Fat transport and Metabolism

Question 1

Describe the bonds in triglycerides?

Answer 1

ESTER LINKAGES-help to neutralise the carboxylic acid groups and hence keep the pH within the cells at a normal range

Question 2

Why are fatty acids an ideal storage molecule ?

Answer 2

Because they are reduced and anhydrous

Question 3

Show the breakdown of major food groups to produce acetyl CoA?

Answer 3

Polysaccarides->monosaccarides->glucose->pyruvate->Acetyl CoA

Fats->fatty acids->Acetyl CoA

Acetyl CoA generated in the mitochodria

Question 4

What are the 3 primary sources fat are derived from?

Answer 4

• de novo biosynthesis in the liver
• storage deposits in adipose tissue
• The diet

Question 5

Why are fats hard to digest and what is the solution?

Answer 5

• They are HYDROPHOBIC so dont mix well with water

- BILE SALTS emulsify fats =aids in their digestion and absorption and also that of fat soluble vitamins(A, D, E, K)

Question 6

Where are bile salts generated, stored and used?

Answer 6

• generated in the LIVER
• stored in the GALL BLADDER
• passed into the intestine

Question 7

What happens if their is a lack of bile salts?

Answer 7

majority of fats pass throught he gut undigested and unabsorbed -STEATORRHEA(fatty stool)

Question 8

What can we do to help obesity?

Answer 8

• Inhibit gastric+pancreatic LIPASES e.g. use ORLISTAT

- This reduces fat absorption by 30%, and excretes it instead

Question 9

What are the side effects of Orlistat?

Answer 9

• abdominal pain
• urgency to defecate
• increased gas

Question 10

How do we transport lipids around the body in aqueous blood?

Answer 10

• Lipids are hydrophobic

- so transport via LIPOPROTEINS

Question 11

What are the different types of lipoproteins, their source and role?

Answer 11

CHYLOMICRONS:
Souce-Intestines
Role-dietry fat transport

VERY LOW DENSITY LIPOPROTEINS:
Source-Liver
Role-Endogenous fat transport(fats originating in the liver)

INTERMEDIATE DENSITY LIPOPROTEINS:
Source-VLDL
Role-LDL precursor

LOW DENSITY LIPOPROTEINS
Source-IDL
Role -Cholestrol transport

HIGH DENSITY LIPOPROTEINS:
Source-liver
Role-Reverse Cholestrol transport

Question 12

What is the life cycle of Lipoproteins?

Answer 12

1-VLDL synthesised by the liver and deliver triglycerides and cholesterol to the muscle and adipose
2-Lipid depleted VLDL pass apoproteins onto HDL and becomeIDL
3-IDLs pick up cholestrol esters from HDL and become LDLs which can be taken up by the liver and cleared from circulation or taken up by macrophages