Question 1

In the urea cycle,the second nitrogen of urea enters the cycle in the form of which of the following metabolites?

Accepted Answer

A)   alanine
B)   glutamine
C)   ornithine
D)   aspartate
E)   arginine

Question 2

What protein is used as a tag to identify proteins that are targeted for destruction?

Accepted Answer

A)   proteasome
B)   ubiquitin
C)   destructin
D)   degradin
E)   None of the answers is correct.

Question 3

Ubiquitin-tagged proteins are digested by the __________________.

Accepted Answer

The answer of Ubiquitin-tagged proteins are digested by the __________________....

Question 4

What is the structure of compound X in the following metabolic reaction? Name the type of reaction.

Accepted Answer

<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> This is a...

Question 5

Serine dehydratase catalyzes the conversion of serine into NH4+ and __________________.

Accepted Answer

Question 6

What class of enzymes cleaves most aromatic rings in biological systems?

Accepted Answer

A)   dioxygenases
B)   monooxygenases
C)   biopterin-linked lyases
D)   aromatic oxidases
E)   None of the answers is correct.

Question 7

What molecule is formed from excess ammonium ions by ureotelic organisms?

Accepted Answer

A)   uric acid
B)   urea
C)   ammonia
D)   xanthine
E)   hypoxanthine

Question 8

What product of the first step of methionine degradation is an important methyl group donor?

Accepted Answer

A)   5-methyltetrahydrofolate
B)   methylcobalamin
C)   S-adenosylmethionine
D)   S-adenosylhomocysteine
E)   None of the answers is correct.

Question 9

The C-terminal glycine of ubiquitin is covalently linked to ________________ residues of the protein destined to be degraded.

Accepted Answer

The answer of The C-terminal glycine of ubiquitin is covalently...

Question 10

Nitrogen is transported from muscle to liver in the form of ______________.

Accepted Answer

alanine or...

Question 11

Biopterin is a complicated coenzyme required for the conversion of Phe to Tyr.Why is biopterin not considered a vitamin?

Accepted Answer

It is synthesized in...

Question 12

Surplus amino acids are

Accepted Answer

A)   stored in proteosomes.
B)   stored in protein scaffolds.
C)   used as metabolic fuel.
D)   stored as albumin.
E)   None of the answers is correct.

Question 13

Which amino acids supply carbons as succinyl CoA for eventual entry into metabolism?

Accepted Answer

A)   Met, Val, Leu
B)   Met, Ile, Val
C)   Ile, Val, Leu
D)   Ile, Leu, Gly
E)   None of the answers is correct.

Question 14

What term describes a specific sequence of amino acids that indicates the particular protein should be degraded?

Accepted Answer

A)   consensus sequence
B)   proteasome recognition sequence
C)   degron
D)   ubiquitin binding domain
E)   None of the answers is correct.

Question 15

The hydrolysis of arginine by arginase produces ornithine and ______________.

Accepted Answer

The answer of The hydrolysis of arginine by arginase produces...

Question 16

Which of the following is a product of the transamination of aspartate and α\alphaα -ketoglutarate?

Accepted Answer

A)   glutamine
B)   asparagine
C)   pyruvate
D)   oxaloacetate
E)   None of the answers is correct.

Question 17

In the degradation of amino acids other than Thr or Ser,the amino nitrogens can eventually become the amino group of ___________________.

Accepted Answer

The answer of In the degradation of amino acids other...

Question 18

Describe the structure and function of the 26S proteasome.

Accepted Answer

This 26S proteasome is composed of a 20S...

Question 19

Which amino acid is solely ketogenic?

Accepted Answer

A)   leucine
B)   tryptophan
C)   valine
D)   arginine
E)   isoleucine

Question 20

Uricotelic organisms release nitrogen as

Accepted Answer

A)   NH4+.
B)   arginine.
C)   uric acid.
D)   urea.
E)   None of the answers is correct.

Exam 23: Protein Turnover and Amino Acid Catabolism

In the urea cycle,the second nitrogen of urea enters the cycle in the form of which of the following metabolites?

Correct AnswerverifiedShow Answer

Ubiquitin-tagged proteins are digested by the __________________.

Correct AnswerverifiedShow Answer

Which of the following is a product of the transamination of aspartate and α\alphaα -ketoglutarate?

Correct AnswerverifiedShow Answer

Which amino acids supply carbons as succinyl CoA for eventual entry into metabolism?

Correct AnswerverifiedShow Answer

What is the structure of compound X in the following metabolic reaction? Name the type of reaction.

Correct Answerverified This is a...View AnswerShow Answer

Describe the structure and function of the 26S proteasome.

Correct AnswerverifiedThis 26S proteasome is composed of a 20S...View AnswerShow Answer

What term describes a specific sequence of amino acids that indicates the particular protein should be degraded?

Correct AnswerverifiedShow Answer

In the degradation of amino acids other than Thr or Ser,the amino nitrogens can eventually become the amino group of ___________________.

Correct AnswerverifiedShow Answer

Uricotelic organisms release nitrogen as

Correct AnswerverifiedShow Answer

Which amino acid is solely ketogenic?

Correct AnswerverifiedShow Answer

What protein is used as a tag to identify proteins that are targeted for destruction?

Correct AnswerverifiedShow Answer

Nitrogen is transported from muscle to liver in the form of ______________.

Correct Answerverifiedalanine or...View AnswerShow Answer

The C-terminal glycine of ubiquitin is covalently linked to ________________ residues of the protein destined to be degraded.

Correct AnswerverifiedShow Answer

What class of enzymes cleaves most aromatic rings in biological systems?

Correct AnswerverifiedShow Answer

Biopterin is a complicated coenzyme required for the conversion of Phe to Tyr.Why is biopterin not considered a vitamin?

Correct AnswerverifiedIt is synthesized in...View AnswerShow Answer

What molecule is formed from excess ammonium ions by ureotelic organisms?

Correct AnswerverifiedShow Answer

Serine dehydratase catalyzes the conversion of serine into NH4+ and __________________.

Correct AnswerverifiedShow Answer

The hydrolysis of arginine by arginase produces ornithine and ______________.

Correct AnswerverifiedShow Answer

Surplus amino acids are

Correct AnswerverifiedShow Answer

What product of the first step of methionine degradation is an important methyl group donor?

Correct AnswerverifiedShow Answer

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Which of the following is a product of the transamination of aspartate and $\alpha$ -ketoglutarate?

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This is a...
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This 26S proteasome is composed of a 20S...
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alanine or...
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It is synthesized in...
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Serine dehydratase catalyzes the conversion of serine into NH₄⁺ and __________________.

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