Brainscape's Knowledge GenomeTM

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


See full index

MCAT BIochem > Kreb's Cycle and Oxidative Phosphorylation > Flashcards

Kreb's Cycle and Oxidative Phosphorylation Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards
1
Q

Where does the citric acid cycle take place?

A

Mitochondria matrix

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

What is the main function of the citric acid cycle?

A

Oxidize Acetyl-CoA to CO2 and H20 and produce NADH and FADH2 energy molecules

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

What product of glycolysis enters the mitochondria?

A

Pyruvate via active transport

Oxidized and decarboxylated

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

Where is pyruvate dehydrogenase complex?

A

In the mitochondrial matrix

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

How many carbons are in pyruvate?

A

3

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

How many carbons are in acetyl-CoA

A

2

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

Is conversion from pyruvate to acetyl-CoA reversible?

A

No

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

Is pyruvate dehydrogenase reaction spontanteous?

A

Yes Delta G=-33.4 kJ/mol

Exergonic

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

What inhibits pyruvate dehydrogenase?

A

Acetyl-CoA accumulation and NADH

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

What are the enzymes of pyruvate dehydrogenase complex?

A 
Pyruvate dehydrogenase (PDH)
DIhydrolipoyl transacetylase
Dihydrolipoyl dehydrogenase 
^Conversion
Pyruvate dehydrogenase kinase
Pyruvate dehydrogenase phosphatase
^Regulate PDH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What kind of group is CoA

A

Thiol

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

What kind of bond does pyruvate dehydrogenase create?

A

Thioester

High energy properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pyruvate dehydrogenase (PDH)

A

Pyruvate is oxidized to yield CO2

Two carbon remaining binds to Thiamine pyrophosphate (Vitamin B1) Mg2+ is required

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

Dihydrolipoyl transacetylase

A

Two carbon molecule transferred to lipoic acid from TPP
Lipoic acid has a disulfide group acts as an oxidizing agent and forms the acetyl group
Transfers acetyl group to new thiolester link

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

Dihydorlipoyl dehydrogenase

A

FAD reoxidizes lipoic acid and is oxidized to FADH2

NAD+ used to reoxidize FAD+

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

Fatty acid oxidation (B oxidation) and Acetyl CoA

A

Fatty acyl-CoA is transported to intermembrane space of mitochondria
Fatty acyl is transferred to carnitine via tranesterification (can’t cross inner membrane)
Crosses inner membrane
Converts back to fatty acyl-CoA
B-oxidation removes 2 C from the carboxyl end

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

Amino acid catabolism and Acetyl CoA

A

Transamination to remove amino group

Form ketone bodies also

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

Ketones and Acetyl CoA

A

Ketones can be used to make acetyl-CoA

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

Alcohol and Acetyl CoA

A

Alcohol dehygenase and acetaldehyde dehydrogenase convert alcohol to acetyl-CoA
Although it also causes NADH buildup that inhibits Krebs cycle

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

Why is the Kreb’s cycle aerobic only?

A

NADH FADH2 will build up if O2 is not available to oxidize it in the ETC

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

Step 1- Citrate Formation

A

Citrate Synthase

Acetyl-CoA and OAA to Citrate

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

Step 2- Citrate Isomerized to Isocitrate

A

Aconitase (requires Fe2+) - an Isomerase

Citrate to Isocitrate

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

Step 3- a-Ketoglutarate and CO2 formation

A

Isocitrate dehydrogenase

Isocitrate to Oxalosuccinate to a-ketoglutarate and CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What steps of the citric acid cycle are rate limiting?

A

Isocitrate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where is the first NADH produced during the citric acid cycle?

A

Isocitrate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

A dehydrogenase is what type of enzyme?

A

Oxidoreductase

Oxidation-reduction reactions

27
Q

Step 4- Succinyl-CoA and CO2 formation

A

a-ketoglutarate dehydrogenase

a-ketoglutarate and CoA to CO2, Succinyl-CoA and NADH

28
Q

Step 5- Succinate Formation

A

Succinyl-CoA synthetase (creates new bonds with energy input)
Succinyl-CoA to Succinate and GTP

29
Q

Where does the energy come from to create GTP?

A

Thioester hydrolysis of Succinyl-CoA

30
Q

Step 6- Fumarate Formation

A

Succinate dehyrdrogenase

Succinate to Fumarate and FADH2

31
Q

Where does fumarate formation occur?

A

In the inner membrane (FADH2 is a integral protein)

32
Q

Step 7- Malate Formation

A

Fumarase

Fumarate to malate

33
Q

Step 8-Oxaloacetate formation

A

Malate dehydrogenase

Malate to OAA and NADH

34
Q

Where is NADH made during Citric acid cycle?

