Exam 3 Biochem-Lecture 27

Lipids

  •  
  • Hydrophobic
  • Most contain or derived from fatty acids

Function of Lipids

a) major fuel store

b)constitute membranes

c) solubalize nonpolar substance in bodily fluids

d) important signaling molecules

Fatty Acids structure

 

Alkyl chain with a terminal carboxyl group R-COOH

 

Most alkyl chains have an even number of carbon atoms.

Fatty Acids structure include

 

  • Saturated   CH3(CH2)nCOOH
  • Unsaturated  (up to 6 double bonds)

Numerical Formulas of Fatty Acids

 

nShow:
  •  number of carbon atoms
  •   number of double bonds
  • bond location starting with carboxyl carbon.

What is Triacylglycerols?

 

nThree fatty acids esterified to a glycerol backbone

 

nOn a weight basis, pure TAG yields ……….times more ATP than pure glycogen

 

nOn a weight basis, pure TAG yields 2.5 times more ATP than pure glycogen

 

nTAGs can be stored without or with associated water???

 

nTAGs can be stored without associated water, thus decreasing the storage weight.

How many gm of lipid do normal adults eat per day??
Adults ingest 60-150 gm of lipid/day
What are components of lipids that normal adults consume per day?

 

nTriacylglycerols constitute 90% of dietary fat.
nOther 10% are phospholipids, cholesterol, cholesterol esters, and free fatty acids.

Compared to other Lipoprotein classes, HDL:

  • Has highest density
  • Has the most protein
  • Has lowest triacylglycerol
  • Has highest amount of phospholipids

Compared to other Lipoprotein classes, Chylomicron:

  • Has the most triacyglycerol
  • Has the lowest density
  • Has the lowest amount of free cholesterol
  • Has the lowest amount of cholesterol ester
  • Has the lowest amount of phospholipids

 

Compared to other Lipoprotein classes, LDL:

  • Has highest amount of cholesterol ester

 

Liver and Intestine generate HDL to:

 

Deliver cholesterol to the liver for elimination

 

Intestine generate Chylomicron

 

Deliver dietary TAG to peripheral tissues

Liver creates VLD to

 

Deliver de novo TAG to peripheral tissues

 

Fatty acid synthesized from

  • excess carbohydrate
  • amino acids

In FED State:

  • FA assembled into TAGs, packaged into VLDL, secreted into the blood stream
  • VLDL and chylomicrons are hydrolyzed by lipoprotein lipase ApoC-II, activates binding
  • products (FA&glycerol) taken up reassembled to TAG (adipose), or used as fuel (muscle)

Lipid Transport in Fasted State

  • FAs and glycerol released into the blood. FAs transported by serum albumin
  • PROLONGED fasting liver makes ketone bodies, acetoacetate and bhydroxybutyrate

Fatty Acid Biosynthesis occurs in????
cytosol
Palmitic acid (C16H32O2) is first synthesized from

  • carbohydrate intermediates
  • amino acids
  • other fatty acids.

All other fatty acids are made by modification of
palmitic acid
What is formula for palmitic acid???
C16H32O2
Which provides all the carbons for FA synthesis in two carbon units???
Acetyl CoA

 

Acetyl CoA provides all the carbons for FA synthesis in how many carbon units???

 

nAcetyl CoA provides all the carbons for FA synthesis in two carbon units.

Sequence of reactions in Fatty Acid Biosynthesis is carried out by           ????
Sequence of reactions in Fatty Acid Biosynthesis is carried out by fatty acid synthase
Transfer of acetyl CoA from mitochondria to cytosol for fatty acid biosynthesis by what pathway?
Transfer of acetyl CoA from mitochondria to cytosol for fatty acid biosynthesis by citrate cleavage pathway
Transfer of acetyl CoA from where to where for fatty acid biosynthesis by citrate cleavage pathway
Transfer of acetyl CoA from mitochondria to cytosol for fatty acid biosynthesis by citrate cleavage pathway
Transfer of what from mitochondria to cytosol for fatty acid biosynthesis by citrate cleavage pathway
Transfer of acetyl CoA from mitochondria to cytosol for fatty acid biosynthesis by citrate cleavage pathway
In Fatty Acid Biosynthesis, Acetyl-CoA carboxylase requires:

1 molecule of ATP and HCO3

 

In Fatty Acid Biosynthesis, Acetyl-CoA carboxylase is

 

Key control point for fatty acid synthesis

In Fatty Acid Biosynthesis:

  • Biotin is a coenzyme that transfers the CO2 to Acetyl-CoA  to yield malonyl-CoA
  • Citrate is an allosteric activator
  • Palmitoyl CoA is an allosteric inhibitor

 

Which activates Acetyl-CoA Carboxylase  in Fatty Acid Biosynthesis?

 

Dephosphorylation activates Acetyl-CoA Carboxylase

Mammalian FA synthase is

 

is a multienyme polypeptide composed of 2 identical subunits

 

nPalmitoyl-ACP acted on by ………….to produce palmitic acid

 

nPalmitoyl-ACP acted on by thioesterase to produce palmitic acid

Characteristics of Fatty Acyl Synthase

  • It is essential, but not rate limiting
  • Not subject to short term control
  • All activities on a single contiguous protein
  • In animals, the synthase is active only as a dimer

 

The stoichiometry for conversion of acetyl-CoA to palmitate requires …..ATP

The stoichiometry for conversion of acetyl-CoA to palmitate requires 7 ATP

 

nTypes of Modifications of other Fatty Acid

qElongation of Fatty Acids

qDesaturation of Fatty Acids

qHydroxylation of Fatty Acids

 

Elongation of Fatty Acids occurs in

 

Occurs in the endoplasmic reticulum or mitochondria

 

qDesaturation of Fatty Acids occurs in

 

nOccurs in endoplasmic reticulum

 

qHydroxylation of Fatty Acids occurs in

 

nOccurs in mitochondria of many tissues
nOccurs in tissues of the nervous system where long chain fatty acids are needed (C22 and C24)

Tagged In :

Get help with your homework


image
Haven't found the Essay You Want? Get your custom essay sample For Only $13.90/page

Sarah from studyhippoHi there, would you like to get such a paper? How about receiving a customized one?

Check it out