Class 5: Lipid Metabolism 1

Question 1

Lingual and gastric lipase affect what FAs?

Answer 1

Short and medium chain FA in TAG

Question 2

Suspension into small particles in the aqueous environment

Answer 2

Emulsification

Question 3

Emulsifiers thatre amphipathic

Answer 3

Bile salts

Question 4

Contraction of the GB to release bile salts and other pancreatic enzymes is stimulated by the gut hormone:

Answer 4

Cholecystokinin

Question 5

Digests all lengths of FA, Forms FA and 2-monoacylglycerol (2-MAG)

Answer 5

Pancreatic lipase

Question 6

Pancreas produces _______ which removes FA from cholesterol esters

Answer 6

Esterase

Question 7

Recognized by receptors on surface of liver cells allowing endocytosis

Answer 7

ApoE

IDL

Question 8

Activates lipoprotein lipase present on capillary endothelial cells in muscle and adipose tissue which digests chylomicrons

Answer 8

ApoCII

VLDL

Question 9

Released in response to acidic material.

Causes release of HCO3 which increases the pH to 6, optimal for intestinal enzymes.

Answer 9

Secretin

Question 10

Removes FA from phospholipids

Answer 10

Phospholipase A2

Question 11

These FA are absorbed directly into portal blood from intestinal epithelial cells

Answer 11

Short and medium chain FA

Question 12

TAG form micelles in intestinal lumen. Emulsified by bile salts. Absorbed acros microvili. Then the FAs and 2-MAGs are condensed again back to TAG and are packaged into chylomicrons. What is the major protein expressed on the outside of the chylomicron?

Answer 12

Apoprotein B48

Question 13

Where do the apolipoproteins (chylomicrons) take the TAG stores?

Answer 13

To the lymph system.

Question 14

Freshly made chylomicrons

Answer 14

Nascent chylomicrons

Question 15

Secreted y intestinal epithelial cells via exocytosis into the lymph system

Answer 15

Nascent chylomicrons

Question 16

Where does the chylomicrons enter the blood?

Answer 16

Thoracic duct - into the L brachiocephalic vein

Question 17

Nascent chylomicrons become mature chylomicrons when:

Answer 17

Nascent accepts proteins from HDLs

Question 18

Located on the surface of cells

Hydrolyzes the TG in the chylomicrons so they may be sent across plasma membrane into adipocytes

Answer 18

Lipoprotein lipase

Question 19

Utilization of FA req’s 3 steps:

Answer 19

1. Mobilization- TAGs in adipose are broken to FA and glycerol, released and transported to tissues in need of energy.
2. Activation- FAs 1st activated and transported to mito.
3. Degradation- stepwise breakdown of FA into acetyl CoA which is then processed in TCA.

Question 20

After mobilization, glycerol can be used:

Answer 20

In glycolysis to form pyruvate

Or

Gluconeogenesis to form glucose.

Both in the LIVER

Question 21

After mobilization, what happens to the FA from the adiposcyte?

Answer 21

It can be sent to tissue requiring energy and enter into the FA oxidation = then to TCA

Question 22

What is req’d for glycerol to be used in the liver…what enzyme?

Answer 22

Glycerol kinase after this reaction…

Glycerol can be taken into glycolysis,gluconeogenesis, or TAG synthesis.

Question 23

Activation of FA p/t oxidation:

Answer 23

FA becomes acyl Coa (forms a thioester bond) by Acyl-Coa Synthetase by a 2 step process req’s ATP

Question 24

Can the activation step be reversed in FA oxidation?

Answer 24

No it is irreversible b/c ATP hydrolysis –PPi hydrolysis makes it irreversible

Question 25

Once activated, how does call Coa enter the mito?

Answer 25

Carnitine translocase

Question 26

Steps in beta oxidation:

Answer 26

Acyl Coa OXIDIZED to trans-∆2-enoyl CoA by acyl CoA dehydrogenase

Trans-∆2-enoyl CoA HYDRATED to L-3-hydroxyacyl CoA by enoyl CoA hydratase

L-3-hydroxyacyl CoA OXIDIZED to 3-ketoacyl CoA by hydroxy acyl CoA dehydrogenase

3-ketoacyl CoA THIOLYZED to Acyl CoA and acetyl CoA by ketothiolase

Question 27

How many ATP for palmitate?

Answer 27

106 ATP (108 - 2 ATP for activation

Question 28

Odd numbered = FA requires:

Ex: palmitoleoyl CoA

Answer 28

Isomerase

[cis-∆3-enoyl CoA isomerase]

Question 29

Even numbered = FA requires

Ex: linoleoyl CoA

Answer 29

Isomerase and reductase

Cis-∆3-enoyl CoA isomerase

2,4-dienoyl CoA reductase

Question 30

Even numbered = FA gives rise to:

Where does this product travel?

Answer 30

Propionyl CoA and acetyl CoA

Propionyl CoA is converted to succinyl CoA which then enters the TCA cycle [this conversion req’s Vit B-12 (cobalamin)]

Question 31

What happens to acetyl coa from FA degradation ?

Answer 31

Entered TCA cycle if there is adequate OAA

If there isn’t OAA, acetyl CoA s not utilized (fats burn in the flame of carbs)–fats aren’t able to be used and ketone bodies accumulate

Question 32

3 names for ketone bodies.

Answer 32

Acetoacetate

D-3-hydroxybutyrate

Acetone

Question 33

How to get acetyl CoA from acetoacetate?

2 enzymes?

Answer 33

Acetoacetate converted to acetoacetyl CoA by CoA transferase

Acetoacetyl CoA converted to 2 acetyl CoA by thiolase