TCA Cycle

Question 1

TCA Outline

Answer 1

Bulk of ATP production in oxidative metabolism. Products enter ETC. Amphibolic (both catabolic and anabolic processes)

Question 2

Oxaloacetate in TCA Cycle

Answer 2

Used to condense Acetyl Co. A in 1st step of cycle. Is produced in last step (no net consumption). Used in glucogenesis

Question 3

Carbons in TCA cycle

Answer 3

Acetyl Co As enter a cycle and 2 CO2 leaves cycle (2 Cs enter a cycle and 2 leave). No net consumption of intermediates. Substrate of biosynthetic reactions

Question 4

Dehydrogenase Functions

Answer 4

Takes a H from a substance (eg substrates) and gives it to another (eg Fad and NAD+)

Question 5

TCA Cycle Function

Answer 5

By oxidising it’s intermediates it reduces the electron carriers (via hydrogenases) for ETC. NAD+ -> NADH and FAD -> FADH2

Question 6

Rate limiting step of TCA Cycle

Answer 6

Isocitrate dehydrogenase takes H and 2 electrons from isocitrate (oxidised) and gives them NAD+ (reduced to NADH)

Question 7

Alpha-ketoglutarate dehydrogenase Outline

Answer 7

Oxidises alpha-ketoglutarate, reduce NAD+

Question 8

Succinate Thiokinase (energy generation) Outline

Answer 8

Acts on Succinyl Co A by substrate level phosphorylation producing GTP

Question 9

Succinate Dehydrogenase Function

Answer 9

Oxidises Succinate, reducing FAD to FADH2. Is generated in electron transport chain

Question 10

Malate Dehydrogenase Outline

Answer 10

Oxidises Malate (to oxaloacetate), reducing NAD+ to NADH

Question 11

TCA Energy Production

Answer 11

3 NADH -> 3 NAD+ (9ATP), FADH2 -> FAD (2 ATP) + 1 GTP (ATP). 12 ATP = 1 Acetyl Co. A = 0.5 Glucose

Question 12

How much ATP does lactose take to form

Answer 12

3 ATP

Question 13

Why are shuttle systems necessary

Answer 13

Electron carriers don’t have pumps across membranes

Question 14

Where does TCA cycle occur

Answer 14

Mitochondrial matrix

Question 15

How much ATP is produced in anaerobic respiration (glycolysis only)

Answer 15

8

Question 16

Energy Not Used in ATP Outline

Answer 16

More energy is generated in TCA cycle then is made into ATP. Used to transport Ca^2+ and generate heat

Question 17

Role of Amino Acids in TCA

Answer 17

Act as intermediates. Reaction goes both ways as TCA cycle intermediates can also form amino acids

Question 18

Reaction of adding amino acids to glutamate

Answer 18

Forms alpha-ketoglutarate

Question 19

Excess Acetyl Co A

Answer 19

Forms fatty acids to later synthesise triglycerides and phospholipids

Question 20

Only enzyme of TCA cycle not in mitochondrial matrix

Answer 20

succinate dehydrogenase. Found in mitochondrial membrane as part of ETC

Question 21

Inner Mitochondrial Membrane Outline

Answer 21

Impermeable