Lecture 25 - Fatty acids as a fuel molecule #1

Question 1

What is the chemical nature of lipids?

Answer 1

Hydrophobic or amphiphilic organic molecules

Question 2

What are the three forms of lipid in the diet?

Answer 2

Phospholipids (membrane) , sterols, triacylglycerol

Question 3

What is an example of a sterol?

Answer 3

Cholesterol

Question 4

What is the role of cholesterol in the body?

Answer 4

A range including membranes, signalling (hormones) and forming bile salts

Question 5

What is the chemical structure of cholesterol?

Answer 5

A hydrophobic ring structure

Question 6

What is an example of a triacylglycerol (TAGs)?

Answer 6

fatty acids

Question 7

What is a fatty acid?

Answer 7

Carbon chain attached to a carboxylic acid

Question 8

What is a free fatty acid (FFA)?

Answer 8

A fatty acid not bound to any other molecule

Question 9

What is the chemical nature of the carbon chain in fatty acids?

Answer 9

Hydrophobic

Question 10

What is the structure of a triagylglycerol?

Answer 10

1x Glycerol (3C) with 3x fatty acids (acyl groups) attached

Question 11

What component of the TAG is polar?

Answer 11

Glycerol

Question 12

What component of the TAG is non-polar?

Answer 12

fatty acid (acyl group)

Question 13

What type of enzyme breaks down TAGs?

Answer 13

Lipase

Question 14

What does lipase do to TAGs?

Answer 14

Hydrolyses it to release the free fatty acids (FFAs)

Question 15

What are bile acids?

Answer 15

Salts synthesised from cholesterol in the liver

Question 16

How are bile acids synthesised?

Answer 16

By adding hydroxyl and/or carboxyl groups to create a hydrophilic face

Question 17

What do bile acids form?

Answer 17

Micelles, multiple bile acids come together to form a hydrophobic core of TAGs inside to be absorbed into epithelial cells

Question 18

What are exogenous fatty acids?

Answer 18

Fatty acids ingested from the diet

Question 19

What is the path of exogenous fatty acid transport to the blood stream?

Answer 19

Consumed fats exist as TAGs, bile salts break these down into smaller droplets, pancreatic lipase breaks these down into MAG and 2FFAs which are then rearranged to form a micelle for transportation to SI lining for absorption. Once absorbed MAG and 2FFAs are rearranged back into a TAG which are packaged into chylomicrons along with apoproteins to enter capillaries

Question 20

What is a chylomicron?

Answer 20

A type of large lipoprotein involved in TAG transport with low protein:lipid (~1:50)

Question 21

What is a lipoprotein?

Answer 21

A type of ‘delivery system’ for lipid transportation, to help solubilise them

Question 22

What are the components of a lipoprotein?

Answer 22

Phospholipids, unesterified cholesterol, esterified cholesterol, TAGs and apoproteins

Question 23

What is unesterified and esterified cholesterol

Answer 23

Cholesterol without and with FFAs attached (respectively)

Question 24

What is an apoprotein?

Answer 24

The protein component of the lipoprotein that can have several roles including; structural, ligand for receptors and enzyme co-factors

Question 25

What are the classes of lipoprotein?

Answer 25

Chylomicron, VLDL, LDL, HDL

Question 26

What is a VLDL?

Answer 26

Very low-density lipoprotein involved in TAG transport with medium lipid:protein (~1:9)

Question 27

What is a LDL?

Answer 27

Low-density lipoprotein involved in cholesterol transport

Question 28

What is a HDL?

Answer 28

High-density lipoprotein involved in cholesterol regulation

Question 29

What happens to the chylomicron once it enters the blood stream?

Answer 29

Lipoprotein lipase hydrolyses the TAG into monoacylglycerol and fatty acids to enter the tissue

Question 30

What is lipoprotein lipase activated by?

Answer 30

ApoCll

Question 31

What happens to chylomicron remnants after?

Answer 31

They remain in blood

Question 32

What can fatty acids be used for?

Answer 32

Fuel or storage

Question 33

What is the preferred fuel for most tissues?

Answer 33

Fatty acids

Question 34

Red Muscle Cells tend to use?

Answer 34

Fat (endurance)

Question 35

White muscle cells tend to use?

Answer 35

Glucose (sprinting)

Question 36

Why are fatty acids the preferred storage molecule?

Answer 36

Fatty acids are more reduced than carbohydrates (more energy released when oxidised) Also takes up less room than carbohydrates (due to carbohydrates water retention)

Question 37

Acetyl-CoA can be formed into ____ to make ____

Answer 37

Free fatty acids to make TAGs

Question 38

Chylomicron remnants are absorbed in the?

Answer 38

Liver via receptors that recognise ligands on chylomicrons

Question 39

Chylomicron remnants are recycled into:

Answer 39

VLDL (with TAGs) Bile salts and cholesterol

Question 40

What can remove TAGs from VLDL to make LDL?

Answer 40

Hepatic Lipase