Lipid transport

Question 1

How are free fatty acids formed? [1 mark]

Answer 1

From triacylglycerides in adipose tissue

Question 2

How are free fatty acids transported? [2 marks]

Answer 2

• Bound to plasma protein (e.g. albumin)

- As Na+ salt

Question 3

When does saturation of albumin by free fatty acids occur? [1 marks]

Answer 3

At 2mM FA molecules

Question 4

Types of lipoproteins [5 marks]

Answer 4

• Chylomicrons
• Very low density lipoproteins (VLDL)
• Intermediate density lipoproteins (IDL)
• Low density lipoproteins (LDL)
• High density lipoproteins (HDL)

Question 5

General structure of lipoproteins [3 marks]

Answer 5

• Single phospholipid layer with cholesterol
• Apolipoprotein
• TGs and cholesterol esters inside

Question 6

Which lipoprotein has the most TGs? [1 mark]

Answer 6

Chylomicrons

Question 7

Which lipoprotein has the most apolipoprotein? [1 mark]

Answer 7

HDL

Question 8

Which lipoprotein has apolipoprotein B48 (shortened version of B100)?

Answer 8

Chylomicrons

Question 9

Which lipoproteins have apolipoprotein B100? [3 marks]

Answer 9

• VLDL
• IDL
• LDL

Question 10

Which lipoproteins have apolipoprotein C1? [2 marks]

Answer 10

• VLDL

- HDL

Question 11

Which lipoproteins have apolipoprotein C2? [2 marks]

Answer 11

• Chylomicrons

- VLDL

Question 12

Which lipoproteins have apolipoprotein C3? [3 marks]

Answer 12

• Chylomicrons
• VLDL
• HDL

Question 13

Which lipoproteins have apolipoprotein E? [4 marks]

Answer 13

All except LDL

Question 14

Which lipoprotein has apolipoproteins A1 and A2? [1 mark]

Answer 14

HDL

Question 15

What are the functions of apolipoproteins? [4 marks]

Answer 15

• Structural
• Solubilise lipids
• Enzymes or cofactors
• Ligands/agonists

Question 16

When are apolipoproteins added? [1 mark]

Answer 16

SER

Question 17

Where are chylomicrons made? [1 mark]

Answer 17

Endothelial cells in blood vessels

Question 18

What do chylomicrons transport? [1 mark]

Answer 18

Fat soluble vitamins

Question 19

What is the lifetime of TGs in chylomicrons? [2 marks]

Answer 19

• Very short

- Broken down by lipoprotein lipases

Question 20

What are lipoprotein lipases in adiocyte activated by? [1 mark]

Answer 20

Insulin

Question 21

What do VLDLs/LDLs transport? [2 marks]

Answer 21

• Dietary lipids

- Liver lipids

Question 22

What is VLDL/LDL synthesis enhanced by? [5 marks]

Answer 22

• Dietary carbohydrates
• Circulating FFA
• Alcohol
• Raised insulin
• Decreased glucagon

Question 23

How are LDLs removed?

Answer 23

• 60% by the liver

- 40% used by non hepatic tissue for steroid biosynthesis

Question 24

Where are HDLs made? [2 marks]

Answer 24

• Liver

- Intestine

Question 25

What do HDLs do to cholesterol to remove it from the plasma? [1 mark]

Answer 25

Esterifies it with lecithin cholesterol acyltransferase (LCAT)

Question 26

Where are LDL and LDL like receptors found? [1 mark]

Answer 26

In the liver

Question 27

What are LDL and LDL like receptors regulated by? [1 mark]

Answer 27

Cholesterol

Question 28

What is the affinity for LDL and LDL like receptors to their ligands? [1 mark]

Answer 28

High

Question 29

Which lipoproteins are LDL receptors on? [2 marks]

Answer 29

- VLDL | - LDL

Question 30

Which lipoproteins are LDL like receptors on? [3 marks]

Answer 30

- VLDL - HDL - Chylomicrons

Question 31

What is the ligand for LDL receptors? [1 mark]

Answer 31

Apo B100

Question 32

What is the ligand for LDL like receptors? [1 mark]

Answer 32

Apo E

Question 33

What does high levels of cholesterol do to HMG-CoA reductase activity? [1 mark]

Answer 33

Inhibits it (inhibits cholesterol production)

Question 34

What does low levels of cholesterol do to LDL receptor expression? [1 mark]

Answer 34

Increases it

Question 35

Where are scavenger receptors found? [2 marks]

Answer 35

- Endothelial cells | - Macrophages

Question 36

What are lipoproteins regulated by? [3 marks]

Answer 36

- Hormones - Nutritional status (starvation decreases synthesis) - LDL expression affected by hormones (like oestrogen)

Question 37

How is lipid transport affected by diabetes?

Answer 37

- Increased FFA mobilisation | - Decreased chylomicron and VLDL utilisation

Question 38

Where do chylomicrons enter circulation? [1 mark]

Answer 38

Via thoracic duct

Question 39

How is cholesterol excreted? [1 mark]

Answer 39

As bile salts