5. bacterial growth and metabolism

two hours? 8 questions

generation T

time required for cell to divide or for population to double

E coli GT

20 minutes

phases of growth

1. lag

2. log

3. stationary

4. death

lag phase

making new enzymes in response to new medium

log phase

exponential growth

desired for production of products most sensitive to drugs and radiation during this period

stationary phase

nutrients becoming limiting or waste products become toxic

death rate = division rate

death phase

death exceeds division

list the G+ bacteria that are spore-forming

bacillus

clostridium

T/F G+ bacteria never form spores

FALSE

G- NEVER FORM SPORES

how is sporogenesis initiated?

lack of a critical nutrient such as alanine

takes 6-8 hours

list the contents of spores

-DNA

-protein

-ribosomes

-Ca2+ bound dipicolinic acid

endospore cortex is surrounded with _____________

keratin-like protein coat

spores what causes germination to vegetative state?

water and triggering nutrient (alanine)

90 minutes (shorter time than formation)

most pathogens grow at this optimum temperature

37ºC

pathogens are _________

mesophiles

exceptional pathogens grow at: ___ listeria monocytogenes (G+) yersinia enterocolitica (G-)

4ºC

T/F pasteurization kills most bacterial pathogens

TRUE

spores survive at higher or lower temperatures?

higher

_________ organisms prefer cold environments

psychrophilic

they're psychotic so they're opposite

__________ organisms prefer warmer temperatures

thermophilic

therm = hot

_________ organisms thrive in extremely hot environments

hyper-thermophilic

hyper = super; therm = hot

pathogens and pH relationship

prefer neutral pH

low (acidic) pH of stomach kills most pathogens

T/F bacteria all have the same O2 requirements

FALSE

vary widely in their O2 requirements

_________ require O2

strict/obligate aerobes

aerobic = oxygen

________ are killed by O2

strict/obligate anaerobes

anaerobic = no oxygen

________ grow best in presence of O2, can live without it

facultative anaerobes

facultative = optional

__________ like low O2 concentration

microaerophiles

micro = low

_______________ grow without O2, but O2 doesn't kill them

aerotolerant/indifferent

doesn't care

aerobic metabolism often generates __________ byproducts

toxic

detoxifying enzymes for O2 byproducts are ______________

-present in aerobes

-absent from anaerobes

makes sense because we only need if we're doing aerobic metabolism (using oxygen)

aerobes, microaerophiles, and facultative anaerobes have these 2 enzymes

-superoxide dismutase

superoxide + water -> oxygen + hydrogen peroxide

-catalase

hydrogen peroxide -> oxygen + water

T/F carbon source (as a growth requirement) must be complex

FALSE

can be as simple as methane (CH4)

____________ organisms require numerous supplements

fastidious

(cultured on blood agar)

T/F growth requirements or supplements are diagnostic

TRUE

major essential elements

-magnesium

-phosphorous

-potassium

-iron

-nitrogen

-sulfur

-sodium

-chloride

minor essential elements

-zn

-mn

-mo

-se

-co

-cu

list the stuff needed for growth

-carbon source

-hydrogen

-oxygen

-energy

-amino acids

-vitamins

-major essential elements

-minor essential elements (for some enzyme function)

what part of catabolism is diagnostic?

utilizing organic compounts

function of catabolism

-produce energy

-provide carbon skeletons

cellular respiration

process cells use to break down organic molecules, liberate, and capture their energy into ATP

there are 2 types of cellular respiration

aerobic: exergonic, requires oxygen

anaerobic: exergonic, does NOT require oxygen

what is an anaerobic pathway with small energy yield (not cellular respiration)?

fermentation

aerobic respiration involves a ______________ system

electron transport

what form of respiration is used by most eukaryotes and prokaryotes to obtain ATP from glucose?

aerobic respiration

what are the starting materials and products in aerobic respiration?

glucose oxidized to CO2

O2 reduced to H2O

4 stages of aerobic respiration

-glycolysis

-transition reaction forms acetyl coA

-citric acid (Krebs) cycle

-ETC, chemiosmosis, and oxidative phosphorylation

what is the end product of glycolysis under aerobic conditions?

pyruvate

how much ATP is made in glycolysis with 1 glucose molecule?

total: 4

net: 2

are steps 1 and 3 of glycolysis: endergonic or exergonic

endergonic

how much pyruvate is made in glycolysis from 1 glucose molecule?

2

what happens to the pyruvates produced by glycolysis?

enter krebs cycle

how many NADH are made during glycolysis for 1 glucose molecule?

2

how many NADH are made when glucose is metabolised?

10

what is the molecule produced from glucose that enters the krebs cycle?

acetate from acetyl coA

hexokinase

inhibited by G6-P

present in most cells

glucokinase

not inhibited by G6-P

present in liver and pancreas beta cells

fermentation

anaerobic breakdown of carbohydrates

catabolism of glucose without net oxidation

what is the final electron acceptor in fermentation?

organic molecule

how is ATP made during fermentation? how much?

substrate-level phosphorylation

2 net

who uses fermentation?

aerobic

facultative anaerobic

where does glycolysis occur?

cytoplasm

what are the products of fermentation glycolysis?

2 pyruvate

2 NADH

2 H+

2 ATP (net)

list some beneficial fermentation end products

lactic acid (yogurt)

ethyl alcohol (beer)

CO2 (bread)

yeast under anaeroboic conditions (fermentation)

glycolysis: glucose -> pyruvate -> ethanol

what does fermentation do to NADH?

NADH is oxidized back to NAD+

NAD+ can then be used in glycolysis

when does lactic acid fermentation in muscles occur?

vigorous exercise

O2 depletion

localized anaerobic conditions

what does lactic acid accumulation lead to?

muscle stiffness

after lactate fermentation occurs and aerobic conditions return, what happens?

normal aerobic respiration

lactate conversion into ATP

where does the transition step occur in prokaryotes?

cytoplasm

where does the transition reaction occur in eukaryotes?

pyruvate enters mitochondrial matrix first

the transition reaction connects ____________ to __________

glycolysis to citric acid cycle

citric acid cycle products

6 NADH

2 FADH2

2 ATP

4 CO2

________ and _______ transfer protons and electrons to ETC, resulting in ATP

NADH and FADH2

list the membrane electron carriers

-flavoproteins

-iron-sulfur proteins

-quinones

-cytochromes

the last electron carrier in ETC transfers the electron to _______

O2

how much ATP is made in total per 1 glucose molecule?

38 ATP