Fatty Acid Metabolism Q6

Question 1

Out line exogenous process of dietary lipids entering body and transportation.

Answer 1

Bile salts emulsify in small intestine, lipases degrade triacylglycerols, fatty acids taken up in intestinal mucosa and converted into triacylglycerols, formation of chylomicrons which move through lymph and bloodstream, lipase converts triacylglycerols to fatty acids, fatty acids oxidized for fuel.

Question 2

What are the two “structures” that fats are able to move through your system? Explain them.

Answer 2

Either carried by serum albumin if they are free fatty acids which binds several fatty acids and carries through vasculature. Or through production of lipoproteins IE chylomicron. Proteins with monolayer, cholesterol, and associated apolipoproteins.

Question 3

What are the 4 types of lipoproteins?

Answer 3

Chylomicrons, Very low density lipoprotein (VLDL), Low density lipoprotein (LDL), High density lipoprotein (HDL).

Question 4

What are the two pathways used to transport lipoproteins?

Answer 4

Exogenous pathway: Formation of chylomicrons (from diet). Endogenous pathway: Occurs in the liver. Uses lipoproteins. IE creates VLDLs.

Question 5

What are the fates of lipids and fatty acids?

Answer 5

Energy substrates, precursors, structural elements, signaling molecules.

Question 6

What is the difference between fatty acids and lipids?

Answer 6

Fatty acids are carboxylic acids with long carbon chains. Lipids have one or more fatty acids connected by linker molecule IE phosphate group.

Question 7

Which two proteins transport cholesterol?

Answer 7

LDL and HDL.

Question 8

How are fatty acids mobilized from adipose?

Answer 8

Pancreas releases glucagon which interacts with receptor on adipose tissue causing cAMP to activate protein kinase A. PKA phosphorylates perilipin located in lipid droplets. CGI is released and phosphorylates adipose triglyceride lipase (ATGL) which then breaks down triglycerides. PKA causes HSL converts to monoglycerides and MGL then removes glycerol molecule.

Question 9

Where will glycerol go once it is removed from the triglyceride?

Answer 9

It will move into glycolysis.

Question 10

What will happen to the fatty acid once removed from the triglyceride by lipase?

Answer 10

It will be turned into fatty acyl-CoA.

Question 11

Where does the break down of triglycerides take place?

Answer 11

Cytoplasm of the cell. This is why they need to be transported into the mitochondrial matrix for oxidation.

Question 12

How is Fatty Acyl-CoA transported to matrix?

Answer 12

Via acyl-carnitine transporter. At the outer membrane, fatty acyl is transferred to carnitine which then is transported in as a carnitine is transported out. Then the fatty acyl is transferred to a CoA molecule in matrix via carnitine acyltransferase II.

Question 13

What are the three stages of fatty acid oxidation?

Answer 13

1- beta oxidation by breaking down chain into two carbon sections and also create NADH and FADH2 . 2-The two carbons are used to create acetyl-CoA molecules also producing NADH and FADH2. 3- The NADH and FADH@ created is then used in ETC.

Question 14

How much ATP will be produced from palmitate?

Answer 14

108 ATP

Question 15

What will happen to odd carbons and unsaturated fatty acids in beta oxidation?

Answer 15

They will undergo additional steps to oxidize.

Question 16

What is the function of acyl-CoA dehydrogenase?

Answer 16

It is a component of the ETC and where beta oxidation feeds directly into the ETC through production of FADH2 and NADH.

Question 17

What are the three things that can happen with acetyl-CoA produced in the liver?

Answer 17

1- It can enter the CAC to produce energy. 2- It can create oxaloacetate for gluconeogenesis. 3- Or when the gluconeogenesis pathway becomes saturated, you can form ketone bodies.

Question 18

What are ketone bodies formed from?

Answer 18

Acetyl-CoA.

Question 19

What are the three ketone bodies?

Answer 19

Acetoacetate, Acetone, and D-b-Hydroxybutyrate.

Question 20

What are the two major sources for the formation of fatty acids?

Answer 20

Dietary carbs and proteins.

Question 21

What molecule will drive formation of excess acetyl-CoA into triglycerides?

Answer 21

Insulin.

Question 22

How is polmitoyl-CoA formed?

Answer 22

Turning Acetyl-CoA into malonyl-CoA and combining that with an acetyl-CoA.

Question 23

Where does lipid synthesis occur?

Answer 23

In the cytoplasmic space. For this reason acetyl-CoA have to be transported into the cytoplasm.

Question 24

What is the enzyme responsible for fatty acid synthesis?

Answer 24

Fatty acid synthase.

Question 25

What is the process of fatty acid synthesis?

Answer 25

acetyl-CoA transported into cytoplasm. Carboxylated into malonyl-CoA. Fatty acid synthase combine Acetyl-CoA and malonyl-CoA to start acyl chain. Fatty aid synthase adds malonyl-CoA carbons to create palmitate. Modification happens at the ER.

Question 26

How does Acetyl-CoA get from the matrix into the cytoplasm?

Answer 26

Via the citrate shuttle. Acetyl-CoA adds Acetyl group to oxaloacetate to form citrate. Citrate then donates it to Co-enzyme A in the matrix. Citrate then forms malate which can then form pyruvate, creating NADPH in the process important for acyl chains.

Question 27

How is acetyl-CoA turned into malonyl-CoA? What factor is required for this?

Answer 27

Via Acetyl-CoA carboxylase. Biotin is acquired from diet via vitamin B7.

Question 28

What are the two types of fatty acid synthase?

Answer 28

FAS I- vertebrates and fungi, only creates 16 chain carbons. FSA II- bacteria and plants.

Question 29

What is the function of acyl carrier protein? What is a vital component of it?

Answer 29

Shuttles malonyl-CoA to the fatty acid synthase. Vital component if pantothenic acid (vitamin B5)

Question 30

What is the initiation of fatty acid synthesis?

Answer 30

Acetyl-CoA donating acetyl (forms omega carbon) group to attach to the end of malonyl group. Then malonyl groups are continually added.

Question 31

Does the forming fatty acid chain become reduced?

Answer 31

Via NADPH donating hydrogen.

Question 32

In the ER what can the fatty acid chain be elongated to?

Answer 32

Stearate which is 18 carbons.

Question 33

What is responsible for regulating fatty acid synthesis?

Answer 33

Acetyl-CoA carboxylase. When there is high blood glucose, glycolysis produces acetyl-CoA which can then be formed in to malonyl-CoA by Acetyl-CoA carboxylase driving fatty acid synthesis. Insulin will activate and glucagon will phosphorylate and deactivate.

Question 34

How is phosphatidic acid formed? Why is it important?

Answer 34

Combination of glucose and glycerol. Head groups and fatty acids can then be added to form other molecules like triglycerides and phospholipids.

Question 35

How is cholesterol formed?

Answer 35

Excess acetate is converted into mevalonate which creates isoprene and formation of cholesterol. Takes place largely in the liver.

Question 36

What are some derivatives of cholesterol?

Answer 36

Bile acids, hormones.

Question 37

How does plaque form?

Answer 37

Macrophage ingesting lipoproteins undergoes apoptosis in the artery and sticks to artery wall.