Lecture 16 - Fatty Acid Synthesis and Storage Flashcards
Fatty acid synthesis is favored by what two molecule types (in excess)?
- Excess glucose
2. Excess amino acids
_____ activates FA synthesis by activating protein phosphatase. This dephosphorylates Acetyl-CoA carboxylase, which activates to convert acetyl-CoA –> malonyl CoA.
Insulin
Insulin also stimulates synthesis and storage of _________ by promoting uptake of FA and glucose in adipose tissue.
triglycerides
The inner mitochondrial membrane is impermeable to acetyl-CoA, so it is translocated as _________.
citrate
What enzyme catalyzes the rate-limiting step in FA synthesis?
Acetyl-CoA carboxylase catalyzes the rate limiting step, converting Acetyl-CoA to malonyl-CoA.
Which is an allosteric inhibitor of acetyl-CoA carboxylase?
A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin
A
Which is an allosteric activator of acetyl-CoA carboxylase?
A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin
B
Which activates Protein Kinase A (PKA) via cAMP, which in turn phosphorylates and DEACTIVATES acetyl-CoA carboxylase?
A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin
C
Which activates protein phosphatase, which dephosphorylates and ACTIVATES acetyl-CoA carboxylase?
A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin
D
The 7 malonyl-CoA requires for FA synthesis are generated from carboxylation of ____________.
acetyl-CoA (by enzyme ACC)
The reaction:
acetyl-CoA + OAA –> citrate + CoASH
is catalyzed by _________.
A. Malic DH
B. Malic enzyme
C. Citrate lyase
D. Citrate synthase
D
The reaction:
citrate + ATP + CoASH –>
acetyl-CoA + OAA + ADP + Pi
is catalyzed by ________.
A. Malic DH
B. Malic enzyme
C. Citrate lyase
D. Citrate synthase
C
Both steps of the pentose phosphate pathway generate _________ to power FA synthesis.
NADPH
Which catalyzes the condensation step in FA synthesis?
A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase
A
Which catalyzes the dehydration step in FA synthesis?
A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase
C
Which catalyzes reduction of the double bond to give a fully saturated FA that is 2 carbons longer?
A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase
D
The cofactor for the acyl carrier protein (ACP) in FA synthesis is ____________.
phosphopantetheine
What is the function of acyl carrier protein in FA synthesis?
It acts as an anchor for the growing FA chain.
The end product of FA synthesis in the liver is _________.
palmitic acid (16:0)
The end product of FA synthesis in the lactating mammary gland is ________.
decanoic acid (10:0)
What characteristic of the end product of FA synthesis in the lactating mammary gland makes it able to freely diffuse across the intestinal epithelial cells into the portal blood?
it is a C10 - medium chain fatty acid
Fatty acids from the liver are delivered to adipose tissue via what two molecules?
- VLDL
2. Chylomicrons
VLDL particles contain what apoprotein that activates the lipoprotein lipase?
A. Apo-B48
B. Apo-B100
C. Apo-CII
D. None of these
C
Fatty acid conversion to triglycerides in adipose tissue is activated by the conversion to _________.
fatty acyl-CoA
Insulin stimulates both the production of LpL and the entry of glucose into the adipocyte via what glucose transporter?
A. GLUT1
B. GLUT2
C. GLUT3
D. GLUT4
D
What are 3 functions of phospholipids?
- Structural component of membranes
- Enzyme activation
- Second messenger signaling
Note: phospholipids are also important in lung and detergent functioning
________ hydrolyzes TAG in the mobilization of fatty acids from triglycerides.
A. ATGL
B. HSL
C. MAG
D. All of these
A (triacyltriglycerol lipase)
________ hydrolyzes mainly DAG but also TAG in the mobilization of fatty acids from triglycerides.
A. ATGL
B. HSL
C. MAG
D. All of these
B
________ hydrolyzes MGL in the mobilization of fatty acids from triglycerides.
A. ATGL
B. HSL
C. MAG
D. All of these
C
Activity in ______ during the mobilization of fatty acids from triglycerides is stimulated by glucagon, epinephrine, and ACTH via phosphorylation and activation.
A. ATGL
B. HSL
C. MAG
D. All of these
D (however, mostly HSL is stimulated!)
