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Biochemistry > Signal Transduction, Metabolism, PDH Complex, Citric Acid Cycle > Flashcards

Signal Transduction, Metabolism, PDH Complex, Citric Acid Cycle Flashcards

1
Q

Why is epinephrine released?

A

“Fight or Flight” Stimulus

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2
Q

Why is glucagon released?

A

low glucose levels

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3
Q

Why is insulin released?

A

High glucose levels

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4
Q

What are the steps for the G-protein system?

A

Binds to activated Receptor

GDP replaced with GTP

GTP-active protein binds to GTP-activated enzyme

cellular response

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5
Q

What is a primary messenger?

A

Example: a hormone, released directly from environmental stimulus

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6
Q

What is a secondary messenger?

A

A relay molecule that responds and reacts to the primary messenger

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7
Q

What is involved with the β-adrenergic receptor and G protein?

A

Epinephrine

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8
Q

cAMP functions as a second messenger activated by…

A

adenylate cyclase

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9
Q

What does cAMP activate?

A

Protein Kinase A

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10
Q

What does DAG activate?

A

Protein Kinase C

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11
Q

What does IP3 activate?

A

Ca2+ to release from ER

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12
Q

Only active as a dimer. Once dimerized, the subunits autophosphorylate one another

A

Tyrosine kinases (like insulin)

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13
Q

How do signals get terminated?

A
  1. Deactivate the secondary messenger
  2. Deactivate the subunit responsible for synthesizing the secondary messenger
  3. Dissociate the primary messenger from the receptor
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14
Q

How does our body use free energy?

A

For movement

For molecular transport into and out of cells

For synthesis of bio-macromolecules

Note that all of these processes require ATP

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15
Q

Exergonic reaction, cell respiration, hydrolysis of ATP

A

Catabolism

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16
Q

Endergonic reaction, cell movements, active transport, synthesis of ATP

A

Anabolism

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17
Q

What is the reaction for Keq?

A

𝐾eq = [products]/[reactants]

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18
Q

What is the reaction for ∆G°′?

A

∆G°′ = −RT 𝑙n ([products]/[reactants])

R is the gas constant

T is the temperature in Kelvin

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19
Q

If energy is released, and the reaction is spontaneous, then Keq is…?

A

>1

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20
Q

If energy is added, and the reaction is not spontaneous, then Keq is…?

A

<1

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21
Q

____ is intermediate in phosphoryl transfer potential, it can easily be replenished using compounds with higher phosphoryl transfer potential

rapidly consumed and replenished

A

ATP

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22
Q

The oxidation of carbon fuels

A

catabolism

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23
Q

An electron carrier in metabolism

A

NAD+

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24
Q

Involved mainly in fatty acid synthesis

A

NADPH

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25
Q

An electron carrier in metabolism, usually lower energy

A

FAD+

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26
Q

A carrier of acyl groups

A

Co-enzyme A

27
Q

Derived from B Vitamins

A

Co-enzymes

28
Q

How are metabolic processes regulated?

A
  1. Control the amount of enzyme (kinetics)
  2. Control the catalytic activity of the enzyme (allosterism, phosphorylation, etc.)
  3. Control accessibility of substrates (membrane compartmentalization)
29
Q

What are the fates of pyruvate?

A

the fate of pyruvate can be lactic acid or ethanol (depending on organism) if cell is anaerobic or acetyl CoA if the cell is aerobic.

30
Q

What are the 3 Steps for conversion of pyruvate to acetyl CoA?

A

1) decarboxylation, 2) oxidation, 3) CoA transfer

31
Q

At what point is conversion of Pyruvate irreversible?

A

When it’s converted into acetyl CoA

32
Q

E3 complex activation

A

Inhibited by NADH; Activated by NAD+

33
Q

E2 complex activation

A

Inhibited by Acetyl CoA; Activated by CoA

34
Q

E1 complex: PDK/PDP activation

A

Inhibited by ATP; activated by ADP via phos/dephos

35
Q

What cofactor accepts the acetyl group from pyruvate?

A

Thiamine pyrophosphate (TPP)

36
Q

What cofactor transfers the acetyl group from TPP to CoA?

A

Lipoic Acid

37
Q

What are E3 cofactors?

38
Q

E2 is allosterically inhibited by

A

high acetyl-CoA

39
Q

E3 is allosterically inhibited by

40
Q

The E1 subunit of the PDC is regulated through

A

phosphorylation/dephosphorylation

41
Q

What is the overall reaction for the CAC?

A

acetyl-CoA + 3 NAD+ + FAD + ADP + Pi → 2 CO2 + 3 NADH + FADH2 + ATP

42
Q

What step in the citric acid cycle is this?

43
Q

What enzyme is used in this step of the citric acid cycle?

A

Citrate Synthase

44
Q

What step in the citric acid cycle is this?

45
Q

What enzyme is used in this step of the citric acid cycle?

A

Acconitase

46
Q

What step in the citric acid cycle is this?

47
Q

What enzyme is used in this step of the citric acid cycle?

A

isocitrate dehydrogenase

48
Q

What step in the citric acid cycle is this?

49
Q

What enzyme is used in this step of the citric acid cycle?

A

a-ketoglutarate dehydrogenase

50
Q

What step in the citric acid cycle is this?

51
Q

What enzyme is used in this step of the citric acid cycle?

A

succinyl CoA synthetase

52
Q

What step in the citric acid cycle is this?

53
Q

What enzyme is used in this step of the citric acid cycle?

A

succinate dehydrogenase

54
Q

What step in the citric acid cycle is this?

55
Q

What enzyme is used in this step of the citric acid cycle?

56
Q

What step in the citric acid cycle is this?

57
Q

What enzyme is used in this step of the citric acid cycle?

A

malate dehydrogenase

58
Q

Isocitrate Dehydrogenase activation

A

activate with ADP and NAD+/inhibit with ATP and NADH

59
Q

a-ketoglutarate dehydrogenase activation

A

activate with ADP and NAD+/inhibit with ATP and NADH and succinyl CoA

60
Q

Where in the citric acid cycle is ATP produced?

61
Q

Where in the citric acid cycle is NADH produced?

A

Steps 3, 4, & 8

62
Q

Where in the citric acid cycle is FADH2 produced?

63
Q

The primary control points within CAC are which two enzymes that catalyze oxidative decarboxylations?

A

Isocitrate dehydrogenase

α-ketoglutarate dehydrogenase

64
Q

Why isn’t the first step (ie. citrate to isocitrate) a regulatory step?

A
  • This step is readily reversible
  • Citrate is a signal molecule that can go into cytoplasm to inhibit PFK
  • Citrate also serves as source of Acetyl-CoA in fatty acid synthesis

Biochemistry (12 decks)

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