Question 1

Which one of the following statements best applies to synthesis of fatty acids in E.coli extracts?

Accepted Answer

A) Acyl intermediates are thioesters of a low molecular weight protein called acyl carrier protein. 
B) CO2 or HCO3- is essential. 
C) Reducing equivalents are provided by NADPH. 
D) The ultimate source of all the carbon atoms in the fatty acid product is acetyl-CoA. 
E) All of the above 
A) Acyl intermediates are thioesters of a low molecular weight protein called acyl carrier protein. 
B) CO2 or HCO3- is essential. 
C) Reducing equivalents are provided by NADPH. 
D) The ultimate source of all the carbon atoms in the fatty acid product is acetyl-CoA. 
E) All of the above

Question 2

Describe the mechanism for moving acetyl-CoA produced in the mitochondrial matrix into the cytosol for fatty acid synthesis.

Accepted Answer

Acetyl-CoA in the mitochondrial matrix c

Question 3

Which of the following is not true about precursors required for fatty acid synthesis in animal cells?

Accepted Answer

A) NADPH is produced in the cytosol by the pentose phosphate pathway. 
B) NADPH is produced in the nucleus by malic enzyme. 
C) Acetyl-CoA is transported out of the mitochondrion via the citrate shuttle. 
D) CoA is not transported across the mitochondrial membrane. 
E) Malonyl-CoA is formed in the cytosol. 
A) NADPH is produced in the cytosol by the pentose phosphate pathway. 
B) NADPH is produced in the nucleus by malic enzyme. 
C) Acetyl-CoA is transported out of the mitochondrion via the citrate shuttle. 
D) CoA is not transported across the mitochondrial membrane. 
E) Malonyl-CoA is formed in the cytosol.

Question 4

Describe the formation of farnesyl pyrophosphate from activated isoprenyl units.

Accepted Answer

This is the reaction in which

Question 5

Describe (briefly)two classes of genetic defects in humans that could produce an elevated blood serum cholesterol level.

Accepted Answer

(1)Mutations in the LDL receptor result

Question 6

Chylomicrons carry in the .

Accepted Answer

A) triacylglycerols;cell 
B) triacylglycerols;blood 
C) cholesterols;blood 
D) fatty acids;blood 
E) fatty acids;cell 
A) triacylglycerols;cell 
B) triacylglycerols;blood 
C) cholesterols;blood 
D) fatty acids;blood 
E) fatty acids;cell

Question 7

The synthesis of fatty acids and their breakdown by $\beta$-oxidation occur by separate pathways.Compare the two paths by filling in the blanks below.(Some blanks may require more than one answer. )

Accepted Answer

The answer of The synthesis of fatty acids and their...

Question 8

Show the pathway from acetyl-CoA to mevalonate,indicating the roles of any cofactors.

Accepted Answer

The answer of Show the pathway from acetyl-CoA to mevalonate,indicating...

Question 9

Which of the following contains the highest percentage of cholesteryl esters?

Accepted Answer

A) Chylomicrons 
B) VLDL 
C) LDL 
D) HDL 
E) None of the above contain any cholesteryl esters. 
A) Chylomicrons 
B) VLDL 
C) LDL 
D) HDL 
E) None of the above contain any cholesteryl esters.

Question 10

Cholesterol is synthesized from:

Accepted Answer

A) acetyl-CoA. 
B) choline. 
C) lipoic acid. 
D) malate. 
E) oxalate. 
A) acetyl-CoA. 
B) choline. 
C) lipoic acid. 
D) malate. 
E) oxalate.

Question 11

The synthesis of both glycerophospholipids and triacylglycerols involves:

Accepted Answer

A) CDP-choline. 
B) CDP-diacylglycerol. 
C) phosphatidate phosphatase. 
D) phosphatidic acid. 
E) phosphoethanolamine. 
A) CDP-choline. 
B) CDP-diacylglycerol. 
C) phosphatidate phosphatase. 
D) phosphatidic acid. 
E) phosphoethanolamine.

Question 12

The reaction sequence that leads to fatty acid synthesis includes (1)condensation, (2)first reduction reaction, (3)dehydration,and (4)second reduction.Show the first reduction reaction,with any required cofactors.

Accepted Answer

@#LAT-DLM&-ketoacyl-ACP + NADP

Question 13

Show the structure of each intermediate in the conversion of $\beta$-hydroxybutyryl-ACP to butyryl-ACP by the fatty acid synthetase complex.Show where cofactors participate.In your first intermediate,circle the carbon atoms that are derived from malonyl-CoA.

Accepted Answer

@#LAT-DLM&-hydroxybutyryl-ACP is first dehydrated,

Question 14

Which of the following is true of sphingolipid synthesis?

