FOM 3.1.2

Question 1

What molecules carry electrons released in the beta-oxidation pathway?

Answer 1

NADH and FADH2

Question 2

Beta oxidation converts fatty acids into?

Answer 2

Acetyl CoA

Question 3

Three macromolecules from diet that can be a source of fatty acids are?

Answer 3

Triacylglycerols, glycerophospholipids, and free FAs

Question 4

What two fatty acids are required in the diet? And how are these numerically designated?

Answer 4

Omega 3 and Omega 6 fatty acids

They are counted from the omega end and wherever the double bond is that is where is designated

Question 5

Is this fatty acid cis or trans?

Answer 5

It is Cis

Question 6

How are most fatty acids in nature arranged?

Answer 6

Fatty acids tend to be unbranced in nature and have an even number of carbon groups

Question 7

Do cis or trans fatty acids tend to be favored in a diet and why?

Answer 7

The cis form is favored in almost all unsaturated fats occuring in nature. Trans-fats only began to be used once in the food industry.

Side note: it is thought that the cis unsaturated bonds are not able to pack as tightly hence

Question 8

What specific type of adipose tissue serves as a store for long-chain fatty acids?

Answer 8

White adipose tissue

Question 9

At rest most other tissues other than the brain prefer to use what as an energy source?

Answer 9

Fats!

Question 10

Fatty acids are catabolized by what cellular compartment?

Answer 10

Mitochondrial matrix

Question 11

What is a fatty acid first converted into before being catabolized?

Answer 11

Fatty acyl CoA

Question 12

How many ATP equivalents are used in “activation” of the fatty acids?

Answer 12

The first step is to take the free fatty acid have it undergo a reaction carried out by Acyl-CoA synthetase. This then creates AMP and Acyl-CoA. The ATP is utilized twice (ATP –>ADP and ADP –> AMP) and thus utilized two equivalents of ATP

Question 13

How is the acyl-CoA transported from the cytosol to the mitochondria?

Answer 13

It is transferred by a carnitine carrier protein. Carnitine reacts with the acyl-CoA on the cytosolic side yielding acyl-carnitine. It then transverses the inner mitochondrial membrane and reacts with H-SCoA, yielding acyl-CoA in the mitochondrial matrix

Question 14

What is the regulatory mechanism that cells use to prevent energy waste during synthesis and catabolism?

Answer 14

The cells use compartmentalization. Catabolism is occurring in the matrix and synthesis is occurring in the cytosol

Question 15

What is the process by which FA transfer into the mitochondria is regulated?

Answer 15

This first step in regulating the transfer of FA entry into the mitochondria is the conversion of Acetyl-CoA to Malonyl-CoA by the enzyme Acetyl-CoA carboxylase. Malonyl-CoA will then go and turn off the transfer of carnitine transferase so that acyl-CoA will stay in the cytosol

Question 16

What will happen to the transfer of fatty acids to the mitochondria in a scenario with high glucose?

Answer 16

High levels of glucose will lead to the creation of malonyl-CoA, which will then shut off the carnitine transporter and acyl-CoA is not transferred to the mitochondrial matrix.

Question 17

What happens to the transport of FAs into the mitochondria during a period of high fat?

Answer 17

There is not enough sugar to create malonyl-CoA, thus it is not created and does not inhibit carnitine transferase. Acyl-CoA is tranported into the mitochondria.

Question 18

What are the type of chemical reactions that are carried out by NADH and FADH2 in beta-oxidation?

Answer 18

These carry out redox reactions

Question 19

How do cells deal with differing length of FA chains?

Answer 19

Different isozymes account for the differing sizes of FAs.

Question 20

After one round of Beta-oxidation the cell is left with one acetyl-CoA and one Fatty acyl-CoA. What is the fate of the fatty acyl-CoA?

Answer 20

It is brought right back to the beginning to go through another round of beta-oxidation.

Question 21

What is the process of dealing with an unsaturated fatty acid with an unsaturation between the alpha and beta bonds?

Answer 21

No change is needed to deal with this. There is just no FADH2 created during the first step of oxidation.

Question 22

What is the process by which a cell deals with a fatty acid that has an unsaturation on the other side of the beta-carbon?

Answer 22

These go through a modified first step and Enoyl-CoA isomerase moves the double bond between the alpha and beta carbon. This still does not produce any FADH2 because there is no needed oxidation step.

Question 23

If one molecule is reduced in a redox reaction the what must happen somewhere else?

Answer 23

Oxidation must be occuring somewhere else

Question 24

What are the amount of calories from FAs, proteins, and carbs?

Answer 24

FA-9

Prot-4

Carbs-4

Question 25

Catabolism is said to be what? What is anabolism said to be?

Answer 25

Catabolism - said to be oxidative, substrates lose reducing equivalents, usually H- ions. Anabolism - said to be reductive, NADPH provides the reducing powers for the building process.

Question 26

What is the mechanism by which acetyl-CoA is transported out of the mitochondria?

Answer 26

Acetyl-CoA reacts with citrate synthase yielding citrate. This citrate is transported out by the tricarboxylate system. The cytosol then usus this citrate for various things.

Question 27

Where is another place that the acetyl-CoA from beta-oxidation can be used?

Answer 27

The TCA cycle

Question 28

What are possible fates for the co-factors used in beta-oxidation?

Answer 28

FADH2 and NADH can use the electrons they took from here and use them in the electron transport chain.

Question 29

What is the fate of an odd chain fatty acid?

Answer 29

After all the possible rounds of beta-oxidation, the cell will be left with propionyl-CoA. This will be converted into succinyl-CoA and used in the citric acid cycle.

Question 30

During periods of starvation what does the brain use for energy as an alternative source?

Answer 30

In the liver, Acyl-CoA is converted into ketone bodies (acetoacetate and 3-hydroxybutyrate). These are then used for energy in the brain as well as the kidneys and muscle.

Question 31

How many ATP are yielded from one 16 carbon chain FA?

Answer 31

The FA will go through 7 rounds of beta-oxidation. Which will result in the generation of 8 acetyl CoA units. It will also generate 7 NADH and 7FADH2. 12 x 8 =96 (Acetyl CoA) 7 x 3 = 21 (NADH) 7 x 2 = 14 (FADH2) 131 - 2 (For the first step in "activation") = 129 Total ATP