Lipid Catabolism and Ketogenesis

Question 1

Why are triacylglycerols more efficient form of energy storage than glycogen?

Question 2

Where are triacylglycerols stored? (What type of cell?)

Question 3

What hormone stimulates the release of free fatty acids when blood glucose levels fall?

Answer 3

Glucagon

Question 4

Why must free fatty acids be converted into acyl-CoA efficiently?

Question 5

How are free fatty acids transported in the circulation?

Question 6

What are the three chemical steps that fatty acids are activated for Beta-Oxidation from the formation of acyl-CoA?

Question 7

What reaction ensures that the overall biochemical standard free energy is large and negative in the activation for Beta-oxidation?

Question 8

Where does Beta-oxidation take place?

Question 9

What is a “carnitine shuttle?”

Question 10

What is the function of a carnitine shuttle?

Question 11

What re the key features of a carnitine shuttle?

Question 12

How are fatty acyl groups transported from the cytosol to the matrix?

Question 13

What are the four reactions of one round of Bata-oxidation? (Know the structures)

Question 14

How does a pair of electrons enter the mitochondrial electron transport chain from FADH2?

Question 15

Is there a difference in the amount of ATP formed by even and odd-chain fatty acid oxidation?

Question 16

Name the for important componenets of a lipid bilayer

Answer 16

1. Glycerophopholipids
2. Cholesterol
3. Sphingolipids
4. Proteins and carbohydrates

Question 17

Name 4 functions of membranes.

Answer 17

1. Provide a barrier
2. Compartmentalization of metabolic pathways
3. Hold metabolites
4. Provide gradients

Question 18

What is the hydrophobic effect?

Question 19

What type of interactions will be found between the fatty acid tails of phospholipids in a membrane?

Question 20

What influences the function of membrane lipids?

Answer 20

Shape causes function
- triangular (up and down facing)–does not form membranes alone
- rectangular–membrane forming, rigidifies
- Short rectangular–fluidizes the membrane

Question 21

How does chain length of a fatty acid affect solubility?

Answer 21

Solubility decreases as the length increases

Question 22

How does the number of double bonds in a fatty acid tail affect solubility?

Answer 22

Solubility increases as the number of double bonds increases

Question 23

How does chain length of a fatty acid affect melting point?

Answer 23

As chain length decreases, the melting point decreases.

Question 24

How does the number of double bonds affect the melting point of a fatty acid?

Answer 24

The melting point decreases as the number of double bonds increases.

Question 25

When considering the effect of double bonds of solubility and melting point, how many does carbons do we simulate each double bond to?

Answer 25

One double bond is about 4 less carbons (-4)

Question 26

What is optimal fluidity?

Question 27

What influences the fluidity of the membrane?

Answer 27

1. Temperature 2. Fatty acid composition

Question 28

Explain why a longer and more saturated fatty acid membrane make-up causes less fluidity

Answer 28

There are more Van der Wals interactions which leads to higher TM and therefore less fluidity

Question 29

Explain why short and less saturated fatty acid membrane make up leads to more fluidity

Answer 29

There are less Van der Wals interactions which leads to a lower TM and therefore more fluidity

Question 30

Which lipids do Oligosaccarides sit on?

Answer 30

Glycoconjugate lipids

Question 31

Explain the absorptionof dietary fats

Question 32

How is energy generated from a TAG

Question 33

What is a TAG

Answer 33

Triacylglycerol

Question 34

How do we release fatty acids from stored TAG?

Answer 34

Triggered by Glucagon signals for low blood glucose which stimulates the release of fatty acids. Triacylglycerol and water ---lipases---> 3 fatty acids and a glycerol

Question 35

What are micelles?

Answer 35

Spherical shapes of free fatty acids

Question 36

How are micelles formed?

Answer 36

free fatty acids interacting with eachother

Question 37

Free fatty acids form what?

Answer 37

Micelles

Question 38

True or False. Free fatty acids form micelles that may act as detergents.

Answer 38

True

Question 39

True or False. Cells will keep the concentration of free fatty acids in very high concentrations.

Answer 39

False. Cells keep them in low concentrations. In cells they are rapidly converted to acylCoA or converted to TAG

Question 40

What do free fatty acids do in the blood circulation?

Answer 40

They bind to serum albumin

Question 41

What is Beta Oxidation?

Answer 41

Fatty acid oxidation

Question 42

What are the two phases of Beta-oxidation?

Answer 42

1. Activation of fatty acids (conversion of fatty acids to acyl CoA) 2. Beta-oxidation (Acyl CoA is converted to acetylCoA) *MITOCHONDRIAL MATRIX*