Beta Oxidation: Revision session topics

Question 1

What is the first step in Beta oxidation?

Answer 1

Acyl Coa is converted into trans-double bond- 2-enoyl CoA

Question 2

How is Acyl-CoA converted into trans-double bond- 2-enoyl CoA?

Answer 2

Long chain fatty acid dehydrogenated (trans double bond between C2 and C3) = trans-double bond 2-enoyl CoA

(catalysed by dehydrogenase I).

FAD = Electron acceptor - reduced to FADH2

Question 3

What catalyses the first step in Beta-oxidation?

Answer 3

Dehydrogenase I

Question 4

In the first step of beta oxidation, what is the process of dehydrogenation?

Answer 4

FAD = electron acceptor which is reduced to FADH2

Question 5

What is the second step in Beta oxidation?

Answer 5

trans-double bond 2-enoyl CoA is converted into L-3-or Beta Hydroxyacyl CoA

Question 6

In the second step in Beta oxidation, how is trans-double bond 2-enoyl CoA converted to L-3-or Beta Hydroxyacyl CoA?

Answer 6

trans-double bond 2-enoyl CoA- hydrated at double bond = L-3-or Beta Hydroxyacyl CoA

+H2O

Question 7

What catalyses step 2?

multiple headed snake

Answer 7

Catalysed by hydratase

Question 8

What is the third step in Beta oxidation?

Answer 8

L-3-or Beta Hydroxyacyl CoA converted to Beta-Ketoacyl CoA

Question 9

In the third step in Beta oxidation how is L-3-or Beta Hydroxyacyl CoA converted to Beta-Ketoacyl CoA?

Answer 9

L-3-or Beta Hydroxyacyl CoA is dehydrogenated again to make Beta-Ketoacyl CoA

NAD = Electron acceptor - reduced to NADH

Question 10

What catalysis step 3?

Answer 10

Dehydrogenase II

Question 11

What is the Forth step in Beta oxidation?

Answer 11

Beta-Ketoacyl CoA is broken into Fatty acyl CoA and Acetyl CoA.

Question 12

In the fourth step for beta oxidation, how is Beta-Ketoacyl CoA broken down to Fatty acyl CoA and Acetyl CoA

Answer 12

Thiolase breaks bond between C3 and C2 (beta and alpha carbons) by attaching new CoA onto C3.

This releases the first two carbon (C1 and C2) units, as acetyl CoA, and a 2C shorter fatty acyl CoA where the new C1 is the old BetaC or C3)

Question 13

What happens to Acetyl CoA at the end of Beta oxidation?

Answer 13

Transports to the TCA cycle

Question 14

What happens to Fatty acyl CoA at the end of Beta oxidation?

Answer 14

Fatty acyl CoA is recycled back to the start of the beta oxidation cycle

Question 15

Summerise the process of Beta oxidation

Answer 15

Beta-Oxidation takes place via successive repetition of a four-step cycle. Each cycle shortens the fatty acid chain by two carbon atoms and generates one molecule each of reduced FADH2, NADH and an acetyl-CoA. These molecules can in turn be metabolised to produce ATP (acetyl-CoA in the citric acid cycle and FADH2 and NADH in the electron transport system)

Question 16

Summerise the end products of beta oxidation

Answer 16

The end product of each cycle is the fatty acid shortened by 2 carbons and acetyl CoA. The series of reactions is also known as the beta-oxidation pathway because the major reaction site is the beta-carbon or #3 carbon from the thioester carbon