A

Pyruvate dehydrogenase
Isocitrate dehydrogenase
a-ketoglutarate dehydrogenase
Malate dehydrogenase

35
Q

Mnemonic for Citric Acid Cycle Substrates

A

Please, Can I Keep Selling Seashells for Money, Officer?

36
Q

When in CO2 formed?

A

isocitrate dehdyrogenase

a-ketoglutarate dehydrogenase

37
Q

How much energy does glycolysis yield?

A

2 ATP and 2 NADH ( 7 ATP)

38
Q

How much energy does citric acid cycle yield

A

4 NADH
1 FADH2
1 GTP
=12.5 ATP per pyruvate= 25 ATP per glucose

39
Q

What enzymes regulate pyruvate dehydrogenase?

A

Pyruvate dehydrogenase kinase
Pyruvate dehydrogenase phosphatase

Phosphorylation inhibits pyruvate dehydrogenase
Also Acetyl-CoA negatively feeds back

40
Q

Control of citrate synthase

A

ATP and NADH allosteric inhibitors
Also Citrate and succinyl-CoA
Alosterically

41
Q

Control of Isocitrate dehydrogenase

A

Inhibited by ATP and NADH allosterically

42
Q

Control of a-ketoglutarate dehydrogenase

A

Inhibited by succinyl-CoA
ATP
NADH

43
Q

What stimulates a-ketoglutarate dehydrogenase?

A

ADP

Calcium

44
Q

What drives the production of ATP?

A

Proton gradient

45
Q

Where is the electron transport chain?

A

Inner mitochondrial matrix

46
Q

Where are electrons given at the end of the ETC?

A

Water

47
Q

How are protons moved?

A

Mitochondrial matrix into intermembrane space

Lower pH in inner membrane space

48
Q

Molecule with higher reduction potential will be?

A

Reduced, other will oxidized

49
Q

Complex I (NADH- CoQ Oxidoreductase)

A

Electrons from 2 NADH transferred to Flavin mononucleotide (FMN)
Iron-sulfur subunit takes electrons
Donates them to Coenzyme Q/ Ubiquinone
4 Hydrogens pumped into inner membrane space

50
Q

Complex II (Succinate-CoQ Oxidoreductase)

A

Electrons from succinate to FAD
FADH2 donates electrons to iron-sulfur protein to Coenzyme Q
No hydrogens pass through

51
Q

Complex III (CoQH2 -cytochrome c oxidoreductase)

A

Electrons from Coenzyme Q to 2 Cytochrome c molecules

Contributes protons via Q cycle

52
Q

Cytochrome

A

Proteins with heme groups in which iron is reduced to Fe2+ and reoxidized to Fe3+

53
Q

Q cycle

A

In complex III
2 electrons are shuttled from a molecule of ubiquinol to ubiquinone
Displaces 4 H+ into the intermembrane space

54
Q

Complex IV (cytochrome c oxidase)

A

Transfer of electrons from cytochrome c to oxygen
Cytochrome oxidase made of ctochrome a, cytochrome a3 and Cu2+ ions
4 cytochrome c oxidized
2H+ across ETC
2H+ given to water

55
Q

Eletro-chemical gradient

A

pH decrease in intermembrane space

Voltage difference between intermembrane space and matrix increases

56
Q

Why is ATP produced in a range?

A

Variable efficiency of NADH from glycolysis cannot directly cross the mitochondrial matrix and must be shuttled in
Either shuttle will yield 1.5 or 2.4 ATP

57
Q

Glycerol 3-phosphate shuttle

A

In cytosol
Glycerol 3-phosphate dehydrogenase forms G3P from DHAP
Transfers electrons to FAD
FADH2 gives electrons to Complex II= 1.5 ATP

58
Q

Malate-aspartate shuttle

A

Malate dehydrogenase
OAA to malate can pass through the mitochondrial membrane
Gives electrons from NADH and reconverted back to NADH in cytosol–>give electrons to Complex I
Left over OAA converted to aspartate and back into the cytosol

59
Q

Which way does ATP synthase protrude into?

A

Matrix

60
Q

Fo portion

A

Spans membrane

An ion channel that protons move through along their gradient into the matrix

61
Q

Chemiosmotic coupling

A

Allows chemical energy of gradient to be harnessed to phosphorylate ADP

62
Q

F1 portion

A

Utilizes energy released from this electrochemical gradient to phosphorylate ADP to ATP

63
Q

Conformational coupling

A

Suggest indirect relationship between ATP and proton gradient

64
Q

Oxidative Phosphorylation is highly?

A

Exergonic

MCAT BIochem (8 decks)

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