Lipids (transport/storage/oxidation)

Question 1

What are the functions of a fatty acid?

Answer 1

It is a direct fuel source

A cell membrane constituent and is involved in cell signaling

Question 2

What is esterification?

Answer 2

The formation of a bond (ester bond) between an alcohol and an organic acid with the removal of water

Question 3

How are glycerides formed?

Answer 3

By the process of esterification

Question 4

What are some functions of triglycerides?

Answer 4

• A storage of fuel
• They are the largest fuel store in the body
• The splitting of triglycerides liberates fatty acids

Question 5

What are phospholipids made up of and what is their main function?

Answer 5

Fatty acid, phosphate, a backbone (normally glycerol) and alcohol

Main function is the lipid bilayer

Question 6

What are phosphoglycerides?

Answer 6

Derived from phosphotidate and alcohol

Inositol,choline and serine can combine with phosphotidate to form a phosphoglyceride

Question 7

What is cholesterol?

Answer 7

• A cell membrane and a blood lipid
• required to build and maintain cell membranes and regulate fluidity
• used in the formation of other circulating steroid hormones
• required for formation of bile salts used in lipid digestion

Question 8

What happens if the lipid is not water soluble (isn’t stored/utilized straight away)

Answer 8

It requires transport in the blood

Question 9

What do lipoproteins do?

Answer 9

They carry TG and cholesterol in the blood stream

VLDL and LDL carry cholesterol/TG from the liver and tissues
HDL carries cholesterol/TG from bloodstream back to liver for recycling

Question 10

Can fatty acids be transported in the blood?

Answer 10

Yes, not only as triglycerides in lipoproteins

99.9% of all FFA in plasma are
Bound to albumin

Question 11

Is more energy stored in adipose tissue or glycogen?

Answer 11

Adipose! 108,000 compared to 2,000

Question 12

How do the triglycerides provide fuel for exercise?

Answer 12

TG can be broken down to fatty acids in both adipose tissue and muscle

Question 13

Are triglycerides taken into adipocytes?

Answer 13

No, they are first hydrolysed to fatty acids by LPL

Then the fatty acids are freed in capillaries by LPL and flow down a concentration gradient into adipocytes with the aid of a carrier protein

Question 14

Describe the set of stages in using fatty acids as a fuel for exercise?

Answer 14

• mobilization - lipolysis, adipose tissue/IMTG/VLDL-TG
• transport into blood stream (FA with albumin)
• transport into the muscle cell - transport into mitochondria
• oxidation in beta-oxidation pathway and TCA cycle

Question 15

How do adrenaline and insulin affect the mobilization of lipid fuel from adipose tissue?

Answer 15

Adrenaline increases the hormone sensitive lipase which breaks down TG to glycerol and 3FFA which then go into the capillary

Insulin decreases this enzyme

Question 16

Explain fatty acid uptake in muscle?

Answer 16

VLDL/chylomicron broken down to FA by LPL. The FA then use a transport protein to get Into the muscle

Also FA from the blood bound to albumin go through same process

Question 17

What is fatty acid muscle uptake directly related to?

Answer 17

Plasma FFA concentration

Question 18

By what process does transport across the membrane into muscle (fatty acids) occur

Answer 18

Facilitated diffusion

Question 19

Can the FA transporter protein become saturated?

Answer 19

Yea it can, an increase of lipolysis = an increase of glycerol in the blood

Question 20

What happens to the fatty acids upon uptake into muscle

Answer 20

They are converted to a conenzyme A derivative

Where preparation for B-oxidation occurs, this priming reaction requires ATP catalyses by fatty-acyl-CoA synthetase

Question 21

How are the fatty acyl-CoA molecules transported from the muscle sarcoplasm into the mitochondria?

Answer 21

Via an ester bond with carnitine (can’t just diffuse across)

Question 22

Discuss carnitine

Answer 22

Carnitine is synthesised by liver from methionine and lysine and derived from the diet, it is present in tissues that are able to oxidise fatty acids

Question 23

What is the key enzyme in beta oxidation?

Answer 23

3-HAD

Question 24

Where does beta-oxidation occur?

Answer 24

In the mitochondrial matrix

Question 25

What is beta-oxidation?

Answer 25

The sequential removal of 2 carbon fragments from a fatty acid which yields the produces acetyl CoA, NADH and FADH2 (oxidized in ETC)

Question 26

What does beta oxidation produce ATP wise?

Answer 26

It produces 5 ATP molecules per 2 carbon acetyl-CoA unit cleaved from the FFA chain

Question 27

Where do the ATP produced in beta oxidation come from?

Answer 27

3 ATP from NADH

2 ATP from FADH2