Question 1

Which of the following is the key regulated enzyme in urea synthesis?

Accepted Answer

A)  carbamoyl phosphate synthetase I 
B)  glutamate dehydrogenase 
C)  arginase 
D)  argininosuccinase 
A)  carbamoyl phosphate synthetase I 
B)  glutamate dehydrogenase 
C)  arginase 
D)  argininosuccinase A

Question 2

How does Viagra interact with the mechanism of endothelial nitric oxide synthase?

Accepted Answer

As illustrated in Figure 17.64 in the text, sildenafil (Viagra) maintains the vasodilated state in erectile tissue by inhibiting the activity of cGMP phosphodiesterase, which has the net result of increasing intracellular cGMP levels by delaying its degradation.

Question 3

Summarize the mechanism for control of endothelial nitric oxide.

Accepted Answer

Calcium-calmodulin binds to the endothelial nitric oxide synthase enzyme in response to receptor-mediated signaling through G protein-coupled receptors. See Figure 17.64 in the text.

Question 4

Using the figure below, illustrate the two final products and identify the amino group on glutamine that gets transferred.

Accepted Answer

The answer of Using the figure below, illustrate the two...

Question 5

Summarize the synthesis of the catecholamines.

Accepted Answer

Tyrosine is the metabolons precursor to

Question 6

Eukaryotic proteasome selectively degrade which type of proteins?

Accepted Answer

A)  all proteins; they are not selective 
B)  ubiquitinated proteins 
C)  phosphorylated proteins 
D)  ATP-dependent proteins 
A)  all proteins; they are not selective 
B)  ubiquitinated proteins 
C)  phosphorylated proteins 
D)  ATP-dependent proteins

Question 7

A negative nitrogen balance in a person would be an indicator of

Accepted Answer

A)  accumulation of nitrogen in the body. 
B)  a diet heavy in protein. 
C)  starvation. 
D)  overall good health. 
A)  accumulation of nitrogen in the body. 
B)  a diet heavy in protein. 
C)  starvation. 
D)  overall good health.

Question 8

Compare the function of pepsin with that of secretin.

Accepted Answer

A)  Pepsin cleaves trypsin, whereas secretin activates proteolytic zymogens. 
B)  Pepsin activates trypsinogen, whereas secretin neutralizes pH back to 7. 
C)  Pepsin denatures proteins, whereas secretin cleaves polypeptide bonds. 
D)  Pepsin cleaves polypeptide bonds, whereas secretin neutralizes pH back to 7. 
A)  Pepsin cleaves trypsin, whereas secretin activates proteolytic zymogens. 
B)  Pepsin activates trypsinogen, whereas secretin neutralizes pH back to 7. 
C)  Pepsin denatures proteins, whereas secretin cleaves polypeptide bonds. 
D)  Pepsin cleaves polypeptide bonds, whereas secretin neutralizes pH back to 7.

Question 9

The carbon skeletons of all 20 amino acids side chains are derived from just seven metabolic intermediates and their associated pathways. What are those intermediates and pathways?

Accepted Answer

Three glycolytic pathway intermediates:

Question 10

Classify the 20 amino acids as glucogenic, ketogenic, or both.

Accepted Answer

The answer of Classify the 20 amino acids as glucogenic,...

Question 11

During vigorous anaerobic exercise, glycogen degradation leads to the buildup of pyruvate. How does the alanine-glucose cycle prevent a toxic buildup?

Accepted Answer

The alanine-glucose cycle removes excess

Question 12

Why do angina patients carry nitroglycerine with them?

Accepted Answer

A)  as a rapid source of NO for blood vessel dilation 
B)  as a source of ammonia for muscle relaxation 
C)  to inhibit acetylcholine release from neurons 
D)  to inhibit cGMP phosphodiesterase 
A)  as a rapid source of NO for blood vessel dilation 
B)  as a source of ammonia for muscle relaxation 
C)  to inhibit acetylcholine release from neurons 
D)  to inhibit cGMP phosphodiesterase

Question 13

Which of the following is the correct net reaction for the combined reaction of glutamine synthetase and glutamate synthase?

Accepted Answer

A)  "$\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+ $\rightarrow$NAD+ + ADP + Pi + glutamate" 
B)  "NAD+ + ADP + Pi + glutamate $\rightarrow$ $\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+" 
C)  "$\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+ $\rightarrow$NAD+ + ADP + Pi + glutamine" 
D)  "glutamate + NH4+ + ATP + NADH + H+ $\rightarrow$ NAD+ + ADP + Pi + $\alpha$-ketoglutarate" 
A)  "$\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+ $\rightarrow$NAD+ + ADP + Pi + glutamate" 
B)  "NAD+ + ADP + Pi + glutamate $\rightarrow$ $\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+" 
C)  "$\alpha$-ketoglutarate + NH4+ + ATP + NADH + H+ $\rightarrow$NAD+ + ADP + Pi + glutamine" 
D)  "glutamate + NH4+ + ATP + NADH + H+ $\rightarrow$ NAD+ + ADP + Pi + $\alpha$-ketoglutarate"

Question 14

How can individuals with urea cycle deficiencies be treated with sodium phenylbutyrate?

Accepted Answer

One way to remove excess nitrogen in ind

Question 15

What are the six steps of the nitrogenase reaction?

Accepted Answer

(1) Exchange of 2 ADP for 2 ATP with red

Question 16

What is the net reaction of nitrogen assimilation in plants?

