Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochem 2 > Lectures 17-18: Regulation of TCA + Ox. phos. > Flashcards

Lectures 17-18: Regulation of TCA + Ox. phos. Flashcards

1
Q

5 pathways of carbohydrates from diet

A
  • glycolysis
  • gluconeogenesis
  • glycogenesis
  • glycogenolysis
  • pentose phosphate pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

4 pathways of fats from diet

A
  • b-oxidation
  • FA synthesis
  • TG synthesis
  • Cholesterol synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

5 pathways of proteins from diet + 1 extra

A
  • transamination
  • urea cycle
  • aa catabolism
  • aa synthesis
  • synthesis of aa derivatives
    + nucleic acid synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is cellular respiration?
- 3 stages

A
  • process by which pyruvate produced by glycolysis is further oxidized to H2O and CO2 (cells consume O2 and produce CO2)
    1. acetyl CoA production/oxidation of fuels to acetyl-CoA
    2. acetyl CoA oxidation/oxidation of acetyl groups to Co2 in the citric acid cycle
    3. electron transfer chain and oxidative phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

generally:
- stage 1 of cellular respiration –> 3 things into what? + generates (3)
- stage 2: 1 thing into 2 things + generates (3)
- stage 3: 2 things into 1 thing + generates what?

A
  1. aa, fatty acids and glucose –> acetyl-coA
    + generates ATP, NADH and FADH2
  2. acetyl-coa into NADH and FADH2 through citric acid cycle
    + generates NADH, FADH2 and 1 GTP/ATP
  3. NADH and FADH2 into ATP through respiratory/electron transfer chain
    + generates vast majority of ATP from catabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

where does each stage of cellular respiration happen?

A
  • glycolysis –> cytoplasm
  • TCA cycle –> mitochondrial matrix
  • oxidative phosphorylation –>inner mitochondrial membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

3 sources of acetyl-coa?

A
  1. b oxidation of fat
  2. amino acids (leucine, thronine, etc.)
  3. glycolysis yields pyruvate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

pyruvate is the intermediate that links what 2?

A
  • 2 central catabolic pathways
  • glycolysis and TCA cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

citric acid cycle is a hub of metabolism: with ________ pathways leading in and ________ pathways leading out

A
  • catabolic leading in
  • anabolic leading out
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

3 fates of pyruvate from glycolysis?

A
  1. enters mitochondria to be oxidized by citric acid cycle to generate energy
  2. after its conversion to acetyl-CoA, may be used as starting material for synthesis of FA and sterols
  3. precursor for synthesis of amino acids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

pyruvate to acetyl-coA is what kind of reaction?
- reversible or irreversible?
- explain what happens
- what is generated?
- transfer of e- from _______ to _______ generates __-__ ATP

A
  • oxidative decarboxylation
  • irreversible
  • carboxyl group is removed from pyruvate, forming CO2 and 2 remaining carbons becomes acetyl group of acetyl-CoA
  • NADH generated –> enters respiratory chain as e- donor
  • NADH to oxygen generates 2-5 ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what enzyme complex catalyzes pyruvate to acetyl-coa?
- which 5 cofactors are needed? which one not derived from vitamins?

A
  • pyruvate dehydrogenase complex (E1 + E2 + E3)
  • CoA-SH, NAD+, lipoate, TPP, FAD
  • lipate not derived from vitamins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

pyruvate dehydrogenase (PDH) complex:
- cluster of multiple copies of what?
- describe E1, E2 and E3 –> name + cofactors

A
  • multiple copies of 3 enzymes (60 copies in bovine PDC)
  • E1 = pyruvate dehydrogenase –> bound cofactor TPP
  • E2 = dihydrolipoyl transacetylase –> covalently bound lipoyl group of lipoate
  • E3 = dihydrolipoyl dehydrogenase –> cofactors FAD and NAD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

pyruvate to acetyl-coa
- do intermediates leave the enzyme surface?
- what is that called?
- which cofactors remain bound to their enzyme?

