Lecture 2

Question 1

How does fatty acid oxidation begin

Answer 1

with activation; due to ATP

Question 2

How is fatty acid activated

Answer 2

the formation of a thioester bond between carboxyl group of the FA and the thiol of the CoA-SH

Question 3

true or false; the resulting CoA ester during fatty acid activation is more soluble

Answer 3

true

Question 4

What is the enzyme for fatty acid activation

Answer 4

acyl CoA synthetase

Question 5

What is the role of carnitine in acyl-CoA transfer

Answer 5

acyl group is transferred to carnitine, carried across the inner mitochondrial membrane, then transferred to mitochondrial CoA

Question 6

true or false; acyl-CoA crosses the outer mitochondrial membrane but not the inner membrane

Answer 6

true

Question 7

What is the enzyme used for the transfer of acyl group to carnitine

Answer 7

carnitine palmitoyltransferase (CPT-1)

Question 8

what has CPT-1 have specificity for

Answer 8

acyl groups between 14 and 18 carbons long

Question 9

where does the breakdown of fatty acids occur

Answer 9

mitochondrial matrix and proceeds by successive removal of 2C as acetyl CoA

Question 10

What do you call the reaction that each 2C moiety must undergo to be converted to acetyl CoA

Answer 10

B-oxidation

Question 11

What is B-oxidation

Answer 11

a series of four reactions that cleaves carbon atoms two at a time from the carboxyl end of the fatty acid

Question 12

What are the 4 central reactions of B oxidation

Answer 12

1. ) dehydrogenation across a-B and C-C bond (-H2O)
2. ) hydration of the same bond (H2O)
3. ) second dehydrogenation yields a B-keto group
4. ) attack by CoASH to form a new, shorter FA-CoA and acetyl CoA

Question 13

What are the saturated FAs with even number chain length

Answer 13

C14, 16, 18 etc

Question 14

true or false; saturated FAs with even number chain length can be completely oxidized by this route B oxidation

Answer 14

true

Question 15

true or false; odd numbered carbon FAs can be metabolized via the B oxidation as well but a 3C unit remains

Answer 15

true

Question 16

what is the 3C unit that remain after B oxidation of an odd numbered fatty acid

Answer 16

propionyl CoA

Question 17

what is propionyl CoA converted to

Answer 17

methylmalonyl CoA by carbon dioxide fixation; this can also enter the TCA cycle via the coversion to succinyl CoA

Question 18

What happens to unsaturated fatty acids

Answer 18

FAs containing a double bond require an additional enzyme for degradation

the cis-enoyl group is converted to the trans configuration by an ISOMERASE

Question 19

true or false; lipid oxidation generates water and CO2

Answer 19

true

Question 20

Why do ketone bodies form

Answer 20

• surplus acetyl CoA cannot be oxidized by the TCA cycle if cellular levels of oxaloacetate are insufficient to react with; instead acetyl CoA is converted to ketone bodies

Question 21

What causes low oxaloacetate

Answer 21

diet high in lipids and low carbs
diabetes not well controlled
starvation

Question 22

what are 2 types of ketone bodies

Answer 22

acetone
B-hydroxybutyrate
acetoacetate

Question 23

where are ketone bodies formed

Answer 23

in liver mitochondria

Question 24

what uses ketone bodies

Answer 24

can be used in most tissue and organ including the brain but only after prolonged starvation

• metabolic state called KETOSIS

Question 25

what is excess carbohydrate stored as

Answer 25

fat

Question 26

true or false; fat is a compact energy storage form, being highly reduced an anhydrous

Answer 26

true

Question 27

What are the major producers of fat

Answer 27

liver and fat cells

- mammary glands also have the ability to synthesize fat during milk production

Question 28

why cant mammals synthesize glucose from fatty acids

Answer 28

because pyruvate dehyrogenase and pyruvate kinase are irreversible

Question 29

how much energy is in 1 g of fat

Answer 29

9 kcal

Question 30

how much energy is in 1g of carbs

Answer 30

3.75kcal

Question 31

how much energy is in 1g of protein

Answer 31

4 kcal

Question 32

What is the symbol for respiratory quotient

Answer 32

RQ

Question 33

Expression of RQ

Answer 33

CO2 generated in mol/ O2 consumed in mol

Question 34

true or false; after digestion is complete the RQ is nearly 1.0

Answer 34

true

- shows that carbs (as liver glycogen) is preferentially oxidized in this state

Question 35

What is the RQ during starvation

Answer 35

0. 71

- fats are preferentially oxidized in the starved state

Question 36

where is the chain lengthening and introduction of double bond for FA metabolism

Answer 36

ER