Energy Production

Question 1

Pyruvate dehydrogenase activated and inhibited by

Answer 1

Activated: pyruvate, coASH, NAD+, ADP, insulin

Inhibited: acetyl-CoA, NADH, ATP, citrate

Question 2

Electron transport

Answer 2

Electrons on NADH and FAD2H transferred through a series

of carrier molecules to oxygen

Question 3

Oxidative phosphorylation

Answer 3

Free energy released used to drive ATP synthesis

Question 4

Proton motive force (pmf)

Answer 4

[H+] gradient (membrane potential) across inner mitochondrial
membrane

Question 5

Do electrons in NADH or FADH2 have more energy? How many PTCs do they use?

Answer 5

NADH

NADH uses 3 and FADH2 uses 2

Question 6

How many moles of ATP is produced from two moles of NADH and FADH2?

Answer 6

NADH synthesis of 5 moles of ATP (P/O = 2.5)

FADH2 synthesis of 3 moles of ATP (P/O = 1.5)

Question 7

How does cyanide inhibit the electron transport chain?

Answer 7

Prevents acceptance of electrons by O2

Question 8

Inhibitors of the electron transport chain

Answer 8

Cyanide and carbon monoxide

Block flow of electrons, no pmf

Question 9

Uncouplers

Answer 9

Dinitrophenol, dinitrocresol, fatty acids
Increase permeability of membrane to H+
H+ enters mitochondria without driving ATP synthetase
Dissipates p.m.f.

Question 10

Ox/Phos diseases

Answer 10

Genetic defects in proteins encoded by mtDNA

Decrease in electron transport and ATP synthesis

Question 11

Extra heat generation in brown adipose tissue

Answer 11

Thermogenin (UCP1)
In response to noradrenaline, lipase releases fatty acids from triacylglycerol. Oxidised fatty acids activate UCP1. Electron Transport uncoupled from ATP Synthesis. Energy of p.m.f. is then released as extra heat.

Question 12

Which vitamins cannot be synthesised in the body?

Answer 12

A D E K

Question 13

What is triacylglycerol made from?

Answer 13

Glycerol and fatty acids

Question 14

What do chylomicrons contain?

Answer 14

Fatty acids

Question 15

Hormone sensitive lipase in lipid metabolism stimulated and inhibited by…

Answer 15

Stimulated by glucagon and adrenaline

Inhibited by insulin

Question 16

What is used to transport fatty acids across the mitochondria membrane?

Answer 16

Carnitine shuttle

Question 17

Classes of lipids

Answer 17

Fatty acid derivatives
Hydroxy-methyl-glutaric acid derivatives
Vitamins

Question 18

Which processes produce and break down triacylglycerol?

Answer 18

Esterification and lipolysis

Question 19

What do chylomicrons transport?

Answer 19

Dietary triacylglycerol

Question 20

How are TAG released and transported in the circulation?

Answer 20

Lymphatics

Albumin fatty acid complex

Question 21

Fatty acid catabolism

Answer 21

Fatty acids activated by linking to coenzyme A
Transported across inner membrane using carnitine shuttle
Cycles through sequence of oxidative reactions, with C2 removed each time
FADH2 and NADH+H produced

Question 22

What links fatty acids to coenzyme A?

Answer 22

Fatty acyl CoA synthase

Question 23

When is carnitine shuttle transport inhibited and by what?

Answer 23

When energy levels are high

By malonyl CoA

Question 24

In which tissues does beta oxidation not occur?

Answer 24

Brain, RBC and WBC

Question 25

What does fatty metabolism stop in the absence of?

Answer 25

Oxygen

Question 26

What are the three ketone bodies produced in the body?

Answer 26

Acetoacetate Acetone Beta hydroxybutyrate

Question 27

What is the normal plasma body concentration? Starvation concentration? Concentration with untreated type 1 diabetes?

Answer 27

Normal <1 mM Starvation 2-10 mM physiological ketosis Type 1 diabetes >10 mM pathological ketosis

Question 28

Which enzyme converts HMG to mevalonate and in turn cholesterol?

Answer 28

HMG CoA reductase

Question 29

How is ketone body production controlled in the liver?

Answer 29

Low NAD substrate availability and high NADH inhibits enzymes isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase. Acetylcholine diverted from TCA cycle

Question 30

Which enzymes in ketone synthesis are inhibited and which are activated when the insulin:glucagon ratio is high?

Answer 30

Lyase is inhibited Reductase is activated Therefore cholesterol synthesis

Question 31

Which enzymes in ketone synthesis are inhibited and which are activated when the insulin:glucagon ratio is low?

Answer 31

Lyase is activated Reductase is inhibited Therefore ketone body synthesis

Question 32

What is ketonuria and ketoacidosis?

Answer 32

Ketonuria: high ketones in blood Ketoacidosis: acetoacetate and beta hydroxybutyrate are strong organic acids so cause acidosis