A
  • no! never leave enzyme surface
  • substrate channeling
  • thiamine pyrophosphate (TPP), lipoate and FAD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

which steps of pyruvate to acetyl-coa catalyzed by which enzyme?

A

E1 –> step 1 and 2:
1. pyruvate + TPP –> release CO2
2. hydroxyethyl TPP tnrasfers 2e- to acyl lipoyllysine
E2 –> step 3:
3. acyl lipoylysine reduced + CoA-SH replaces SH group to form acetyl-CoA, releasing reduced lipoyllysine
E3 –> steps 4 and 5
4. FAD to FADH2 (reduced)
5. FADH2 transfers e- to NAD+ to form NADH + H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

citric acid cycle:
- how many intermediates?
- how many enzymes/steps?
- 5 general steps

A
  • 9 intermediates
  • 8 enzymes/steps
    1. acetyl-coA donates 2C to oxaloacetate (4C) forming citrate (6C)
    2. citrate transformed to isocitrate (6C)
    3. isocitrate dehydrogenated with loss of Co2 to form a-ketoglutarate (5C)
    4. a-ketoglutarate loses CO2 and yields 4C succinate
    5. succinate converted in 3 steps into 4C oxaloacetate –> ready for another cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

4 net by-products of citric acid cycle

A
  • 2 CO2 (isocitrate to a-ketoglutarate + a ketoglutarate to succinyl coA)
  • 3 NADH (same reactions that produce CO2 + malate to oxaloacetate)
  • 1 FADH2 (succinate to fumarate)
  • 1 ATP/GTP (succinyl-CoA to succinate)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

do carbons of acetyl-coa contribute to CO2 production?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

TCA cycle can serve both ________ and ________ pathways –> is __________

A
  • catabolic and anabolic
  • is amphibolic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

reactions that replenish intermediates are called what?
- 4 examples

A
  • anaplerotic
    1. pyruvate + HCO3 + ATP –> oxaloacetate (through pyruvate carboxylase)
    2. phosphoenolpyruvate + CO2 + GDP –> oxaloacetate + GTP (PEP carboxykinase)
    3. phosphoenolpyruvate + HCO3 –> oxaloacetate (PEP carboxylase)
    4. pyruvate + HCO3- + NADPH –> malate + NADP+ (malic enzyme)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

regulation of TCA cycle:
- enzymes of which reactions are regulated?
- cycle is activated by what?
- cycle is inhibited by what?
- PDH is phorphorylated on which enzyme = __________
- what does succinyl-CoA inhibit?
- what activates TCA cycle?

A
  • of irreversible reactions
  • substrate (acetyl-CoA)
  • inhibited by product accumulation
  • on E1 enzyme = inactivation of complex
  • succinyl-CoA inhibits citrate synthase (acetyl-Coa –> citrate) and a-ketoglutarate dehydrogenase complex (a-ketoglutarate –> succinyl-coa) to regulate a-ketoglutarate for aa metabolism
  • Ca2+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what activates vs inhibits pyruvate dehydrogenase complex? (catalyzes what reactions)

A
  • pyruvate to aceyl-coa
  • inhibits: ATP, Acetyl-CoA, NADH, Fatty acids
    activates: AMP, CoA, NAD+, Ca2+
23
Q

what activates vs inhibits citrate synthase? (catalyzes what reactions)

A
  • acetyl-coa to citrate
  • inhibits: NADH, succinyl-CoA, citrate, ATP
  • activates: ADP
24
Q

what activates vs inhibits isocitrate dehydrogenase? (catalyzes what reactions)

A
  • isocitrate –> a-ketoglutarate
  • inhibits: ATP
  • activates: Ca2+ + ADP
25
Q

what activates vs inhibits a-ketoglutarate dehydrogenase complex? (catalyzes what reactions)

A
  • a-ketoglutarate –> succinyl-CoA
  • inhibits: succinyl-CoA, NADH
  • activates: Ca2+
26
Q

carbs, lipids and aa are _________ fuels

A

reduced

27
Q

electrons are transferred to cofactors ____ OR ____

A

NAD or FAD

28
Q

oxidative phosphorylation occurs in ________ and involves huge ________ ________ embedded in _______ ________ ________

