Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochem BLOCK 2 > TCA (Krebs Cycle) > Flashcards

TCA (Krebs Cycle) Flashcards

1
Q

TCA cycle names

A

krebs, TCA, citric acid

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

final pathway of TCA

A

catabolism of carbs, AA, and FA converge and their carbon skeletons being converted to CO2

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

catabolic pathway of TCA

A

breakdown of some AA provides certain TCA cycle intermediates

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

anabolic pathways of TCA

A

-some TCA intermediates feed into biosynthetic pathways, such as the synthesis of certain amino acids

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

what provides the most energy?

A

terminal oxidation of all biomolecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what carries the energy from the terminal oxidation of all biomolecules for the production of ATP in the ETC

A

NADH and FADH2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

oxidative phosphorylation in TCA

A

ETC couple the oxidation of the reduced carriers produced by the TCA cylce with the production of ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is the TCA cycle located?

A

mitochondrial matric, in close proximity to the ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

linear metabolic pathway

A

starts with 1 metabolite and ends up with a different one (glycolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

cycle metabolic pathway

A

starts with a certain metabolite that undergoes multiple steps forming different intermediates but in the end the same initial metabolite is regenerated. There is no net loss or gain of intermediates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

reactions required prior the TCA cycle

A

oxidative decarboxylation of pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

oxidative decarboxylation of pyruvate

A
  1. transported into the mitochondria
  2. converted into acetyl CoA by pyruvate dehydrogenase complex (PDH)
  3. during the reactions 1 C atom is released as CO2 and NADH is produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pyruvate dehydrogenase complex (PDH)

A
  • protein aggregate of 3 separate enzymes

- 5 different coenzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 3 different enzymes that make up PDH?

A

E1, E2, E3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the 5 coenzymes associated with PDH

A
  • thiamine triphosphate, TPP
  • lipoamide
  • CoA
  • FAD
  • NAD+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

thiamine pyrophosphate

A
  • PDH coenzyme

- from thiamine, vit B1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

lipoamide

A
  • PDH coenzyme

- synthesized in human cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

CoA

A
  • PDH coenzyme

- pantothenic acid, Vit B5

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

FAD

A
  • PDH coenzyme

- from riboflavin, vit B2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

NAD+

A
  • PDH coenzyme

- from nicotinamide, vit B3/niacin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

regulation of PDH

A
  • phosphorlyation deactivates

- dephosphorylation activates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

PDH kinase and phophatase can be allosterically activated or inhibited by…

A
  • substrate activation

- product inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Active PDH

A
  • pyruvate
  • NAD+
  • ADP
  • Ca2+
  • CoA
24
Q

deactive PDH

A
  • Acetyl CoA
  • NADH
  • ATP
25
1. synthesis of citrate from acetyl CoA and oxaloacetate
- condensation - form citrate - enzyme: citrate synthase - IRREVERSIBLE
26
enzyme ofsynthesis of citrate from acetyl CoA and oxaloacetate
citrate synthase
27
citrate synthase
- enzyme for the synthesis of citrate from acetyl CoA and oxaloacetate - regulated simply by substrate activation or product inhibition
28
citrate
- precursor for FA synthesis | - inhibitor for PFK1 (feedback inhibitor)
29
2. isomerization of citrate
-enzyme: Aconitase
30
Aconitase
- enzyme for isomerization of citrate - Fe-S protein - potentially inhibited by fluoroacetate which results in citrate accumulation (suicide inhibition)
31
3. oxidative decarboxylation of isocitrate
- irreversible - rate limiting - yields 1st NADH - releases 1 CO2 - enzyme: isocitrate dehydrogenase
32
isocitrate dehydrogenase
- enzyme for oxidative decarboxylation of isocitrate - regulated allosterically - inhibitors: ATP and NADH - activators: ADP and Ca2+
33
a-ketoglutarate
alos produces from the metabolism of glutamate
34
4. oxidative decarboxylation of alpha-ketogluatarate
- irreversible - yields second NADH - releases 1 CO2 - enzyme:a-ketoglutarate dehydrogenase complex
35
a-ketoglutarate dehydrogenase complex
- multiple copies of 3 enzymes - coenzymes: TPP, lipoic acid, FAD, NAD+, CoA - inhibitors: its products - activators: Ca2+
36
Succinyl CoA
also produced from propionyl CoA derived from FA metabolism,
37
vitamin deficiencies
- a-ketoglutarate dehydrogenase and PDH both require multiple coenzymes derived from vitamins - deficiency of niacin or thiamine can cause serious central nervous system problems
38
arsenic poisoning
- a-ketoglutarate dehydrogenase complex and PDH both require lipoic acid - forms stable thiol with the -SH in lipoic acid making it unavailable - affects the brain causing neurological disturbances and death
39
5. cleavage of succinyl CoA
- cleaves high-energy thirster bonds (used to make ATP) - GDP-GTP via substrate level phosphorylation - GTP readily converted to ATP - releases CoA - enzyme: succinate thiokinase
40
6. oxidation of succinate to fumarate
- 2 H-atoms are transferred to FAD to produce FADH2 | - enzyme: succinate dehydrogenase
41
what enzyme is embedded in the inner mitochondrial membrane (complex II of ETC)?
succinate dehydrogenase
42
7. hydration of fumarate
- produces malate | - enzyme: fumarase
43
malate also produced in
- urea cycle - purine synthesis - Phe and Tyr catabolism
44
8. oxidation of malate
- + free energy change - driven toward OAA by the next highly exergonic rxn - produces final NADH - enzyme: malate dehydrogenase
45
what step produces the final NADH?
oxidation of malate
46
oxaloacetate produced also by
transamination of aspartic acid
47
what are the 3 irreversible steps?
- synthesis of citrate - oxidative decarboxylatiion of isocitrate - oxidative decarboxylation of a-ketoglutarate
48
What is the rate limiting step of TCA cycle?
oxidative decarboxylation of isocitrate
49
what are the enzymes of the irreversible steps of the TCA?
- citrate synthase - isocitrate dehydrogenase - a-ketoglutarate dehydrogenase complex
50
What intermediates get consumed or produced in TCA?
none
51
how many NADH produced in TCA?
3
52
how many FADH2 produced in TCA?
1
53
how many GTP produced in TCA?
1, by substrate level phosphorylation
54
total ATP molecules/glucose molecules in glycolysis and TCA
38 (TCA runs twice)
55
what step has substrate level phosphorylation in TCA?
cleavage of succinyl CoA | enzyme: succinate thiokinase
56
what step produces the first NADH in TCA?
oxidative decarboxylation of isocitrate, the rate limiting step
57
What step yields the second NADH in TCA?
oxidative decarboxylation og a-ketoglutarate

Biochem BLOCK 2 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions