Exam 4

Question 1

Where does the TCA connect to gluconeogenesis and glycolysis?

Answer 1

Gluconeogenesis- via oxaloacetate
Glycolysis- pyruvate

Question 2

What do dehydrogenases do?

Answer 2

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

Question 3

What are the products of the TCA cycle?

Answer 3

1 ATP
3 NADH
1 FADH_2
2 CO_2

Question 3

What is the mnemonic for TCA Cycle?

Answer 3

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

Question 4

What is the rate limiting step of TCA? Why?

Answer 4

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

Question 5

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

Answer 5

Glycolytic intermediates can be converted for use

Question 6

What are the activators of the TCA cycle?

Answer 6

ADP/AMP, Ca2+

Question 7

What are the inhibitors?

Answer 7

ATP, too much product of a step

Question 8

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

Answer 8

fatty acids

Question 9

Function of fat?

Answer 9

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

Question 10

What are fatty acids initially present as?

Answer 10

Triacylglycerols

Question 11

How are fatty acids released? Location from and to?

Answer 11

B-oxidation, cytosol to mitochondria

Question 12

4 Steps of Fatty acid activation?

Answer 12

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

Question 13

What are the stages of catabolism?

Answer 13

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

Question 14

What does the production stage involve?

Answer 14

Glucose to Pyruvate to Acetyl-COA

Question 15

What does the oxidation stage involve?

Answer 15

TCA Cycle

Question 16

Describe the conversion of oxaloacetate and acetyl COA to Citrate

Answer 16

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

Question 17

Citrate to Isocitrate

Answer 17

Water shifts conformation of H and OH bond

Question 18

Isocitrate to alpha Ketoglutarate

Answer 18

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

Question 19

Alpha Ketoglutarate to Succinyl COA

Answer 19

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

Question 20

Succinyl COA Synthesase Rxn (Succinate)

Answer 20

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

Question 21

Succinate to Fumarate

Answer 21

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

Question 22

Fumarate to Malate

Answer 22

Hydration of Fumarate

Question 23

Malate to Oxaloacetate

Answer 23

Double bond of C, two H+ leave

Question 24

What are the products of TCA Cycle?

Answer 24

1FADH_2 3 NADH 1 ATP

Question 25

TCA intermediates low but energy high?

Answer 25

Glycolytic intermediates converted for TCA

Question 25

What does it mean that the TCA cycle is amphibolic?

Answer 25

Not just cyclical involved in catabolic and anabolic rxns

Question 26

When energy is high?

Answer 26

TCA intermediates used in biosynthesis

Question 27

Features of fats

Answer 27

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

Question 27

What is required to bypass pyruvate kinase?

Answer 27

PEP and pyruvate carboxylase

Question 28

General activators of TCA Cycle?

Answer 28

ADP, Ca2+

Question 29

What is the immediate fate of fatty acids?

Answer 29

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)

Question 29

General inhibitors of TCA cycle?

Answer 29

ATP, NADH, precursors

Question 29

Fat is very high in energy

Answer 29

T

Question 30

What acts as an open gate for triacyclglycerols?

Answer 30

Perilipin

Question 31

How are fatty acids activated and transported in the mitochondria?

Answer 31

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)

Question 32

Is B oxidation efficient?

Answer 32

Yes at 60%

Question 33

Odd chain versus straight chain fatty acids?

Answer 33

Odd chain utilizes B12 and methomalonyl COA

Question 34

How does fatty acid synthesis work?

Answer 34

High glucose leads to activation of insulin to fatty acid formation

Question 35

MalonylCOA inhibits what?

Answer 35

Oxidation

Question 36

During starvation, acetyl COA can be converted to what?

Answer 36

Ketone bodies

Question 37

What are ketone bodies? Where are they formed?

Answer 37

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

Question 38

Ketone bodies can be converted back to COA. Why?

Answer 38

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

Question 39

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

Answer 39

________________

Question 39

What happens in a long fasting period?

Answer 39

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

Question 40

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

Answer 40

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

Question 41

In the well fed state what does insulin signal?

Answer 41

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