Lipids 2

Question 1

In the beta oxidation pathway, how many fatty acid carbons does it break down at a time?

Answer 1

2

Question 2

What are the products of beta oxidation?

Answer 2

Acetyl CoA, NADH, and FADH2 all sources of energy for ATP

Question 3

Where does beta oxidation occur?

Answer 3

In the mitochondrial matrix

Question 4

What does FA released from an adipocyte bind to?

Answer 4

Albumen

Question 5

What are the 3 stages of beta oxidation?

Answer 5

Activation, transport and degradation

Question 6

How is the fatty acid activated?

Answer 6

It is involved in a reaction using ATP to form fatty acyl co a in the CYTOPLASM (of the target tissue)

Question 7

How does the fatty acyl co a cross the mitochondrial walls?

Answer 7

Fatty acyl co a diffuses across the first membrane. The carnitine shuttle is responsible for the movement of the fatty acyl co a across the second membrane- Co a component of the molecule is removed, remaining molecule then binds to carnitine and passes over the membrane with help from translocase. Carnitine is removed and fatty acyl co a is reformed

Question 8

What is the effect of malonyl co a?

Answer 8

Inhibits the transferase enzymes, preventing further degradation of the fatty acid. Malonyl is needed for FA synthesis - therefore prevent the synthesis and degradation happening at the same time.

Question 9

What is the effect of carnitine fatty acyl tranferase or carnitine palmitoyl transferase deficiency?

Answer 9

No beta oxidation
Hypoglycemia

Question 10

What are the steps of degradation?

Answer 10

Dehydrogenation - produces FADH2
Hydration - Requires H20
Dehydrogenation- To produce NADH
Thyolysis- Cleaved to produce acetyl co a

Question 11

What is the precursor of FADH2 and NADH

Answer 11

FADH2 = FAD
NADH = NAD+

Question 12

What happens to acetyl co a produced?

Answer 12

Joins TCA cycle (citric acid cycle)

Question 13

What carbon products are produced after every beta oxidation cycle?

Answer 13

A carbon species two carbons shorter than the original + acetyl co a

Question 14

How much ATP does each of the following molecules give / use?
FADH2
NADH
Acetyl Co A

Answer 14

FADH2 = 2 ATP
NADH = 3 ATP
Acetyl Co a = 12 ATP

Question 15

Where does a preliminary beta oxidation of very long fatty acids take place?

Answer 15

Peroxisomes

Question 16

Why is the first step (dehydrogenation) less energy efficient?

Answer 16

No FADH2 is produced

Question 17

What happens to the FA linked to the carnitine?

Answer 17

Diffuses from peroxisome to mitochondria for further oxidation

Question 18

What happens to acetyl co a levels during fasting / starvation?

Answer 18

Liver flooded with acetyl co a

Question 19

What is the effect of high acetyl co a levels on pyruvate dehydrogenase?

Answer 19

Pyruvate dehydrogenase is inhibited reducing further acetyl co a formation?

Question 20

What is the effect of high acetyl co a levels on pyruvate carboxylase?

Answer 20

Activates pyruvate carboxylase and therefore increases the oxaloacetate present

Question 21

What does the amount of ketogenesis depend on?

Answer 21

The amount of acetyl co a, excess is converted into ketone bodies

Question 22

What muscles use ketone bodies as an energy source?

Answer 22

The skeletal muscles, and the cardiac muscles

Question 23

What important organ can ketone bodies also provide energy for?

Answer 23

The brain

Question 24

Where are ketone bodies formed?

Answer 24

The liver, although the liver cannot actually use them!

Question 25

How are ketone bodies transported from the liver?

Answer 25

In the blood to other tissues, they are soluble and do not need albumen or lipoprotein

Question 26

What can lead to very high levels of ketone bodies in the blood?

Answer 26

Starvation or uncontrolled diabetes

Question 27

What can result from a higher build to use ratio of etone bodies?

Answer 27

Ketonemia, ketonuria and acidosis
fruity breath odour due to acetone