A
  • mitochondria
  • protein complexes
  • embedded in inner mitochondrial membrane (contains components of respiratory chain and ATP synthase)
29
Q

energy from _____ and _______ is used for ATP synthesis
- these 2 molecules are _______ ______ ________

A
  • NADH and FADH2
  • reduced electron carriers
30
Q

oxidative phosphorylation involves oxidation/reduction of ____ to _____ using ______ donated from ______ and ________

A
  • reduction of O2 to H2O using electrons donated from NADH and FADH2
31
Q

3 membrane-bound electron carriers?
1. __________ –> + 1 e- VS + 2e- + transfers e- from where to where?
2. ________ –> 3 types
3. ______ _______ proteins –> contains how many of each atoms?

A
  1. ubiquinone/coenzyme Q (fully oxidized) = mobile electron carrier
    - QH –> semiquinone radical
    - QH2 –> ubiquinol (fully reduced)
    - transfers e- from complex I/II to complex iv
  2. cytochrome –> type a, b or c
  3. iron sulfur proteins –> 1, 2 or 4 iron associated with sulfur
    2.
32
Q

overview of oxidative phosphorylation:
- complex I and II
- complex III
- complex iv

A

1 and 2: catalyze electron transfer to ubiquinone from 2 different electron donors: NADH (complex I) and succinate/FADH (complex II)
3. carries electrons form reduced ubiquinone to cytochrome c
4. completes sequence by transferring electrons from cytochrome c to O2

33
Q

5 sources of NADH

A
  1. b-oxidation (1 NADH per cycle)
  2. glycolysis (2 NADH)
  3. pyruvate to acetyl-CoA (1 NADH)
  4. TCA (3 NADH)
  5. amino acid oxidation to pyruvate, acetyl-coA, fumarate, a-ketoglutarate, succinyl-CoA
34
Q

4 paths of electrons to ubiquinone

A
  1. (complex I) NADH –> flavin mononucleotide (FMN) –> iron-sulfur protein (Fe-S) –> Q –> QH2
  2. (complex II) Succinate –> Flavin adinosine diphosphate (FAD) –> Fe-S –> QH2
  3. (glycerol 3-phosphate dehydrogenase) glycerol 3-phosphate (cytosolic) –> FAD –> QH2
  4. Fatty-acyl CoA –> FAD (of acyl-coA dehydrogenase) –> FAD (ETF) –> Fe-S, FAD (ETF:Q oxidoreductase) –> QH2
35
Q

complex I:
- size? shape?
- ____ subunits encoded by (2) types of genes
- name?
- 2 processes

A
  • largest of 4 complexes. L shaped (1 arm embedded in intermembrane + one arm inside matrix)
  • 45 subunits encoded by nuclear and mitochondrial genes
  • NADH-quinone oxidoreductase
    1. transfer of 2 e- from NADH to ubiquinone (through FMN, Fe-S and Q)
    2. pumping 4 H+ from matrix (negative) to intermembrane space (+)
36
Q

net equation of complex I

A

NADH + Q + 5 H+(N) –> NAD+ + QH2 + 4 H+ (P)

37
Q

which side of membrane is negative vs positive?

A
  • intermembrane space = positive
  • matrix = negative
38
Q

complex II:
- name?
- 4 subunits –> roles? + binding site for what?
- 2 roles?
- pumps H+?

A
  • succinate dehydrogenase
  • a and b –> extend to matrix –> have iron-S proteins –> bound to FAD (co-factor) + binding site for succinate
  • c and d have heme –> binding site for ubiquinone
    ROLES:
    1. converts succinate to fumarate in TCA cycle
    2. capture and donate e- in electron transport chain (AKA reduces ubiquinone (Q) to QH2 (Ubiquinol)
  • NO proton pumping
39
Q

Complex III:
- 3 functional units?
- 2 pathways/steps/roles?

