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MICR 2430 > TOPIC 6: Metabolism > Flashcards

TOPIC 6: Metabolism Flashcards

1
Q

how have microbes been used in industry?

A

to produce nutrient supplements (amino acids, vitamins)
degrade environmental pollutants
produce biofuels (ethanol, biodiesel, H2)

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2
Q

why should we study microbial metabolism?

A

to develop appropriate nutrient and environmental conditions to grow them in lab
microbial metabolism plays key roles in elemental cycles on earth
they are the basis of many diagnostic tests for identification of bacteria in academic, industrial, and clinical labs

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3
Q

what is MataCyc?

A

a database of experimentally elucidated metabolic pathways from all domains of life

contains 3,153 pathways, 19,020 reactions and 19,372 metabolites

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4
Q

what is catabolism?

A

breakdown of complex molecules into smaller ones
RELEASES energy –> provides energy for anabolism

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5
Q

what is anabolism?

A

reactions that build cells
REQUIRES ENERGY

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6
Q

what carbon sources can organisms get energy from?

A

autotrophs - carbon dioxide
heterotrophs - organic carbon

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7
Q

what sources can organisms get ATP?

A

photo - sunlight/photons
chemolitho - minerals
chemoorgano - organic compounds

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8
Q

how are plants and animals classified metabolically?

A

humans = chemoorganoheterotrophs
plants = photoautotrophs

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9
Q

what nucleotide carries energy for protein synthesis?

A

guanosine triphosphate (GTP)

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10
Q

what is NADH?

A

nicotinamide adenine dinucleotide
carries two or three times as much energy as ATP
donates and accepts e-
NADH is the reduced form, NAD+ is the oxidized form

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11
Q

what is the reduction reaction of NAD+?

A

NAD+ + 2H+ +2e- –> NADH + H+
delta G = 62kJ/mol

reaction requires ENERGY IMPUT, not spontaneous

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12
Q

what is FADH2?

A

flavine adenine dinucelotide
coenzyme that transfers electrons
FADH2 is the reduced form, FAD is the oxidized form

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13
Q

what compounds can chemoorganotrophs get energy from/

A

polysaccharides
lipids
peptides
aromatic molecules

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14
Q

can compounds produced by TCA be used in other pathways?

A

yes

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15
Q

what is the central molecule that sources of energy are converted to?

A

acetyl coA

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16
Q

what are the two parts of glycolysis?

A

preparative: no ATP produced, 2 ATP molecules used

SUBSTRATE LEVEL PHOSPHORYLATION: formation of ATP directly from the pathway

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17
Q

what is the net energy gain of glycolysis?

A

ATP = +2
NADH = +2
pyruvate = +2

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18
Q

what are the differences between the ED pathway and glycolysis?

A

in the ED pathway:
1. only 1ATP used in the preparative stage
2. 1 NADPH produced in the preparative stage
3. 6C sugar is broken into 1 molecule of glyceraldehyde-3-phosphate and 1 pyruvate, producing 1 ATP and 1 NADH

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19
Q

what type of bacteria use the ED pathway?

A

gut microbiota

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20
Q

what is the net gain of the ED pathway?

A

1 ATP
1 NADPH
1 NADH

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21
Q

what are the two fates of pyruvate?

A

fermentation or the krebs cycle

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22
Q

what is fermentation?

A

complete catabolism without the ETC and a terminal electron acceptor

no ATP produced

hydrogens form NADH + H+ are transformed back to NAD+ for use in glycolysis (fermentation regenerates NAD+ from NADH)

could produce ethanol or lactic acid

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23
Q

why does fermentation need to happen?

A

concentration of NADH cofactors are limited in the cell; if they are all in the NADH form then glycolysis cannot proceed

