrophotometer</p>
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53

metabolism

total of all chemical reactions in the cell

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catabolism

breakdown/ degrade large molecules

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anabolism

build/ synthesize large molecules

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metabolism pathways can be varied

-linear

-cyclin

-branching

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57

Catabolic reactions _______ ATP molecules.

form

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58

anabolic reactions use ATP to _________________________.

build larger molecules

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59

What are three ways to generate ATP?

1. substrate level phosphoylation

2. oxidative phosphorylation

3. photophosphoylation

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60

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.

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NAD

nicotinamide adenine dinucleotide

an electron carrier

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NADP

nicotinamide adenine dinucleotide phosphate

(typically used in anabolic pathways)

an electron carrier

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FAD

electron carrier

flavin adenine dinucleotide

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FMN

-flavin mononucleotide

-riboflavin phosphate

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coenzyme Q (CoQ)

electron carrier, also called ubiquinone

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cytochromes

electron carriers

used iron to transfer electrons

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electron transport chain (etc)

electron carriers organized into ETC

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enzymes

-lower activation energy of rxns

-speed up rate

-not changed during reaction

-binds to substrates

-some enzymes are composed more than one polypeptide

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apoenzyme

protein portion of enzyme

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coenzyme or cofactor

non-protein portion of enzyme

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holoenzyme

apoenzyme & coenzyme

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active site

where it binds to substrate

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73

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

slow enzyme activity

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denaturation

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

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75

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

energy, electrons, and carbon

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auto-

self

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hetero-

from an "other" source

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photo-

light

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chemo-

chemicals

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litho-

inorganic

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-troph

feeding or eating

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photolithoautotroph

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

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chemoorganoheterotroph

most human pathogens!

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84

most respiration involves the use of an _____________________________.

electron transport chain

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85

aerobic respirations final electron acceptor is _________________.

oxygen

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86

femernation has no _________________.

electron transport chain

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87

How many steps does aerobic respiration in prokaryotics have?

4 steps

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88

what is the formula for glucose

C6 H12 O6

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89

isomer of glucose is ______________.

fructose

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90

Aerobic respiration produces ATP by.....

substrate level phosphorylation & oxidative phosphorylation

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91

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

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92

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

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93

What is the summary of glycolysis?

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

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94

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

citric acid cycle, TCA cycle, and Krebs cycle

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95

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

plasma membrane

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96

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

they have different molecules and they may be shorter

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97

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

3

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98

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

1, 3

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99

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

1,2

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100

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

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