L22- Fatty acid metabolism Flashcards

1
Q

What are the major forms of stored energy in vertebrates?

A

Triacylglycerols and glycogen

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2
Q

How long can glycogen and TGs supply for?

A

Glycogen- supply energy for less than an hour

sustained work is fueled by metabolism of TGs

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3
Q

Where does the digestion of dietary lipids happen?

A

Small intestine

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4
Q

What produces bile and what does it do?

A

The liver. Bile emulsifies fats

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5
Q

What are lipids absorbed as?

A

In the intestine converted to fatty acylCoA and then triacylglycerols. (TGs)

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6
Q

How are fats transported in the blood stream?

A

In the form of cholymicrons :

TG and cholesterol and specific proteins

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7
Q

What does the beta oxidation pathway do and where?

A

Degrades fatty acids two carbons at a time. takes place in the mitochondria.

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8
Q

What are the 3 stages of beta oxidation pathway?

A
  1. activation of fatty acids in the cytosol
  2. transport into the mitochondria
  3. degradation to two-carbon fragments (as acetyl coA)
    in the mitochondria matrix
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9
Q

In the 2nd step-transport of fatty acel coA into mitochondia, how does it get in?

A

Using carrier molecule-carnitine.
fatty acid had been activated, joined to coA
Transferred to carnitine. makes acyl carnitine. Goes into mitochondria thourhg the translocase. Then carnitine drops off the fatty acid to CoA again.

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10
Q

Each round of beta oxidation makes what?

A

QH2
NADH
Acetyl CoA
Fatty acyl CoA (2 carbons shorter each round)

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11
Q

What is the net yield of ATP per palmitate oxidizes to 16 CO2?

A

its a 16 carbon fatty acid chian. makes 106 atp

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12
Q

Where and when does fatty acid synthesis occur?

A

Mainly in the liver and adipocytes- in the cytosol.

When glucose is plentiful, excess CoA is made in glycolysis, use for fatty acid synthesis.

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13
Q

Where does NADPH come from for FA synthesis?

A

Glucose oxidation in the pentose phosphate pathway

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14
Q

What does acetyl CoA carboxylase do?

A

Catalyzes the formation of malonyl CoA from acetyl CoA. (adds one carbon)
Then 2 carbons from malonyl coA are added to the growing fatty acid chain.
2 carbons at a time

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15
Q

For fuel how are lipids transported?

A

liproproteins (eg LDLs)

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16
Q

What happens to FAs in fed state?

A

FAs stored in adipose tissue.
Insulin levels high- stimulates AcetylCoA carboxylase.
Increases FA synthesis.

17
Q

What happens to FAs in fasting state?

A

Adrenaline stimulates FA mobilisation. Glucagon levels high and inhibit ACC. Shut down FA synthesis.