Biochemistry- Lipid And Fatty Acid Metabolism

Front 1

Describe the structure triacylglycerol. Is triacylglycerol water soluble?

Back 1

Glycerol backbone with 3 acyl chains, There is no phosphate on this molecule and it is not water soluble

Front 2

How is triacylglycerol digested in the intestine?

Back 2

It is emulsified by bile salts, degraded by intestinal lipase, and formed into a mixed micelle.

Front 3

What special processing occurs to digest triacylglycerol and what enzymes are involved in the process?

Back 3

Emulsification by bile salts is done to break down the triacylglycerol into a small particle. Lipoprotein lipase cleaves the acyl chain at the 1 and 3 position.

Front 4

We discussed 3 lipases in class, what are they?

Back 4

intestinal lipase, lipoprotein lipase, and hormone sensitive lipase

Front 5

What does intestinal lipase do? Where is it located in the body?

Back 5

Intestinal lipase breaks down dietary lipid in the intestine

Front 6

What does lipoprotein lipase do, and where is it located in the body?

Back 6

Lipoprotein lipase is on endothelial cell walls and breaks down triacylglycerol in the liproprotein particles in the blood

Front 7

What does hormone sensitive lipase do, and where is it located in the body?

Back 7

Hormone-sensitive lipase is in the adipose cells and breaks down stored triacylglycerol during the fasted state

Front 8

What is a chylomicron? Where is it made and what is its function?

Back 8

A chylomicron is a lipoprotein particle that is synthesized in the intestinal cell to package the dietary lipid that has been digested and absorbed. The chylomicron distributes dietary fat to adipose tissue in the body

Front 9

What is the function of chylomicrons?

Back 9

Chylomicrons distribute dietary fat to adipose tissue

Front 10

What is the function of VLDL (Very Low Density Lipid) Particles?

Back 10

VLDL particle distribute lipid made in the liver to the rest of the body

Front 11

What is the function of LDL (Low Density Lipid) Particles?

Back 11

LDL particles contain cholesterol and deliver it to the rest of the body (Can contain the “bad” cholesterol)

Front 12

What is the function of HDL (High Density Lipid) Particles?

Back 12

HDL particles pick up cholesterol out in the circulation and return it to the liver for excretion

Front 13

What is the rate-limiting step in beta-oxidation of fatty acids?

Back 13

Import of fatty acids into the mitochondrial matrix via the carnitine shuttle

Front 14

In what compartment of the cell does does beta-oxidation take place?

Back 14

Mitochondrial matrix

Front 15

What pathway might be inhibited in a person who has a carnitine deficiency?

Back 15

Beta-oxidation of fatty acids

Front 16

What products are directly made from the beta-oxidation of fatty acids?

Back 16

NADH, FADH2, Acetyl CoA

Front 17

In what tissue and under what physiologic conditions are ketones synthesized?

Back 17

Ketones are made in the liver during the fasted state when rates of beta oxidation are very high and carbohydrate oxidation is limited

Front 18

What is malonyl CoA, and what functions does it have in tissues?

Back 18

Malonyl is the substrate for making new fatty acids (de novo synthesis). This occurs in Liver and Adipose tissue. Malonyl CoA also inhibits the carnitine shuttle, which prevents beta oxidation from occurring at a time when glucose levels are high and glucose can be oxidized for energy.

Front 19

Malonyl CoA is synthesized from acetyl CoA in the cytoplasm. Where does the acetyl CoA come from that is used for making malonyl CoA?

Back 19

Acetyl CoA in the cytosol is made from citrate that came from the inner mitochondrial matrix. The citrate is able to be transported across the inner mitochondrial matrix, but Acetyl CoA and other CoA derivatives cannot pass through this membrane.

Front 20

What is the endproduct of complete functioning of the fatty acid synthase complex?

Back 20

Palmityl CoA is the direct endproduct of this pathway.

Front 21

What are the names and structures of the two essential dietary fatty acids?

Back 21

1) Linoleic acid, an 18 carbon fatty acid with 2 double bonds, 2) Linolenic acid, an 18 carbon fatty acid with 3 double bonds

Front 22

What are dietarily essential fatty acids used for?

Back 22

They are used to synthesize the 20 carbon fatty acid (arachidonic acid, in the case of Linoleic), that is then used to synthesize prostaglandins, Thromboxanes, and leukotrienes

Front 23

What role do products of the cyclooxygenase pathway perform in the body?

Back 23

The cyclooxygenase pathway synthesizes prostaglandins and thromboxanes which regulated many cellular functions including inflammation and pain

Front 24

What role do products of the lipoxygenase pathway perform in the body?

Back 24

The leukotrienes that are made by the lipoxygenase pathway cause asthma

Front 25

How is cholesterol synthesized (i.e., the rate-limiting step)?

Back 25

The formation of mevalonate via the enzyme HMG CoA reductase

Front 26

How is cholesterol eliminated from the body?

Back 26

Cholesterol is eliminated from the body by fecal excretion of Bile salts

Front 27

How do cholesterol-lowering drugs work?

Back 27

By inhibiting HMG-CoA reductase to inhibit cellular synthesis of cholesterol

Front 28

When we are in the fasted state, which of our internal organs is responsible for secreting glucose, and what pathways allow this to happen?

Back 28

The liver secretes glucose in the fasted state, this is derived from glycogenolysis and gluconeogenesis

Front 29

Under what physiologic conditions are free fatty acids released from the adipose tissue, and what enzyme is responsible for the release?

Back 29

The free fatty acids are released by adipose tissue during fasting when insulin levels are low. The free fatty acids are released by the activity of the hormone sensitive lipase.

Front 30

What are the major metabolic pathways activated in the liver in the FED state for metabolizing carbohydrates?

Back 30

Carbohydrate is being oxidized by glycolysis, being made into glycogen, or being made into new fatty acids.

Front 31

What are the major metabolic pathways activated in the liver in the FED state for metabolizing lipids?

Back 31

Lipids are being packaged into VLDL particles for excretion

Front 32

What are the major metabolic pathways activated in the liver in the FED state for metabolizing amino acids?

Back 32

Amino acids are being used for new protein synthesis, or being deaminated and being used like carbohydrates.

Front 33

What are the major metabolic pathways activated in the liver in the FASTED state for metabolizing carbohydrates?

Back 33

The liver is synthesizing glucose by gluconeogenesis or glycogenolysis.

Front 34

What are the major metabolic pathways activated in the liver in the FASTED state for metabolizing lipids?

Back 34

Lipids are being oxidized by beta-oxidation and making ketones.

Front 35

What are the major metabolic pathways activated in the liver in the FASTED state for metabolizing amino acids?

Back 35

Amino acids are being deaminated and used for gluconeogenesis.

Front 36

What is the function of insulin and glucagon in regulating metabolism?

Back 36

Insulin is the hormone to promote storage of nutrients and protein synthesis. Glucagon regulates fasting metabolism and stimulates gluconeogenesis and glycogenolysis to promote glucose secretion by the liver.

Front 37

Where are ketones made, and why are they useful in the body?

Back 37

Ketones are synthesized in the liver, they are useful because they can be sent out into the circulation to be used by other tissues as an energy source during the fasted state.

Front 38

HDL (High Density Lipid) Particles are associated with which 2 apoliliproteins. What are they?

Back 38

1. ApoA-I (function is to activate LCAT. Also interacts with ABC Transporter) 2.ApoA-II

Front 39

Chylomicrons are associated with what apolipoprotein?

Back 39

ApoB-48

Front 40

VLDL and LDL are associated with what apolipoprotein?

Back 40

ApoB-100 (function is to bind to LDL receptor)