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Biochemistry > Lipid Metabolism > Flashcards

Lipid Metabolism Flashcards

1
Q

The digestion of lipids is dependent on what?

A

The length of fatty acids in the TAG.

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2
Q

You encounter a patient who has low levels of bile production. How will their ability to eat fatty foods be altered?

A

They will have a decreased tolerance to fatty foods since there is not enough bile to emulsify the fat.

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3
Q

You encounter a patient who has a deficiency in the gut hormone cholecystokinin. Do you expect the patient to have a high or low tolerance for fatty foods?

A

Low tolerance; cholecystokinin is what allows for the release of bile, which subsequently emulsifies fats.

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4
Q

What is the purpose of emulsification?

A

To increase the surface area of fats for digestion.

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5
Q

How will the activity of pancreatic lipase be affected if short chain fatty acids are present versus long chain fatty acids?

A

The activity will remain unchanged. Pancreatic lipase can digest fatty acids of any length.

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6
Q

Pancreatic lipase is important for the regulation of pH in the small intestine. What does pancreatic lipase release in order to increase pH?

A

bicarbonate.

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7
Q

What is the function of esterase, and what organ produces it?

A

To remove fatty acids from cholestrol esters; the pancreas.

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8
Q

How are dietary lipids absorbed?

A

By intestinal epithelial cells.

They subsequently enter the blood and are transported into the liver.

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9
Q

Long chain fatty acids are in what conformation when they are emulsified?

A

micelles.

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10
Q

After fatty acids are reabsorbed, how does their structure change?

A

They are condensed to form TAGs.

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11
Q

What are chylomicrons?

A

Vessels that TAGs are packaged into after they have been re-synthesized in the intestinal cells.

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12
Q

Any time a fatty acid enters a reaction, it needs to be ____

A

Primed; this is done by a CoA molecule.

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13
Q

Once triacylglycerides have been re-formed after absorption and packaged into chylomicrons, where do they travel?

A

To the lymph system and the blood.

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14
Q

How do chylomicrons become mature?

A

They accept proteins from HDL within lymph and blood.

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15
Q

What is the function of ApoCII?

A

To digest chylomicrons.

They are present on capillary endothelial cells in muscle and adipose tissue.

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16
Q

What is the function of ApoE?

A

It allows for endocytosis of vesicles in the liver.

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17
Q

True or false: chylomicrons can pass through the plasma membrane.

A

False

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18
Q

You are studying a mouse that has a deficiency in the enzyme lipoproteinlipase. How does this affect the transport of chylomicrons?

A

The transport is not affected, but the chylomicrons will be unable to release fatty acids into adipocytes.

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19
Q

What are the 3 necessary steps to use fatty acids as fuel?

A

mobilization, activation and degradation.

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20
Q

What occurs in fatty acid mobilization?

A

TAGs in adipose tissue are broken to FA and glycerol, released and transported to energy-requiring tissue.

21
Q

What occurs during fatty acid activation?

A

Fatty acids must be activated and transported into mitochondria.

22
Q

What occurs during degradation?

A

Stepwise breakdown of FA into acetyla CoA which is then processed in TCA cycle.

23
Q

During fasting and exercise, what activates the mobilization of fatty acids from adipocytes?

A

glucagon and epinephrine.

24
Q

What is the function of perilipin?

A

It guards the fats as they are being mobilized.

25
Q

In the mobilization of fatty acids from adipocytes, how are perilipin and HS lipase inactivated?

A

via phosphorylation

26
Q

What is triacylglycerol broken down into during lipolysis?

A

glycerol and fatty acids.

27
Q

The glycerol from lipolysis can be used for what two processes in the liver?

A

pyruvate and glucose

28
Q

Fatty acids from lipolysis can be used in what cycle?

A

TCA

29
Q

Where is glycerol kinae ONLY found?

A

The liver.

30
Q

What is glycerol eventually broken down into in the liver?

A

Glyceraldehyde-3-phosphate.

31
Q

Where does fatty acid activation occur?

A

In the cytosol.

32
Q

What is the function of the carnitine shuttle?

A

It carries long-chain fatty acly CoAs across the mitochondrial membranes.

33
Q

Where does beta oxidation primarily occur?

A

in the mitochondrial matrix.

34
Q

What is the role of carnitine?

A

It makes acyl carnitine from acetyl CoA and carnitine.

35
Q

Where are all of the enzymes of beta oxidation found?

A

In the mitochondrial matrix.

36
Q

What is the first step of fatty acid oxidation?

A

The conversion of acyl CoA to trans=enoyl CoA.

This is done via acyl CoA dehydrogenase.

37
Q

What is the second step of fatty acid oxidation?

A

The conversion of trans-enoyl CoA to hydroxyacyl CoA. This is done via enoyl CoA hydrase.

38
Q

What is the third step in beta oxidation?

A

The conversion of hydroxyacyl oA to ktoacyl CoA. This is done via hydroxy Acyl CoA dehydrogenase.

39
Q

What is the final step in beta oxidation?

A

Conversion of 3-ketoacyl CoA to acyl CoA and acetyl CoA.

40
Q

How many molecules of ATP does each acetyl CoA molecule make?

A

10

41
Q

What enzyme degrades fatty acids with odd-numbered double bonds?

A

isomerase.

42
Q

What enzymes degrade fatty acids with even numbers of double bonds?

A

reductase and isomerase.

They are converted from propionyl CoA to succinyl CoA, which then enters TCA.

43
Q

What enzyme degrades monounsaturated fatty acids?

A

enoyl CoA isomerase

44
Q

The acetyl CoA produced from the degradation of fatty acids combines with oxaloacetate to form what molecule?

A

Citrate.

45
Q

In fasting or diabetes, what does acetyl CoA become?

A

Ketone bodies (acetoacetate, acetone, hydroxybutryate).

46
Q

Acetoacetate can be converted into what molecule?

A

Acetyl CoA.

47
Q

You encounter a diabetic patient who is in a diabetic coma. A blood test reveals that they have a decreased blood pH. This is a result of the presence of what molecule?

A

ketone bodies.

48
Q

When you drink milk (composed of short and medium fatty acid chains), where will it be digested, and what enzymes are responsible for this?

A

Lingual (tongue) and gastric (stomach) lipases.

Biochemistry (13 decks)

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