Lecture 32 - Lipid Metabolism I Flashcards
Lingual and gastric lipases digest _____fatty acids.
a. long chain (> 12 C)
b. short chain (
b. short chain
Emulsification of fats occurs by suspension within ______.
a. cholymicrons
b. bile salts
b. bile salts
Which of the following is responsible for contraction of the gallbladder?
a. bile releasing enzyme
b. renin
c. secretin
d. cholecystokinin
d. cholecystokinin
(chole-gallbladder; cysto-bladder (the gallbladder is a pouch; kinin-think “kinetic”, it moves the gallbladder to secrete bile)
T/F: After emulsification, the bile salt/FA mixture becomes the substrate of pancreatic lipases?
True
What hormone stimulates the release of bicarbonate to neutralize the acidic pH of bile salts?
secretin
True/False: pancreatic lipase is specific for short chain fatty acids.
False. Pancreatic lipase digests all lengths of FAs
2-Monoacylglycerol (2-MAG) is produced when lipase cleaves _______.
A. TAGs
B. cholesterol
C. phospholipids
A. TAGs
_____ removes FA from phospholipids.
A. pancreatic lipase
B. phospholipase A2
C. esterase
B. phospholipase A2
The pancreas secretes _____, which cleaves fatty acids from cholesterols.
A. pancreatic lipase
B. phospholipase A2
C. esterase
C. esterase
Following cleavage from glycerol, FAs are absorbed into the ________.
A. Portal hepatic bloodstream
B. Liver
C. Intestinal epithelium
C. Intestinal epithelium
Once in intestinal epithelium, short/medium FAs are packaged into _____.
A. LDLs
B. HDLs
C. cholymicrons
D. micelles
D. micelles
Dietary lipids within micelles also contain:
cholesterol, fat soluble vitamins, and phospholipids
Within intenstinal epithelium, FAs and 2-MAG is condensend in the ____ to form _____.
smooth ER;
TAGs (resynthesized)
*TAGs broken down for transport, then reformed
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. chylomicrons
A ____ is a blood transport molecule forlipids
chylomicron
Chylomicrons are secreted into the lymphatic system via what process?
exocytosis
Liver cell receptors recognize this protein on chylomicrons, and allows for endocytosis
A. ApoE
B. ApoCII
C. LDL
A. ApoE
Triglycerides are digested by different enzymes dependent upon the _____ of fatty acids.
a. saturation
b. length
d. backbone released from
b. length
Lipoprotein lipase is located on _____ cells of muscle/adipose tissue.
capillary endothelial
Lipoprotein lipase is activated by _____.
A. ApoCII
B. ApoE
C. Chylomicrons
A. ApoCII
What are the three “steps” of utilization of FAs
1) Mobilization - TAGs broken down to FA/glycerol
2) activation - activation and transport to mitochondria
3) Degradation - breakdown of FA to Acetyl CoA
_____ breaks down TAGs to DAGs
ATGL (adipose triglyceride lipase)
____ breaks down DAGs to MAGs
Hormonally Sensitive lipase
MAG is broken down to glycerol and FA by ______
MAG lipase
Break down of TAGs occurs through a GPCR mechanism, which is activated by _______.
Glucagon and epinephrine (in low energy states)
Activation of glycerol occurs in the ____ and is catalyzed by ______.
liver; glycerol kinase (ONLY present in the liver)
Activation of FAs occurs in what portion of the cell?
cytosol
Activation of fatty acids occurs when FAs bind to _____.
Sulfhydryl group of CoA
Fatty acids are transferred into the mitochondria via Acyl-Carnitine Translocase. How is fatty acid transferred?
Acyl-CoA is broken down to form acyl-carnitine, which is moved into the mitochondria.
Steps of beta-oxidation
Acyl-CoA oxidation (producing FADH2)
Hydration
Oxidation (forming NADH)
Thiolysis (forming Acyl-CoA and Acetyl-CoA)
Mono-unsaturated FAs require what additional enzymes?
Isomerase (cis-double bonds not usable)
Poly-unsaturated FAs require what enzymes for break down?
Isomerase (to form a trans double bond)
Reductase (to reduce the second double bond)
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?
Low carb diets prevent the production of oxaloacetate, which in turn does not combine with Acetyl-CoA to run the TCA cycle.
Ketone bodies are formed in the ____ during states of fasting or diabetes.
A. Kidney
B. Intestines
C. Liver
D. Muscle
C. Liver
In fasting/diabetic states, glucose is either not present or unable to be used, respectively. In that case, what occurs instead?
TAGs are broken down to glycerol/FAs. These are then used to form ketone bodies, which enter the TCA cycle for ATP production.
What three ketone bodies are formed in diabetic patients.
Acetoacetate
D-3-hydroxybutyrate
Acetone
D-3-Hydroxybutyrate can be changed into ____ when reacted with NAD+. What will eventually be formed by this reaction?
Acetoacetate; 2x acetyl-CoA
