Lecture 32 - Lipid Metabolism I

Question 1

Lingual and gastric lipases digest _____fatty acids.

a. long chain (> 12 C)
b. short chain (

Answer 1

b. short chain

Question 2

Emulsification of fats occurs by suspension within ______.

a. cholymicrons
b. bile salts

Answer 2

b. bile salts

Question 3

Which of the following is responsible for contraction of the gallbladder?

a. bile releasing enzyme
b. renin
c. secretin
d. cholecystokinin

Answer 3

d. cholecystokinin

(chole-gallbladder; cysto-bladder (the gallbladder is a pouch; kinin-think “kinetic”, it moves the gallbladder to secrete bile)

Question 4

T/F: After emulsification, the bile salt/FA mixture becomes the substrate of pancreatic lipases?

Answer 4

True

Question 5

What hormone stimulates the release of bicarbonate to neutralize the acidic pH of bile salts?

Answer 5

secretin

Question 6

True/False: pancreatic lipase is specific for short chain fatty acids.

Answer 6

False. Pancreatic lipase digests all lengths of FAs

Question 7

2-Monoacylglycerol (2-MAG) is produced when lipase cleaves _______.

A. TAGs
B. cholesterol
C. phospholipids

Answer 7

A. TAGs

Question 8

_____ removes FA from phospholipids.

A. pancreatic lipase
B. phospholipase A2
C. esterase

Answer 8

B. phospholipase A2

Question 9

The pancreas secretes _____, which cleaves fatty acids from cholesterols.

A. pancreatic lipase
B. phospholipase A2
C. esterase

Answer 9

C. esterase

Question 10

Following cleavage from glycerol, FAs are absorbed into the ________.

A. Portal hepatic bloodstream
B. Liver
C. Intestinal epithelium

Answer 10

C. Intestinal epithelium

Question 11

Once in intestinal epithelium, short/medium FAs are packaged into _____.

A. LDLs
B. HDLs
C. cholymicrons
D. micelles

Answer 11

D. micelles

Question 12

Dietary lipids within micelles also contain:

Answer 12

cholesterol, fat soluble vitamins, and phospholipids

Question 13

Within intenstinal epithelium, FAs and 2-MAG is condensend in the ____ to form _____.

Answer 13

smooth ER;

TAGs (resynthesized)

*TAGs broken down for transport, then reformed

Question 14

After TAG is resynthesized in the intestinal epithelium, it is packaged into ______, which contain proteins, phospholipids, cholesterol, and other fat soluble vitamins.

A. chylomicrons
B. apoproteins
C. miscelles

Answer 14

A. chylomicrons

Question 15

A ____ is a blood transport molecule forlipids

Answer 15

chylomicron

Question 16

Chylomicrons are secreted into the lymphatic system via what process?

Answer 16

exocytosis

Question 17

Liver cell receptors recognize this protein on chylomicrons, and allows for endocytosis

A. ApoE
B. ApoCII
C. LDL

Answer 17

A. ApoE

Question 18

Triglycerides are digested by different enzymes dependent upon the _____ of fatty acids.

a. saturation
b. length
d. backbone released from

Answer 18

b. length

Question 19

Lipoprotein lipase is located on _____ cells of muscle/adipose tissue.

Answer 19

capillary endothelial

Question 20

Lipoprotein lipase is activated by _____.

A. ApoCII
B. ApoE
C. Chylomicrons

Answer 20

A. ApoCII

Question 21

What are the three “steps” of utilization of FAs

Answer 21

1) Mobilization - TAGs broken down to FA/glycerol
2) activation - activation and transport to mitochondria
3) Degradation - breakdown of FA to Acetyl CoA

Question 22

_____ breaks down TAGs to DAGs

Answer 22

ATGL (adipose triglyceride lipase)

Question 23

____ breaks down DAGs to MAGs

Answer 23

Hormonally Sensitive lipase

Question 24

MAG is broken down to glycerol and FA by ______

Answer 24

MAG lipase

Question 25

Break down of TAGs occurs through a GPCR mechanism, which is activated by _______.

Answer 25

Glucagon and epinephrine (in low energy states)

Question 26

Activation of glycerol occurs in the ____ and is catalyzed by ______.

Answer 26

liver; glycerol kinase (ONLY present in the liver)

Question 27

Activation of FAs occurs in what portion of the cell?

Answer 27

cytosol

Question 28

Activation of fatty acids occurs when FAs bind to _____.

Answer 28

Sulfhydryl group of CoA

Question 29

Fatty acids are transferred into the mitochondria via Acyl-Carnitine Translocase. How is fatty acid transferred?

Answer 29

Acyl-CoA is broken down to form acyl-carnitine, which is moved into the mitochondria.

Question 30

Steps of beta-oxidation

Answer 30

Acyl-CoA oxidation (producing FADH2)
Hydration
Oxidation (forming NADH)
Thiolysis (forming Acyl-CoA and Acetyl-CoA)

Question 31

Mono-unsaturated FAs require what additional enzymes?

Answer 31

Isomerase (cis-double bonds not usable)

Question 32

Poly-unsaturated FAs require what enzymes for break down?

Answer 32

Isomerase (to form a trans double bond)

Reductase (to reduce the second double bond)

Question 33

The TCA cycle has a large effect on the oxidation of FAs. Acetyl-CoA formed by FA oxidation will enter the TCA cycle. However, if a patient has a low carbohydrate diet, they will not oxidize carbs. Why?

Answer 33

Low carb diets prevent the production of oxaloacetate, which in turn does not combine with Acetyl-CoA to run the TCA cycle.

Question 34

Ketone bodies are formed in the ____ during states of fasting or diabetes.

A. Kidney
B. Intestines
C. Liver
D. Muscle

Answer 34

C. Liver

Question 35

In fasting/diabetic states, glucose is either not present or unable to be used, respectively. In that case, what occurs instead?

Answer 35

TAGs are broken down to glycerol/FAs. These are then used to form ketone bodies, which enter the TCA cycle for ATP production.

Question 36

What three ketone bodies are formed in diabetic patients.

Answer 36

Acetoacetate

D-3-hydroxybutyrate

Acetone

Question 37

D-3-Hydroxybutyrate can be changed into ____ when reacted with NAD+. What will eventually be formed by this reaction?

Answer 37

Acetoacetate; 2x acetyl-CoA