Accepted Answer

A)  "Glutamate + ADP + Pi + NADP+ $\rightarrow$$\alpha$-Ketoglutarate + NH4+ + ATP + NADPH + H+" 
B)  "$\alpha$-Ketoglutarate + NH4+ + ATP + NADPH + H+ $\rightarrow$Glutamate + ADP + Pi + NADP+ 
C)  "$\alpha$-Ketoglutarate + NH4+ + ADP + NADPH + H+ $\rightarrow$Glutamate + ATP + Pi + NADP+" 
D)  "$\alpha$-Ketoglutarate + NH4+ + ATP + NADP+ + H+ $\rightarrow$ Glutamate + ADP + Pi + NADPH" 
A)  "Glutamate + ADP + Pi + NADP+ $\rightarrow$$\alpha$-Ketoglutarate + NH4+ + ATP + NADPH + H+" 
B)  "$\alpha$-Ketoglutarate + NH4+ + ATP + NADPH + H+ $\rightarrow$Glutamate + ADP + Pi + NADP+ 
C)  "$\alpha$-Ketoglutarate + NH4+ + ADP + NADPH + H+ $\rightarrow$Glutamate + ATP + Pi + NADP+" 
D)  "$\alpha$-Ketoglutarate + NH4+ + ATP + NADP+ + H+ $\rightarrow$ Glutamate + ADP + Pi + NADPH"

Question 17

Given that glutamate dehydrogenase has a Km of 1 mM and $\Delta$G of +30 kJ/mol, glutamate dehydrogenase only operates best when

Accepted Answer

A)  there is a high concentration of nitrogen available. 
B)  there is a low concentration of nitrogen available. 
C)  operates regardless of nitrogen concentration. 
D)  Not enough information is given. 
A)  there is a high concentration of nitrogen available. 
B)  there is a low concentration of nitrogen available. 
C)  operates regardless of nitrogen concentration. 
D)  Not enough information is given.

Question 18

In the overall reaction of aminotransferase, how many amino acids are produced?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  0 
A)  1 
B)  2 
C)  3 
D)  0

Question 19

The nitrogen balance in the biosphere incorporates which of the following processes?

Accepted Answer

A)  nitrogen fixation, nitrogen assimilation, and nitrate reduction 
B)  nitrogen oxidation and nitrogen reduction 
C)  nitrogen fixation, nitrification, and nitrate reduction 
D)  nitrogen oxidation and nitrate assimilation 
A)  nitrogen fixation, nitrogen assimilation, and nitrate reduction 
B)  nitrogen oxidation and nitrogen reduction 
C)  nitrogen fixation, nitrification, and nitrate reduction 
D)  nitrogen oxidation and nitrate assimilation

Question 20

When amino acids from dietary proteins enter a cell, how are they able to enter the urea cycle?

Accepted Answer

A)  through conversion to glutamine 
B)  through conversion to aspartate 
C)  by degrading down to ammonia 
D)  by getting phosphorylated 
A)  through conversion to glutamine 
B)  through conversion to aspartate 
C)  by degrading down to ammonia 
D)  by getting phosphorylated

Exam 17: Amino Acid Metabolism

Which of the following is the key regulated enzyme in urea synthesis?

How does Viagra interact with the mechanism of endothelial nitric oxide synthase?

Summarize the mechanism for control of endothelial nitric oxide.

Using the figure below, illustrate the two final products and identify the amino group on glutamine that gets transferred.

Summarize the synthesis of the catecholamines.

Eukaryotic proteasome selectively degrade which type of proteins?

A negative nitrogen balance in a person would be an indicator of

Compare the function of pepsin with that of secretin.

The carbon skeletons of all 20 amino acids side chains are derived from just seven metabolic intermediates and their associated pathways. What are those intermediates and pathways?

Classify the 20 amino acids as glucogenic, ketogenic, or both.

During vigorous anaerobic exercise, glycogen degradation leads to the buildup of pyruvate. How does the alanine-glucose cycle prevent a toxic buildup?

Why do angina patients carry nitroglycerine with them?

Which of the following is the correct net reaction for the combined reaction of glutamine synthetase and glutamate synthase?

How can individuals with urea cycle deficiencies be treated with sodium phenylbutyrate?

What are the six steps of the nitrogenase reaction?

What is the net reaction of nitrogen assimilation in plants?

Given that glutamate dehydrogenase has a Km of 1 mM and Δ\DeltaΔ G of +30 kJ/mol, glutamate dehydrogenase only operates best when

In the overall reaction of aminotransferase, how many amino acids are produced?

The nitrogen balance in the biosphere incorporates which of the following processes?

When amino acids from dietary proteins enter a cell, how are they able to enter the urea cycle?

Principles of Biochemistry

Physical Biochemistry: Energy Conversion, Water, and Membranes

Nucleic Acid Structure and Function

Protein Structure

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Cell Signaling Systems

Glycolysis: a Paradigm of Metabolic Regulation

The Citrate Cycle

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Carbohydrate Metabolism

Lipid Structure and Function

Lipid Metabolism

Nucleotide Metabolism

Metabolic Integration

DNA Replication, Repair, and Recombination

RNA Synthesis, Processing, and Gene Silencing

Protein Synthesis, Posttranslational Modification, and Transport

Gene Regulation

Filters

Given that glutamate dehydrogenase has a K_m of 1 mM and $\Delta$ G of +30 kJ/mol, glutamate dehydrogenase only operates best when