Lipids

Question 1

What are some properties of lipids

Answer 1

Heterogenous
Insoluble in water
Exist in cell membranes

Question 2

What are the different lipid classes

Answer 2

F.A
Triacylglycerol
Phospholipid
Glycolipid
Steroids

Question 3

What are the essential FA and where do we get them from?

Answer 3

Linoleic
Linolenic
We get from plants

Question 4

What are triacylglycerols

Answer 4

Esters of FAs and glycerol
TAG major lipid in adipose tissue
Used for fuel and insulation

Question 5

What are the properties of phospholipids

Answer 5

Amphipathic:
Glycerol + 2FA+ phosphate group
Contain a Hydrophilic head and hydrophobic tail

Question 6

What are the Main Steroids

Answer 6

Cholesterol
Steroid hormones
Bile salts

Question 7

Properties of cholesterol

Answer 7

-Precursor to Sterol hormones and bile salts
-Made in liver
-Found in animal food

Question 8

How is cholesterol synthesis regulated

Answer 8

Via statins
Inhibit HMG-CoA reductase

Question 9

What are eicosanoids and what do they regulate?

Answer 9

Lipid class derived from 20C unsaturated FA
Regulate:
inflam response
B.p
clotting
Pain & fever

Question 10

What is the main dietary lipid

Answer 10

Triacylglycerol

Question 11

What is the main site of lipid digestion

Answer 11

small intestine

Question 12

What are lipids digested by

Answer 12

Lipases via emulsification by bile salts and mixing

Question 13

What are bile salts

Answer 13

Biological detergents
Derivative of cholesterol

Question 14

How is TAG digested

Answer 14

In small intestine via pancreatic lipase->monoacylgycerol + 2FA

Question 15

What is cholesterol esters digested to

Answer 15

Cholesterol and free FA

Question 16

How are phospolipids digested

Answer 16

Hydrolysed to FA and lysophospholipid

Question 17

How are digested lipids uptaken

Answer 17

Form mixed miscelles with bile salts
Enter cells via diffusion

Question 18

How are absorbed FA transported

Answer 18

Packaged into chylomicrons
Released by exocytosis into lymph then blood

Question 19

Summary of lipid digestion

Answer 19

Bile salts emulsify dietary fats in the small intestine
Intestinal lipases degrade triglycerol
Fatty acids and other breakdown products are absorbed by the intestinal mucosa and converted to triaglyceroids.
Triaglycerols are incorporated with cholesterol
Lipoprotein lipase converts triaglycerols into fatty acids
Fatty acids enter cells
Fatty acids are oxidized as fuel

Question 20

How are FA transported in blood

Answer 20

Serum albumin
Esterified FA carried in lipoproteins

Question 21

What do lipoproteins carry

Answer 21

TAG, cholesterol

Question 22

What are the lipoprotein classes

Answer 22

Chylomicrons
VLDL
LDL
HDL

Question 23

What are the fates of FA after metabolism in plasma

Answer 23

Oxidation - energy
TAG formation
FA->Fatty acetyl CoA->Triglyceride

Question 24

What does B-oxidation of FAs involve

Answer 24

Degrades FA 2 carbons at a time
Produces acetyl CoA +NADH + FADH2
Occurs in mitochondrial matrix

Question 25

What happens on B-oxidation

Answer 25

1. Activation of FA in cytosol
2. Transport into mitochondria
3. Degredation to 2C in mitchondrial matrix

Question 26

What does transport of FA involve

Answer 26

Carnitine shuttle

Question 27

What are the 4 degredation steps of B-oxidation

Answer 27

1. Dehyrdrogenation FAD->FADH2
2. Hydration
3. Dehydrogenation NAD+->NADH
4. Thiolysis- produces acetyl CoA for CAC

Question 28

What happens during starvation

Answer 28

Excess acetyl CoA from fat metabolism converted to ketone bodies

Question 29

What are ketone bodies used for

Answer 29

Cardiac and skeletal muscles use it as energy source
Fuels brain cells during starvation

Question 30

Where does FA synthesis occur

Answer 30

Liver
Mammary gland
Adipose tissue

Question 31

FA synthesis and degredation

Answer 31