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1

Define triacylglycerols

long term energy molecules

2

Why is fat a better storage molecule?

It is more reduced and compact
- when it is oxidized it produces much more energy
- can store more of it

3

Define Acetyl-CoA

energy rich molecules composed of coenzyme A and the acetyl group (2C) that plays a major role in the metabolism of lipids

precursor in fatty acid synthesis and cholesterol synthesis

4

How do we get fats into small intestinal cells where they can be properly digested?

Bile Salts
- help to emulsify triacylglycerols into smaller fat globules to make it easier for the enzyme to work
-lipase enzyme can then digest it into its monomer units (fatty acids and monoglycerols)

5

What happens when the monomer groups of triacylglycerols are absorbed into the small intestine?

Transported to enterocytes where most of the digestion occurs and are then reconverted back to triacylglycerols. They then combine with phospholipids into the lipoprotein chylomicron

6

Define chylomicron

a lipoprotein composed to triacylglyercols combined with phsopholipids

lipoprotein that packages fat and travels through the lymphatic system

7

What happens to most of the triaglycerol content circulating in chylomicrons?

removed by skeletal muscle and adipose tissue cells

broken down by lipoprotein lipase into fatty acids and glycerol

8

Define lipolysis

when energy reserves are low the body's fat stores are mobilized

occurs during fasting, vigorous exercise, response to stress

9

what is responsible for transporting the fatty acids into target organelles?

Fatty acid binding proteins

- fats are mainly lipid-soluble so they need a binding protein

10

How is triaglycerol lipase activated?

Epinephrine binds to membrane receptors on adipocytes

11

What happens to glycerol and fatty acids once released into the blood by lipoprotein lipase?

glycerol is transported back to the liver

fatty acids are bound to albumin in the blood and carried to tissues to be taken up by Active transport
- used for energy proaction or as metabolic intermediates

12

Where does fatty acid degradation take place?

Mitochondrial matrix

13

What is Beta Oxidation and what are the three steps?

the sequential removal of two carbon fragments from the carboxyl end of a fatty acid

1. Activation
2. Transport
3. B Oxidation

14

What activates B Oxidation?

acyl-CoA synthetase

to transport Acyl-CoA into inner membrane space of mitochondria

15

Mechanism by which Carnitine mediated transfer of acyl groups is accomplished?

1. Acyl-CoA is converted to acetylcarnitine
2. Carrier protein transfers acetylcarnitine into matric
3. Acyl-CoA regenerated
4. Carnitine is recycled to intermembrane space

16

Acetyl CoA molecules produced in B Oxidation are used where?

Citric acid cycle

17

Step 1 of Beta Oxidation

formation of a trans double bond

-takes place in the matrix
-Acyl CoA is oxidized to Enoyl CoA
-FAD reduced to FADH
-enzyme: Acyl-CoA dehydrogenase

18

Step 2 of Beta Oxidation

Beta carbon experiences addition of water and hydroxyl group

- Enoyl CoA is converted to Hydroxyacyl CoA
- enzyme: Enoyl-CoA hydrase

19

Step 3 of Beta Oxidation

Oxidation of the beta carbon to for a C=O

- Hydroxyacyl-CoA is converted to Ketoacyl-CoA
- enzyme: Hydroxyacyl CoA dehydrogenase
- NAD+ reduced to NADPH

20

Step 4 of Beta Oxidation

Thiolytic cleavage

- Ketoacyl CoA is converted to Acyl CoA + Acetyl CoA
- enzyme: Thiolase
- addition of CoAsh; allows the rest of fat to be an acyl CoA

21

Mechanism by which Carnitine mediated transfer of acyl groups is accomplished?

1. Acyl-CoA is converted to acetylcarnitine
2. Carrier protein transfers acetylcarnitine into matric
3. Acyl-CoA regenerated
4. Carnitine is recycled to intermembrane space

22

Acetyl CoA molecules produced in B Oxidation are used where?

Citric acid cycle

23

Step 1 of Beta Oxidation

formation of a trans double bond

-takes place in the matrix
-Acyl CoA is oxidized to Enoyl CoA
-FAD reduced to FADH
-enzyme: Acyl-CoA dehydrogenase

24

Step 2 of Beta Oxidation

Beta carbon experiences addition of water and hydroxyl group

- Enoyl CoA is converted to Hydroxyacyl CoA
- enzyme: Enoyl-CoA hydrase

25

Where does ketogenesis occur?

liver of mitochondria

26

Step 4 of Beta Oxidation

Thiolytic cleavage

- Ketoacyl CoA is converted to Acyl CoA + Acetyl CoA
- enzyme: Thiolase
- addition of CoAsh; allows the rest of fat to be an acyl CoA

27

Mechanism by which Carnitine mediated transfer of acyl groups is accomplished?

1. Acyl-CoA is converted to acetylcarnitine
2. Carrier protein transfers acetylcarnitine into matric
3. Acyl-CoA regenerated
4. Carnitine is recycled to intermembrane space

28

Acetyl CoA molecules produced in B Oxidation are used where?

Citric acid cycle

29

Where does fatty acid biosynthesis occur?

LIVER

when diet is too low in fat or high in carbs/protein

large quantity of NADPH required
-- obtained from pentose phosphate pathway

30

Step 2 of Beta Oxidation

Beta carbon experiences addition of water and hydroxyl group

- Enoyl CoA is converted to Hydroxyacyl CoA
- enzyme: Enoyl-CoA hydrase