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24
Q

what is the net energy gain from glycolysis and fermentation

A

net gain of ATP = +2
net gain of NADH = 0

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25
do humans ferment?
YES during high intensity exercise, there's not enough O2 for ETC --> get energy from glycolysis and lactic acid cycle
26
where does the Krebs cycle occur?
prokaryotes = cytoplasm eukaryotes = mitochondria
27
how does glucose catabolism connect with the TCA?
through pyruvate breakdown to acetyl-CoA and CO2 acetyl-coA enters TCA cycle by condensing with the 4C oxaloacetate to form citrate it is eventually converted to Co2
28
what is produced after the Kreb's cycle?
2 ATP 8 NADH 2 FADH
29
what is the net energy gain after glycolysis and the krebs cycle?
4 ATP 10 NADH 2 FADH2
30
what is produced from each molecule of pyruvate in the TCA?
3 CO2 via decarboxylation 4 NADH from redox reactions 1 FADH2 from redox 1 ATP (or GTP) is produced by substrate level phosphorylation
31
what is the proton motive force?
transfer of H+ through a proton pump generates an electrochemical gradient of protons drives the conversion of ADP to ATP by ATP synthase aka chemisosmotic theory
32
how os energy stored when protons are pumped across the membrane?
electrical potential - arises from the separation of charge between the cytoplasm and solution outside the cell membrane pH difference - log ratio of external to internal chemical concentration of H+
33
what does delta p dive?
ATP synthesis roation of flagella uptake of nutrients efflux of toxic drugs
34
what is the formula for Gibb's free energy?
delta G = -n F delta E negative delta G = spontaneous
35
what redox pair generates more energy: NAD+ and O2 or FAD+ and O2?
NAD+
36
how many molecules of ATP does NADH make in the ETC?
3
37
how many molecules of ATP does FADH2 make in the ETC?
2
38
what is the total number of ATP generated from one molecule of glucose after the ETC?
38 (+4 ATP from glycolysis, 10x3 from NADH, 2x2 from FADH2)
39
what is it called when bacteria uses an electron acceptor that isn't O2?
anaerobic oxidation ex. NO3- + 2e- + 2H+ --> NO2- + H2O
40
are more or fewer molecules of ATP be produced from NAD+/NADH and NO3-/NO2- vs NAD+/NADH and O2/H2O?
fewer however, the delta G for NO3- is more favourable than O2
41
where is most of the energy in glucose stored?
in the form of reducing equivalents (ex. electrons)
42
how can ATP be generated?
substrate level phosphorylation - occurs in glycolysis or krebs cycle oxidative phosphorylation - through ETC; conversion of reducing coenzymes to energy in the form of the proton motif force
43
can oxidative phosphorylation occur in the absence of oxygen?
YES bacteria may use other oxidized chemical compounds (eg. nitrate) as the terminal e- acceptor
44
how can bacteria generate energy in the without O2?
oxidative phosphorylation fermentation (substrate level phosphorylation)
45
what other carbon sources can bacteria break down?
aromatic hydrocarbons (ex. benzene) can be used to clean up polluants (ex. oil spills) bacteria convert these substrates to pyruvate and acetylaldehyde, which produces NADH --> produces ATP in the ETC
46
how can amino acids, fatty acids, and carbohydrates be synthesized?
from intermediates from glycolysis and the TCA cycle
47
what is photosynthesis?
uses light as an energy source to drive the ETC chain to produce ATP (via proton motif force) and/or reduction of NAD+ or NADP+ to NADH or NADPH
48
what are the sources of electrons to reduce the cofactors in photosynthesis?
water --> converts to O2 when it donates electrons to the ETC (aka oxygenic photosynthesis), used by cyanobacteria and chloroplasts of plants UNFAVOURABLE PROCESS anaerobic photosystems --> do not result in the formation of oxygen FAVOURABLE PROCESS
49
what are the photosystems in photsynthesis?
anaerobic photosystem I --> uses hydrogen sulfide, H2(g), or Fe2+ as electron donors in the ETC, found in green sulfur bacteria and filamentous green bacteria anaerobic photosystem II --> electrons from chlorophyll is excited by light and passed through carriers in the ETC leading to the proton motif force. electrons eventually get passed back to the chlorophyll molecule. no reduction of NAD+ or NADP+ occurs.
50
is there life deep on the ocean floor?
yes (ex. giant tube worm, gets energy from symbiotic chemolithotrophs in their bodies)
51
describe chemolithotrophy symbiosis in the giant tube worm
use HS- as e- donor O2 is the e- acceptor in the ETC energy in ETC can fix carbon, providing carbon for themselves and the tube worm red plume of tube worm takes up S- and O2 which is transported to the trophosome where chemolithotrophs live they are red because of hemoglobin
52
how do vescomyid clams draw in nutrients
O2 from distal end of shell S- from bright red foot symbiotic relationship with bacteria
53
where can chemolithotrophs be found?
the deep sea acid mine drainage (environmental concern)
54
what is the electron donor and acceptor for thiobacillus ferroxidans?
Fe II = donor O2 = acceptor can also oxidize sulfide to sulfuric acid
55
describe chemolithotrophs in the aquarium (nitrification)
proteins --> fish --> NH3 --> nitrite (NO2) (by nitrosomonas) --> nitrate (NO3-) (by nitrobacter) ammonia is donor, O2 is acceptor nitrite is less toxic than ammonia (need to prevent accumulation) many use NO2
56
how can chemolithotrophs reduce NADP+ to NADPH?
use reverse electron flow in the ETC energy requiring process, uses proton motif force can be used to form organic carbon (CO2 fixation) why life can exist on Jupiter's moons
57
in aerobic respiration, what is the initial electron donor and final electron acceptor?
D: NADH --> NAD+, FADH2 --> FAD2+ A: O2 --> H2o
58
in anaerobic respiration, what is the initial electron donor and final electron acceptor?
D: NADH --> NAD+, FADH2 --> FAD2+ A: No3- --> NO2-
59
in oxygenic photosynthesis, what is the initial electron donor and final electron acceptor?
D: H2O --> O2 A: NADP+ --> NADPH
60
in anaerobic photosystem I, what is the initial electron donor and final electron acceptor?
D: H2S --> S+, H2 --> H A: NADP+ --> NADPH
61
in anaerobic photosystem II, what is the initial electron donor and final electron acceptor?
D: chlorophyll A: chlorophyll
62
in chemolithotrophy,what is the initial electron donor and final electron acceptor?
D: Fe2+ --> Fe3+, H2S --> S + 2H+ A: O2 --> H2O

MICR 2430 (5 decks)

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