A
  • cytochrome b = a dimer: cavern where ubiquinone can move from matrix to intermembrane space
  • cytochorme C1
  • iron-sulfur center
    1. transfers electron from ubiquinol to cytochrome C –> QH2 oxidized –> 1 e- passes through Fe-S –> heme C1 –> cyt C AND QH2 –> 1 e- to heme b –> Q –> becomes °Q- –> becomes QH2 (ish)
    2. releases 4 protons to intermembrane space –> 2 QH2 each release 2 protons
40
Q

reactions of stage 1 and 2 + net equation of complex III

A

stage 1:
QH2 + Q + cyt c (oxidized) –> Q + °Q- + 2 H+ (P) + cyt c (reduced)
stage 2:
QH2 + °Q- + 2H+ (N) + cyt c (oxidized) –> Q + 2H+ (P) + QH2 + cyt c (reduced)
net equation:
QH2 + 2 cyt c (oxidized) + 2 H+ (N) –> Q + 4 H+ (P) + 2 cyt c (reduced)

41
Q

complex IV:
- name?
- 3 subunits
- 2 roles?

A
  • cytochrome oxidase
  • Subunit 1 = 2 hemes + 1 copper ion
  • subunit 2: copper ion
  • subunit 3: heme a1
    1. transfer electron from cytochrome c to O2 (4 e- bc 4 cyt c) (cyt c –> copper ion –> heme a –> heme a3 –> copper ion B –> O2 –> forming H2O in matrix
    2. transports 2 protons to outside per electron pair (4 H+ in total) (uses energy from O2 to H2O)
42
Q

what is a respirasome?
2 examples

A

functional combinations of many complexes/electron carriers
1. complex 1, 3 and 4
2. complex 2, 3 and 4

43
Q

net equation for respirasome of complex 1, 3 and 4
What + _____ H+ + 0.5 O2 —> ?

A

1 NADH + 11 H+ (N) + 1/2 O2 –> NAD+ + 10 H+(P) + H2O

44
Q

net equation for respirasome of complex 2, 3 and 4

A

1 FADH2 + 6 H+ (N) + 1/2 O2 –> FAD + 6 H+ (P) + H2O

45
Q

does NADH or FADH2 produce more electrochemical gradient?

A

NADH
10 H+ vs 6 H+

46
Q

proton motive force comes from (2)?
- role?

A
  1. chemical potential (delta pH) –> inside alkaline
  2. electrical potential –> inside negative
    - drive protons back into matrix which provide E to synthesize ATP
47
Q

electrochemical proton gradient created by (3)

A
  1. active transport of protons (complex 1 and 4)
  2. release of protons into intermembrane space –> oxidation of QH2 (complex 3)
  3. chemical removal of protons from the matrix –. reduction of Q (complex 1, 2, 3) and Oxygen (complex 4)
48
Q

is the inner mitochondrial membrane permeable to H+?
- How can H+ reenter matrix?

A
  • no! impermeable
  • leave matrix through complexes
  • reenter matrix through Fo (pump/channel)
49
Q

is the inner mitochondrial membrane permeable to NADH?
- how does NADH travel to matrix/intermembrane space? (2 ways depending on where?)

A

impermeable!
- in most cells –> malate aspartate shuttle (NAD+ on intermembrane space vs NADH on matrix side)
- in skeletal muscle and brain –> glycerol 3-phosphate shuttle

50
Q

what is the ATP yield of glucose (glycolysis, pyruvate oxidation, TCA)?

A

glycolysis: 5 (or 7)
pyruvate oxidation: 5
TCA cycle: 20
TOTAL: 30 or 32

51
Q

how many ATP do NADH and FADH2 yield?

A
  • NADH: 2.5 ATP
  • FADH2: 1.5 ATP
52
Q

what is the ATP yield of palmitate (b-oxidation, TCA cycle)?

A

beta oxidation: 28
TCA cycle: 80
TOTAL: 108 ATP!

53
Q

how is oxidative phosphorylation regulated?

A
  • mass action ratio [ATP]/([ADP][Pi]) –> increase ATP/NADH or decrease ADP/AMP/NAD –> low rate of everything (glycolysis, TCA, ox phos)
54
Q

ATP is synthesized as fast as ?

A

as fast as it is utilized!

Biochem 2 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions