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Exam 3 Biochem-Lecture 29
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41
Chemistry
Professional
11/05/2009
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Term
Example of Phospholipid is
 Definition
Dipalmitoylphosphatidylcholine (DPCC)  or dipalmitoyllecithin
Term
Dipalmitoylphosphatidylcholine (DPCC) or dipalmitoyllecithin
 Definition
  • is the major component of surfactant in the lungs (80%).
  • It is produced by type II epithelial cells and prevents atelectasis
  • Decreases surface tension of the fluid layer of the lung.
  • Surfactant also contains: PG, PI and 2 surfactant proteins.
Term

 

Phosphatidylethanolamine Synthesis occur in

Definition
  • liver
  • brain
Term

 

Phosphatidylethanolamine-N-methyltransferase

Definition
occurs in liver only
Term

 

Phospholipase A1
Definition
  •  inhibited by  glucocorticoid
  • can remove fatty acids selectively from carbon 1 of the glycerol backbone.
Term

 

•Phospholipase  A2can
Definition

remove fatty acids selectively from carbon 2 of the glycerol backbone.
Term

 

Roles of Cholesterol:

 Definition
  • Membrane structure
  • A precursor for the synthesis of the steroid hormones and bile acids.
Term
Both dietary cholesterol and that synthesized de novo are transported through the circulation in ....?
 Definition
lipoprotein particles
Term
The form in which cholesterol is stored in cells
 Definition
cholesteryl esters,
Term

 

•The synthesis and utilization of cholesterol must be tightly regulated in order to prevent:
Definition
  • over-accumulation
  • abnormal deposition within the body.
Term
The abnormal deposition of cholesterol and cholesterol-rich lipoproteins in the coronary arteries cause:
Definition
Atherosclerosis
Term
Most plasma cholesterol is in a/an
 Definition
 esterified form
Term

Most plasma cholesterol is in an esterified form, with a fatty acid attached at....?

This makes it even more hydrophobic then free cholesterol.

 Definition
 C-3
Term

 

All carbon atoms of cholesterol are derived from ?
 Definition
acetate
Term

 

In Cholesterol Biosynthesis, reducing power in the form of NADPH is provided mainly by glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of the ..........pathway????
 Definition
pentose phosphate pathway
Term
In Cholesterol Biosynthesis, reducing power in the form of ............ is provided mainly by glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of the pentose phosphate pathway????
 Definition
NADPH
Term
Cholesterol Biosynthesis has ....major steps
 Definition
5
Term

 

 

•All the reduction reactions of cholesterol biosynthesis use ........as a cofactor.
Definition
NADPH
Term

In Cholesterol Biosynthesis, Acetyl-CoA units are converted to mevalonate by a series of reactions that begins with the formation of .....?

 Definition
HMG-CoA.
Term
In Cholesterol Biosynthesis, HMG-CoA is converted to mevalonate by ....?
 Definition
HMG-CoA reductase
Term
What is the rate limiting step of cholesterol biosynthesis???
 Definition
The reaction catalyzed by HMG-CoA reductase
Term
HMG-CoA reductase is most active in
Definition
in the dephosphorylated state
Term

 

•What activates HMG-CoA reductase activity??
 Definition
Insulin
Term

 

•Statins
 Definition
competitive inhibitors of HMG-CoA Reductase.
Term

 

Drug Therapy for Dyslipidemia

Definition

 

–Simvastatin
–Pravastatin
–Lovastatin
Term
Statins exert their major effect by
 Definition
reduce LDL levels
Term
Statins affect blood cholesterol levels by
Definition
  1. inhibiting cholesterogenesis in the liver
  2.  which results in increased expression of the LDL receptor gene
  3. The greater number of LDL receptors on the surface of hepatocytes results in increased removal of LDL from the blood thereby lowering LDL-C levels
Term
The greater number of LDL receptors on the surface of hepatocytes results in
Definition
  1. increased removal of LDL from the blood
  2. thereby lowering LDL-C levels
Term

 

The most abundant bile acids in human bile are
 Definition
  • chenodeoxycholic acid (45%)
  • cholic acid (31%).
Term
chenodeoxycholic acid (45%) and cholic acid (31%) are
 Definition
primary bile acids
Term

 

•Within the intestines the primary bile acids are acted upon by bacteria and converted to
Definition
the secondary bile acids
Term
Primary bile acid is converted to secondary bile acid
 Definition
  • deoxycholate (from cholate
  • lithocholate (from chenodeoxycholate).
Term
 
•In liver the carboxyl group of primary and secondary bile acids is conjugated via ..........bond to either glycine or taurine before their being resecreted into the bile canaliculi.
Definition
an amide bond
Term
Bile acids perform 4 physiologically significant functions:
Definition

1. Eliminate of excess cholesterol.

2. Solubilize cholesterol in the bile, thereby preventing the precipitation of cholesterol in the gallbladder.

3. Facilitate the digestion of dietary triacylglycerols

4. Facilitate the intestinal absorption of fat-soluble vitamins.

Term
Dietary cholesterol is transported from the small intestine to the liver within....?
 Definition
chylomicrons
Term
Cholesterol synthesized by the liver, and excess dietary cholesterol in the liver are  transported in the serum within ....?
 Definition
LDLs
Term
cholesterol is excreted in the bile as.........  or as .............following conversion to bile acids in the liver.
 Definition
  • free cholesterol
  • bile salts

 
Term

 

•Reverse cholesterol transport allows peripheral cholesterol to be returned to the liver in .....?
 Definition
HDLs
Term
Cholesterol found in plasma membranes can be extracted by ........ and esterified by the ..............
 Definition
  • HDLs
  • HDL-associated enzyme LCAT
Term

 

•The liver synthesizes .......... and these are converted to ........... through the action of endothelial cell-associated lipoprotein lipase.
Definition
  • VLDLs
  • LDLs
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