FOM 3.1.2 Flashcards

1
Q

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

A

NADH and FADH2

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2
Q

Beta oxidation converts fatty acids into?

A

Acetyl CoA

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3
Q

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

A

Triacylglycerols, glycerophospholipids, and free FAs

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4
Q

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

A

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

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5
Q

Is this fatty acid cis or trans?

A

It is Cis

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6
Q

How are most fatty acids in nature arranged?

A

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

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7
Q

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

A

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

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8
Q

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

A

White adipose tissue

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9
Q

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

A

Fats!

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10
Q

Fatty acids are catabolized by what cellular compartment?

A

Mitochondrial matrix

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11
Q

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

A

Fatty acyl CoA

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12
Q

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

A

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

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13
Q

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

A

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

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14
Q

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

A

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

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15
Q

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

A

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

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16
Q

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

A

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.

17
Q

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

A

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.

18
Q

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

A

These carry out redox reactions

19
Q

How do cells deal with differing length of FA chains?

A

Different isozymes account for the differing sizes of FAs.

20
Q

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?

A

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

21
Q

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

A

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

22
Q

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?

A

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.

23
Q

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

A

Oxidation must be occuring somewhere else

24
Q

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

A

FA-9

Prot-4

Carbs-4

25
Q

Catabolism is said to be what?

What is anabolism said to be?

A

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.

26
Q

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

A

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.

27
Q

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

A

The TCA cycle

28
Q

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

A

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

29
Q

What is the fate of an odd chain fatty acid?

A

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.

30
Q

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

A

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.

31
Q

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

A

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

32
Q
A