Accepted Answer

A) All of the carbon atoms of palmitate and serine are incorporated into sphingosine. 
B) CDP-sphingosine is the activated intermediate. 
C) CO2 is produced during the synthesis of ceramide from palmitate and serine. 
D) Glucose 6-phosphate is the direct precursor of the glucose in cerebrosides. 
E) Phosphatidic acid is a key intermediate in the pathway. 
A) All of the carbon atoms of palmitate and serine are incorporated into sphingosine. 
B) CDP-sphingosine is the activated intermediate. 
C) CO2 is produced during the synthesis of ceramide from palmitate and serine. 
D) Glucose 6-phosphate is the direct precursor of the glucose in cerebrosides. 
E) Phosphatidic acid is a key intermediate in the pathway.

Question 15

Show the structure of isopentenyl pyrophosphate and of dimethylallyl pyrophosphate.Connect with a dotted line the two carbon atoms that will be joined when these two molecules condense to form the 10-carbon intermediate in cholesterol biosynthesis.

Accepted Answer

The "tail" of isopentenyl pyro

Question 16

Show the two different biosynthetic pathways from phosphatidic acid to phosphatidylcholine.You may use shorthand notation for phosphatidic acid,but name any cofactors required in the path and show where they are involved.

Accepted Answer

Phosphatidic acid condenses with CTP to

Question 17

Show the pathway from mevalonate to dimethylallyl pyrophosphate,indicating where any cofactors participate.

Accepted Answer

The answer of Show the pathway from mevalonate to dimethylallyl...

Question 18

The rate-limiting step in fatty acid synthesis is:

Accepted Answer

A) condensation of acetyl-CoA and malonyl-CoA. 
B) formation of acetyl-CoA from acetate. 
C) formation of malonyl-CoA from malonate and coenzyme A. 
D) the reaction catalyzed by acetyl-CoA carboxylase. 
E) the reduction of the acetoacetyl group to a  $\beta$-hydroxybutyryl group. 
A) condensation of acetyl-CoA and malonyl-CoA. 
B) formation of acetyl-CoA from acetate. 
C) formation of malonyl-CoA from malonate and coenzyme A. 
D) the reaction catalyzed by acetyl-CoA carboxylase. 
E) the reduction of the acetoacetyl group to a  $\beta$-hydroxybutyryl group.

Exam 21: Lipid Biosynthesis

Which one of the following statements best applies to synthesis of fatty acids in E.coli extracts?

Describe the mechanism for moving acetyl-CoA produced in the mitochondrial matrix into the cytosol for fatty acid synthesis.

Which of the following is not true about precursors required for fatty acid synthesis in animal cells?

Describe the formation of farnesyl pyrophosphate from activated isoprenyl units.

Describe (briefly)two classes of genetic defects in humans that could produce an elevated blood serum cholesterol level.

Chylomicrons carry in the .

The synthesis of fatty acids and their breakdown by β\betaβ -oxidation occur by separate pathways.Compare the two paths by filling in the blanks below.(Some blanks may require more than one answer. )

Show the pathway from acetyl-CoA to mevalonate,indicating the roles of any cofactors.

Which of the following contains the highest percentage of cholesteryl esters?

Cholesterol is synthesized from:

The synthesis of both glycerophospholipids and triacylglycerols involves:

The reaction sequence that leads to fatty acid synthesis includes (1)condensation, (2)first reduction reaction, (3)dehydration,and (4)second reduction.Show the first reduction reaction,with any required cofactors.

Show the structure of each intermediate in the conversion of β\betaβ -hydroxybutyryl-ACP to butyryl-ACP by the fatty acid synthetase complex.Show where cofactors participate.In your first intermediate,circle the carbon atoms that are derived from malonyl-CoA.

Which of the following is true of sphingolipid synthesis?

Show the structure of isopentenyl pyrophosphate and of dimethylallyl pyrophosphate.Connect with a dotted line the two carbon atoms that will be joined when these two molecules condense to form the 10-carbon intermediate in cholesterol biosynthesis.

Show the two different biosynthetic pathways from phosphatidic acid to phosphatidylcholine.You may use shorthand notation for phosphatidic acid,but name any cofactors required in the path and show where they are involved.

Show the pathway from mevalonate to dimethylallyl pyrophosphate,indicating where any cofactors participate.

The rate-limiting step in fatty acid synthesis is:

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Show the structure of each intermediate in the conversion of $\beta$ -hydroxybutyryl-ACP to butyryl-ACP by the fatty acid synthetase complex.Show where cofactors participate.In your first intermediate,circle the carbon atoms that are derived from malonyl-CoA.