Beta oxidation

Question 1

How are fatty acids digested?

Answer 1

1. Emulsification by bile salts
2. Degraded by lipases
3. Converted to triacylglycerols
4. Packaged into chylomicrons for transport
5. Travel to target tissues

Question 2

In what cases or places is degradation of fats used as a major source of energy?

Answer 2

Heart muscle

Resting skeletal muscle

Liver

Hibernating animals

Question 3

The products of triacylglycerol hydrolysis are glycerols, which can enter _________________ or ________________, and fatty acids, which can enter ____ _______________.

Answer 3

Glycolysis

Gluconeogenesis

Beta oxidation

Question 4

Fats are mobilized from lipid dropets through a _________________ ________________ in the adipocyte.

Answer 4

Signaling pathway

Question 5

Lipid droplets contain _______________ ____________, mostly triacylglyerols, and ____________, proteins on the surface of lipid droplets that restrict access to the inner core.

Answer 5

Cholesterol esters

Perilipin

Question 6

Do lipid droplets have a mono- or bilayer of phospholipids?

Answer 6

A monolayer

Question 7

Glucagon and epinephrine in the adipocyte signal the activation of PKA. Regarding fatty acid degradation, PKA phosphorylates and activates ____________, which allows for lipase access to triacylglycerols in lipid droplets, and ____________ ___________ ____________, which hydrolyze triacylglyerols into three fatty acids and glycerol.

Answer 7

Perilipin

Hormone sensitive lipases

Question 8

“Free” fatty acids are carried non-covalently through the blood stream by serum _______________ and transported to target sells.

Answer 8

Albumin

Question 9

Where are fatty acids oxidized?

Answer 9

Mitochondrial matrix

Question 10

What is the first reaction in fatty acid oxidation?

Answer 10

Fatty acyl-CoA synthetase

Question 11

What is the mechanism of fatty acyl-CoA synthetase?

Answer 11

Ampylation

Question 12

What intermediate is produced in the fatty acyl-CoA synthetase mechanism?

Answer 12

Fatty acyl-AMP

Question 13

How does AMP leave the fatty acyl molecule?

Answer 13

After nucleophilic attack by CoASH

Question 14

What is the end product of fatty acyl-CoA synthetase?

Answer 14

Fatty acyl-CoA

Question 15

Where does fatty acyl-CoA synthesis occur?

Answer 15

Cytosol

Question 16

Where is fatty acyl-CoA synthetase located?

Answer 16

Outer mitochondrial membrane

Question 17

How many ATPs does fatty acyl-CoA synthetase require?

Answer 17

2 ATPs

Question 18

How does fatty acyl-CoA enter the intermembrane space?

Answer 18

Via the fatty acyl-CoA porin

Question 19

What happens to fatty acyl-CoA once in the intermembrane space?

Answer 19

It is converted to fatty acylcarnitine via the carnitine-palmitoyl transferase I

Question 20

Fatty acyl CoA and ______________ are converted to CoA and _________ ____________ via carnitine palmitoyl transferase I in the intermembrane space.

Answer 20

Carnitine

Fatty acylcarnitine

Question 21

How does fatty acylcarnitine enter the mitochondrial matrix?

Answer 21

Via the carintine acylcartine translocase

Question 22

The carnitine acylcarnitine translocase is an _____________________, bringing fatty acylcarnitine into the mitochondrial matrix while transporting out of the mitochondrial matrix.

Answer 22

Antiporter

Question 23

The carnitine acylcarnitine translocase is a type of ______________ based on concentration gradients.

Answer 23

Passive transport

Question 24

What happens to fatty acylcarnitine once it enters the mitochondrial matrix?

Answer 24

It is converted to fatty acyl-CoA via carnitine-palmitoyl transferase II

Question 25

Fatty acylcarnitine and CoA are substrates for _________________ \_\_\_\_\_\_\_\_\_\_\_\_\_ ____________ \_\_\_\_, which converts these products to fatty acyl-CoA, for beta oxidation, and carnitine, which is transported back into the intermembrane space via the carnitine acylcarnitine translocase.

Answer 25

Carnitine pamitoyl transferase II

Question 26

What are the enzymes and porins/antiporters involved in the carnitine shuttle system?

Answer 26

Fatty acyl-CoA synthetase Fatty acyl-CoA porin Carnitine-palmitoyl transferase I Carintine acylcarintine translocase Carnitine-pamitoyl transferase II

Question 27

What is the rate-limiting step in the oxidation pathway?

Answer 27

Entry of fatty acids into the mitochondria

Question 28

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ _______________ is an inhibitor of the carnitine palmitoyl transferase I.

Answer 28

Malonyl CoA

Question 29

Complete oxidation of fatty acids occurs in three stages. What are they?

Answer 29

1. Beta-oxidation 2. Acetyl-CoA oxidation to CO2 in CAC 3. Electron transport and oxidation

Question 30

Beta-oxidation occurs in four steps. What are they?

Answer 30

1. Dehydrogenation of fatty acyl-CoA via acyl-CoA **dehydrogenase** 2. Hydration of double bond of trans-delta2-enoyl-CoA catalyzed by enoly-CoA **hydratase** 3. Beta-hydroxylacyl-CoA dehydrogenated to form beta-ketoacyl-CoA catalyzed by beta-hydroxyacyl-CoA **dehydrogenase** 4. Reaction of beta-ketoacyl-CoA with CoA to give off acetyl-CoA catalyzed by **thiolase**

Question 31

Acyl-CoA dehydrogenase forms a trans double bond at the ___ position via reduction of \_\_\_\_.

Answer 31

Alpha position FAD

Question 32

Enoyl-CoA hydratase adds a water molecule across the trans double bond with the hydroxyl group positioned at the ___ position.

Answer 32

Beta

Question 33

Beta-hydroxylacyl-CoA dehydrogenase oxidizes the hydroxyl group to a ketone via reduction of \_\_\_\_.

Answer 33

NAD+

Question 34

Beta-ketoacyl-CoA reacts with CoA to give off CoASH via ______________ in the last step of beta oxidation.

Answer 34

Thiolase

Question 35

What is the net yield of one round of beta oxidation?

Answer 35

1 FADH2 1 NADH 1 acetyl-CoA

Question 36

What is MCAD deficiency?

Answer 36

An autosomal-recessive disorder that reduces an individual's ability to oxidize fatty acids with 6 to 10 carbons resulting in severe hypoglycemia and hypoketonemia; treatment is to avoid fasting

Question 37

What happens when a fatty acid contains a cis double bond? What is required to bypass this?

Answer 37

A general base deprotonates the alpha position and creates an oxyanion An isomerase catalyzes the restoration of the carbonyl group, which shifts the trans double bond over one and causes the cis double bond to protonate

Question 38

What enzyme catalyzes the conversion of a cis or trans double bond at position 3 to a trans double bond at position 2.

Answer 38

Enoly-CoA isomerase

Question 39

A cis delta-4 double bond inhibits enoly-CoA hydratase. What reduces the delta-4 double bond?

Answer 39

2,4-dienoyl-CoA reductase