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Biochemistry > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

Where does the TCA connect to gluconeogenesis and glycolysis?

A

Gluconeogenesis- via oxaloacetate
Glycolysis- pyruvate

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2
Q

What do dehydrogenases do?

A

Convert NAD to NADH, except succinate dehydrogenase it converts FAD to FADH2

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3
Q

What are the products of the TCA cycle?

A

1 ATP
3 NADH
1 FADH_2
2 CO_2

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3
Q

What is the mnemonic for TCA Cycle?

A

Can I Keep Selling Seashells for Money Officer?
Citrate, Isocitrate, a-Ketoglutarate, Succinyl COA, Succinate, Fumarate, Malate, Oxalacetate

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4
Q

What is the rate limiting step of TCA? Why?

A

Isocitrate dehydrogenase, loss of CO_2 drives rxn forward, low delta G

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5
Q

What happens when TCA intermediate concentrations are low and energy is high

A

Glycolytic intermediates can be converted for use

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6
Q

What are the activators of the TCA cycle?

A

ADP/AMP, Ca2+

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7
Q

What are the inhibitors?

A

ATP, too much product of a step

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8
Q

Oxidation of what forms the most energy than any form of carbon?

A

fatty acids

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9
Q

Function of fat?

A

main energy source of energy for liver, heart, and resting skeletal muscle

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10
Q

What are fatty acids initially present as?

A

Triacylglycerols

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11
Q

How are fatty acids released? Location from and to?

A

B-oxidation, cytosol to mitochondria

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12
Q

4 Steps of Fatty acid activation?

A
  1. fatty acid couples to COA
  2. Carnitine acyl transferase 1 catalyzes transesterification rxn to form fatty acyl carnitine
  3. acyl carnitine cotransporter allows for passive transport of fatty acyl carnitine
  4. Carnitine acyl transferase 2 transfers fatty acid group from carnitine back to coA for regeneration
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13
Q

What are the stages of catabolism?

A
  1. Acetyl-COA production
  2. Acetyl-COA oxidation
  3. Electron transfer oxidative phosphorylation
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14
Q

What does the production stage involve?

A

Glucose to Pyruvate to Acetyl-COA

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15
Q

What does the oxidation stage involve?

A

TCA Cycle

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16
Q

Describe the conversion of oxaloacetate and acetyl COA to Citrate

A

Oxaloacetate comes from gluconeogenesis, Citrate Synthesase and water push rxn, very delta neg so very favorable

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17
Q

Citrate to Isocitrate

A

Water shifts conformation of H and OH bond

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18
Q

Isocitrate to alpha Ketoglutarate

A

Isocitrate dehydrogenase, Isocitrate oxidized by NADP, MG2+ coordinate, carboxyl removal to CO_2

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19
Q

Alpha Ketoglutarate to Succinyl COA

A

A-Keto dehydrogenase complex, removal of CO_2 and addition of -S-COA

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20
Q

Succinyl COA Synthesase Rxn (Succinate)

A

-S-COA COA is replaced with P group, P removed and added to His, P then moves to GTP

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21
Q

Succinate to Fumarate

A

Succinate dehydrogenase, removal of two H+ and production of FADH_2, leads to fumarate

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22
Q

Fumarate to Malate

A

Hydration of Fumarate

23
Q

Malate to Oxaloacetate

A

Double bond of C, two H+ leave

24
Q

What are the products of TCA Cycle?

A

1FADH_2
3 NADH
1 ATP

25
Q

TCA intermediates low but energy high?

A

Glycolytic intermediates converted for TCA

25
Q

What does it mean that the TCA cycle is amphibolic?

A

Not just cyclical involved in catabolic and anabolic rxns

26
Q

When energy is high?

A

TCA intermediates used in biosynthesis

27
Q

Features of fats

A

pack tightly
main source of energy for heart, liver, skeletal muscle
stored in adipose tissue
source of metabolic water

27
Q

What is required to bypass pyruvate kinase?

A

PEP and pyruvate carboxylase

28
Q

General activators of TCA Cycle?

A

ADP, Ca2+

29
Q

What is the immediate fate of fatty acids?

A

Bile salts breakdown fats, Mixed Micelles, Lipase degrade triacylglycerol, mixed with cholesterol/apolipoproteins into chylomicrons to lymph to bloodstream to tissues to lipase converts triacyclglycerols into fatty acids (either used as fuel or storage)

29
Q

General inhibitors of TCA cycle?

A

ATP, NADH, precursors

29
Q

Fat is very high in energy

A

T

30
Q

What acts as an open gate for triacyclglycerols?

A

Perilipin

31
Q

How are fatty acids activated and transported in the mitochondria?

A
  1. Fatty acids coupled to COA
  2. Transesterification to carnitine (Cotransporters allow for passive transport)
  3. CPT2 transesterifies fatty acyl carnitine back to COA (separates carnitine and fatty acyl COA)
32
Q

Is B oxidation efficient?

A

Yes at 60%

33
Q

Odd chain versus straight chain fatty acids?

A

Odd chain utilizes B12 and methomalonyl COA

34
Q

How does fatty acid synthesis work?

A

High glucose leads to activation of insulin to fatty acid formation

35
Q

MalonylCOA inhibits what?

A

Oxidation

36
Q

During starvation, acetyl COA can be converted to what?

A

Ketone bodies

37
Q

What are ketone bodies? Where are they formed?

A

Alternative source of energy for liver, heart, skeletal muscle, mitochondria

38
Q

Ketone bodies can be converted back to COA. Why?

A

soluble, COA is often limiting, formation of ketone bodies produce COA

39
Q

An increase in gluconeogenesis leads to depletion of oxaloacetate which slows TCA, leads to buildup of acetyl COA which then is converted to ketone bodies

A

________________

39
Q

What happens in a long fasting period?

A

Production of glucogenic acids into liver
Kidney receives urea, TCA intermediate oxaloacetate shifts to gluconeogenesis, leads to buildup of acetyl COA which increases production of ketone bodies
fatty acids come in from adipose tissue in liver which is then oxidized for fuel which produces acetyl coa

40
Q

An increase in gluconeogenesis decreases or increases TCA? Ketone formation?

A

Decreases TCA, Increases ketone body formation, can lead to ketoacidosis

41
Q

In the well fed state what does insulin signal?

A

glucose to enter cells
fats to convert to fatty acids in muscle
fats converted to triacylglycerol in liver and adipose tissue
amino acids to go to liver to produce proteins, urea and a-keto acids

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47
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48
Q
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Biochemistry (8 decks)

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