Lipids

Question 1

What are lipids

Answer 1

Heterogenous molecules

Insoluble in water

Question 2

Biological functions

Answer 2

Energy storage
Structural
Enzyme cofactors
Hormones
Vitamins A,D, E,K
Signalling

Question 3

Major lipid classes (5)

Answer 3

Fatty acids
Triaglycerol
Phospholipid
Glycolipid
Steroids

Question 4

Fatty Acids

Answer 4

Unstaurated- double bond
Saturated- single bond
Essential- humans cannot introduce double bonds begone carbon 9

Question 5

Triacylglycerol

Answer 5

Esters of Fatty acids and glycerol
Main dietary lipid
Most degraded in small intestine to monoacylglycerol and 2 FA

Question 6

Phospholipids

Answer 6

Glycerol bound to 2 fatty acids and phosphate molecule

Question 7

Bile salts

Answer 7

Biological detergents- emulsions and mixed micelles

Derivatives of cholesterol

Question 8

Steatorrhea

Answer 8

Lipid malabsorption due to defects in bile secretion, pancreatic function or intestinal cell
Fat in faeces

Question 9

Utilisation of Dietary Lipids

Answer 9

1. Bile salts and dietary fats form mixed micelles
2. Intestinal lipases degrade TAG
3. Brush border of enterocytes and enter mucosa by diffusion
4. TAG are packaged with apoB-48 into chylomicrons
5. Chylomicrons travel through lymphatic system
6. TAG are converted to FA and glycerol
7. FA used as fuel or resterfied, glycerol&raquo_space; G3P

Question 10

Synthesis and Storage of TAG

Answer 10

TAG is stored in adipose tissue

Question 11

How are FA released from TAG store

Answer 11

Hormone sensitive lipase is activated when phosphorylated in response to epinephrine when blood glucose and insulin is low

Question 12

How are FA transported in the blood

Answer 12

Free FA is transported in a complex with serum albumin

Question 13

Lipoproteins

Answer 13

Core full of fat and cholesterol along with apolipoporoteins

Question 14

Classes of Lipoproteins

Answer 14

Chylomicrons
VLDL
LDL
HDL

Question 15

B oxidation of fatty acids

Answer 15

Activation: fatty acyl CoA using ATP
Transport to mitochondria: Carnitine (CAT-1)
Degradation: 
Dehydrogenation = FADH2
Hydration = H2O
Dehydrogenation = NADH
Cleavage = Thiolysis = acetyl CoA

Question 16

Synthesis of Fatty acids

Answer 16

Acyl group + malonyl group
Elongation- condensation
Reduction- NADPH
Dehydration = H2O
Reduction- NADPH
FA cleavage

Question 17

Steroids hormones

Answer 17

Chemical substances that serve as chemical messengers in the body
Testosterone, progesterone

Question 18

Eicosanoids

Answer 18

Precursor from prostaglandins, thromboxane and leukotreines

Signalling molecules derived from Omega 3 and 6

Question 19

Cholesterol

Answer 19

Precursor for:
Bile
Vitamin D
Steroid hormones
Membranes
Plasma lipoproteins

Question 20

Statins

Answer 20

Inhibit HMG-CoA reductase- essential in cholesterol synthesis

Question 21

COX inhibitors

Answer 21

inhibition of COX enzyme
Prostaglandin synthesis
and thromboxane synthesis

Question 22

Ketone bodies are formed in the____

Answer 22

Liver

Question 23

B-oxidation occurs in the_____

Answer 23

Mitochondria

Question 24

Fatty acid synthesis occurs in the _____

Answer 24

Cytosol

Question 25

What organs and tissues does fatty acid synthesis occur in

Answer 25

Liver
Lactating mammary gland
Adipose tissue

Question 26

Citrate shuffle is used to_____

Answer 26

Move acetyl CoA out of mitochondria

Question 27

Acetyl CoA carboxylase

Answer 27

activation and regulation