Lecture 26

Question 1

What are the three places fatty acids can be delivered from for fuel?

Answer 1

From the diet, liver or storage in the adipose tissue

Question 2

Why does the adipose tissue not make lipoproteins

Answer 2

Adipose lipase cleaves TAGs to give three FFAs and glycerol

Question 3

Why can’t fatty acids be delivered independently in the blood?

Answer 3

They are hydrophobic, the blood is hydrophilic

Question 4

How do fatty acids travel in the blood?

Answer 4

They bind to albumin

Question 5

What is albumin-FFA

Answer 5

A polar protein in the blood that has lots of slide chains that create hydrophobic pockets for the FFA to sit in

Question 6

How do FFAs travel in the polar cytosol of the cell?

Answer 6

Bound to the hydrophobic core of FABP, a polar protein

Question 7

What must happen before beta-oxidation?

Answer 7

Fatty acid activation

Question 8

When does fatty acid activation happen?

Answer 8

Before it enters the mitochondria

Question 9

How are fatty acids activated?

Answer 9

Energy is used to add a CoA to the FFA from hydrolysis of ATP to AMP

Question 10

What is a fatty acyl-CoA?

Answer 10

A carbon chain of any length

Question 11

What is an acyl-CoA?

Answer 11

A carbon chain

Question 12

What is an acetyl-CoA?

Answer 12

A two carbon chain

Question 13

How do fatty acids cross the outer mitochondrial membrane?

Answer 13

Passively, through the fatty acyl-CoA carrier

Question 14

How do fatty acids cross the inner mitochondrial membrane?

Answer 14

Through a carrier however, the fatty acyl-CoA requires the conversion to fatty acyl-carnitine

Question 15

What occurs in the intermembrane space?

Answer 15

The carnitine acyltransferase reaction

Question 16

What does the caritine acyltransferase reaction do?

Answer 16

Carnitine acyltransferase I enzyme removes fatty acyl-CoA and adds it to carnitine

Question 17

What happens after the fatty acyl-carnitine passes through the inner membrane?

Answer 17

Fatty acyl-carnitine is converted back to fatty acyl-CoA through the reverse reaction using carnitine acyltransferase II

Question 18

What is beta-oxidation?

Answer 18

The process by which the body breaks down fatty acids to produce energy

Question 19

Where does beta-oxidation occur?

Answer 19

In the mitochondrial matrix

Question 20

How is energy released in beta-oxidation?

Answer 20

It is released to carrier coenzymes NAD and FAD

Question 21

What is the product of beta-oxidation?

Answer 21

Acetyl-CoA

Question 22

What happens to acetyl-CoA after beta-oxidation?

Answer 22

It is further oxidised in the citric acid cycle

Question 23

What is FAD?

Answer 23

Flavin adenine dinucleotide, a coenzyme derived from vitamin B2

Question 24

How do flavin coenzymes bind to proteins?

Answer 24

Very tightly

Question 25

What is the common use for FAD?

Answer 25

To catalyse redox reactions

Question 26

What happens to FAD in redox reactions?

Answer 26

It undergoes a two electron reduction, accepting two reducing equivalents (H)

Question 27

What are the four reactions in beta-oxidation?

Answer 27

Oxidation, hydration, oxidation again and cleavage

Question 28

What happens in the first oxidation reaction in beta-oxidation?

Answer 28

1x H from each C (2x H total) are cleaved, oxidising the C-C bond to a C=C bond. FAD+ accepts both H to become FADH2

Question 29

What happens in the hydration reaction in beta-oxidation?

Answer 29

C=C is hydrated to form OH-C-C

Question 30

What happens in the second oxidation reaction in beta-oxidation?

Answer 30

2x H, one from the OH and one from C-beta are removed, oxidising the compound and forming a O=C bond. NADH accepts one H to become NADH2

Question 31

What happens in the cleavage reaction in beta-oxidation?

Answer 31

Acetyl-CoA is released as part of the C-alpha chain. The energy released while breaking the C-C bond is used to add a CoASH to beta chain forming the same fatty acyl-CoA, with two less carbons

Question 32

What are the products of beta-oxidation?

Answer 32

If 7 rounds = 7 NADH, 7 FADH2, 8 acetyl-CoA + some heat

Question 33

What is the equation to determine no. rounds in beta-oxidation?

Answer 33

No. rounds = n(C)/2-1

Question 34

Why is some heat released in beta-oxidation?

Answer 34

Reaction is not 100% efficient

Question 35

What is NAD derived from?

Answer 35

Vitamin B3

Question 36

What is FAD derived from?

Answer 36

Vitamin B2

Question 37

What is coenzyme A derived from?

Answer 37

Vitamin B5