Bacterial Metabolism

Question 1

T/F In general, bacterial cells have the same metabolic activities as eukaryotic cells?

Answer 1

T

Question 2

glycolysis review: how many moles ATP consumed vs. how many produced per mole glucose?

Answer 2

2 consumed, 4 produced per mole of glucose in glycolysis

Question 3

describe the glyoxylate shunt

Answer 3

functions similarly to the Krebs cycle but lacks some of the Krebs enzymes. consumes acetyl CoA. Basically a simplified version of the Krebs cycle with a shortcut.

Question 4

can some bacterial perform aerobic respiration/oxydative phos without the presence of oxygen?

Answer 4

YES, some bacterial can do aerobic respiration using a terminal electron acceptor other than oxygen (ie, NO3- which is nitrate and turns to N2, nitrogen gas)

Question 5

what happens if the ETC/TCA get backed up (due to lack of oxygen, for example?)

Answer 5

some of pyruvic acid formed from glucose during glycolysis is reduced using NADH: this regenerates NAD+

Question 6

How is ATP synthesized during fermentation?

Answer 6

via substrate-level phosphorylation only.

Question 7

aerobic respiration v fermentation: what are the relative levels of energy released?

Answer 7

much more energy released by respiration than by fermentation (on the order of 10x)

Question 8

describe obligate aerobes.

Answer 8

O2 is absolutely necessary for the growth of these organisms. they do not have the enzymes needed for fermentation. can’t ferment. can only respire.

Question 9

describe facultative anaerobes.

Answer 9

grow under aerobic and anerobic conditions. they grow better aerobically than anaerobically. may do both at the same site. contain a functional respiratory system and also have fermentative capacity.

Question 10

describe obligate anaerobes.

Answer 10

can gain energy only from fermentation mechanisms; do not possess cytochromes or an ETC. cannot grow in the presence of 02.

Question 11

what do obligate anaerobes produce on exposure to 02? how does this occur?

Answer 11

hydrogen peroxide – created because they contain flavins that produce peroxide when O2 is around. ROS from H202 can damage DNA and proteins.

Question 12

describe catalase. do anaerobes contain it? aerobes?

Answer 12

obligate anaerobes lack catalase, which is an enzyme which decomposes H202. Most aerobes contain catalase.

Question 13

describe superoxide dismutase.

Answer 13

highly reactive, free radical reactive form of oxygen (02-) formed by flavoenzymes. breaks down superoxide.

Question 14

describe aerotolerant anaerobes

Answer 14

grow exclusively via fermentation, but are indifferent to oxygen and can grow in air. do not have resp system, are not capable of oxidative phosphorylation.

Question 15

describe microaerophiles

Answer 15

organisms that will tolerate oxygen only if it is at a lower concentration than found in air (5% rather than 20%). require special growth conditions to culture.

Question 16

where do anaerobes exist within a host?

Answer 16

anaerobic conditions exist in mouth or urinary tract – can grow in tissue we usually think of as aerated, because other bacteria are present OR host is using up all the air.

Question 17

what do most microbes use as a growth substrate?

Answer 17

glucose

Question 18

glucose is a monosaccharide or disaccharide? what about lactose?

Answer 18

gluc: mono. lactose: disaccharide, requires cleavage by a glactosidase prior to catabolism

Question 19

name organisms that can use either glucose or lactose as a substrate (3)

Answer 19

E coli, Klebsiella, citrobacter

Question 20

organisms that can use glucose as a substrate but NOT lactose (2)

Answer 20

salmonella, shingella

Question 21

organisms that cannot use glucose or lactose as a growth substrate (1)

Answer 21

pseudomonas

Question 22

which types of aerobes have catalase and superoxide dismutase?

Answer 22

obligate aerobes, facultative anaerobes. NOT obligate anaerobes.

Question 23

glucose to CO2 and H2O: oxidation or reduction?

Answer 23

oxidation, because glucose is losing H. oxidizes to pyruvate.

Question 24

during which process do the bacteria make ATP via substrate level phosphorylation?

Answer 24

glycolysis

Question 25

during which process do the bacteria make ATP via oxidative phosphorylation?

Answer 25

electron transport chain.

Question 26

besides generating ATP, what can the electron gradient be used for?

Answer 26

cellular motility, and also pumping out/efflux of antibiotics.

Question 27

describe what happens to NAD/NADH and FADH/FADH2 in glycolysis and fermentation

Answer 27

Glycolysis generates reduced species (NADH and FADH2) and Fermentation recycles them so that glycolysis can take place again. Glycolysis: NAD+ -> NADH, FADH -> FADH2.
Fermentation: NADH -> NAD+.

Question 28

name 2 common products of fermentation

Answer 28

lactic acid, ethanol. NOT pyruvate, since pyruvate is the result of glycolysis.

Question 29

how can lactic acid production affect the host human?

Answer 29

resulting low pH discourages growth of competing organisms. ie, in vagina, low pH environment protects against yeast.

Question 30

how does the formation of butyric acid affect the host?

Answer 30

has very unpleasant odor, can be diagnostic. can be protective against intestinal pathogens such as E Coli.

Question 31

how does the formation of propionic acid affect the host?

Answer 31

will ferment lactate to acetic acid, Co2, and propionic acid. used in manufacture of Swiss cheese. thought to be pathogenic -> acne.

Question 32

describe mixed acid fermentations

Answer 32

generally used by enteric microbes (intestinal) because 02 is limited so need to do fermentation. mixed products can include H2, formic acid, acetic acid, succinic acid.