Flashcards in Chapter 12 Deck (59)
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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
