Lecture 32 - Lipid Metabolism I Flashcards Preview

Biochemistry > Lecture 32 - Lipid Metabolism I > Flashcards

Flashcards in Lecture 32 - Lipid Metabolism I Deck (37)
Loading flashcards...
1
Q

Lingual and gastric lipases digest _____fatty acids.

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

A

b. short chain

2
Q

Emulsification of fats occurs by suspension within ______.

a. cholymicrons
b. bile salts

A

b. bile salts

3
Q

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

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

A

d. cholecystokinin

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

4
Q

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

A

True

5
Q

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

A

secretin

6
Q

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

A

False. Pancreatic lipase digests all lengths of FAs

7
Q

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

A. TAGs
B. cholesterol
C. phospholipids

A

A. TAGs

8
Q

_____ removes FA from phospholipids.

A. pancreatic lipase
B. phospholipase A2
C. esterase

A

B. phospholipase A2

9
Q

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

A. pancreatic lipase
B. phospholipase A2
C. esterase

A

C. esterase

10
Q

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

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

A

C. Intestinal epithelium

11
Q

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

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

A

D. micelles

12
Q

Dietary lipids within micelles also contain:

A

cholesterol, fat soluble vitamins, and phospholipids

13
Q

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

A

smooth ER;

TAGs (resynthesized)

*TAGs broken down for transport, then reformed

14
Q

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

A

A. chylomicrons

15
Q

A ____ is a blood transport molecule forlipids

A

chylomicron

16
Q

Chylomicrons are secreted into the lymphatic system via what process?

A

exocytosis

17
Q

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

A. ApoE
B. ApoCII
C. LDL

A

A. ApoE

18
Q

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

a. saturation
b. length
d. backbone released from

A

b. length

19
Q

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

A

capillary endothelial

20
Q

Lipoprotein lipase is activated by _____.

A. ApoCII
B. ApoE
C. Chylomicrons

A

A. ApoCII

21
Q

What are the three “steps” of utilization of FAs

A

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

22
Q

_____ breaks down TAGs to DAGs

A

ATGL (adipose triglyceride lipase)

23
Q

____ breaks down DAGs to MAGs

A

Hormonally Sensitive lipase

24
Q

MAG is broken down to glycerol and FA by ______

A

MAG lipase

25
Q

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

A

Glucagon and epinephrine (in low energy states)

26
Q

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

A

liver; glycerol kinase (ONLY present in the liver)

27
Q

Activation of FAs occurs in what portion of the cell?

A

cytosol

28
Q

Activation of fatty acids occurs when FAs bind to _____.

A

Sulfhydryl group of CoA

29
Q

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

A

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

30
Q

Steps of beta-oxidation

A

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

31
Q

Mono-unsaturated FAs require what additional enzymes?

A

Isomerase (cis-double bonds not usable)

32
Q

Poly-unsaturated FAs require what enzymes for break down?

A

Isomerase (to form a trans double bond)

Reductase (to reduce the second double bond)

33
Q

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?

A

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

34
Q

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

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

A

C. Liver

35
Q

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

A

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

36
Q

What three ketone bodies are formed in diabetic patients.

A

Acetoacetate

D-3-hydroxybutyrate

Acetone

37
Q

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

A

Acetoacetate; 2x acetyl-CoA