Question 1

Where does translation take place?

Accepted Answer

A)   In the centriole
B)   In the nucleus
C)   Anywhere in the cell
D)   In the nucleolus
E)   In the cytoplasmF) C) and D)
G) B) and D)

Question 2

With absolutely no exception, all organisms utilize the same genetic code for the production of proteins.

Accepted Answer

A) True 
 B)False

Question 3

Describe the basic structure of an amino acid.

Accepted Answer

The structure consists of a ce...

Question 4

Part of a DNA gene sequence reads CAT. If a mutation occurs changing the T to A, will the final protein be affected?

Accepted Answer

Both CAT and CAA enc...

Question 5

What is the role of tRNA in translation?

Accepted Answer

A)   It catalyzes peptidyl transferase activity.
B)   It binds to an mRNA codon and carries the corresponding amino acid.
C)   It helps fold up the finished polypeptide chain.
D)   It couples an amino acid with aminoacyl-tRNA synthetase.
E)   It brings together two subunits of a ribosome.F) A) and D)
G) B) and C)

Question 6

Why is methionine the first amino acid to be added to every polypeptide chain?

Accepted Answer

Because the start codon, AUG, ...

Question 7

Why is it that a carrot plant can express a bacterial gene?

Accepted Answer

A)   Because the bacterial gene hijacks the carrot's cellular machinery
B)   Because of the degeneracy of the genetic code
C)   Because the genetic code is the same in both organisms
D)   Because of the wobble phenomenon
E)   A carrot cannot express a bacterial gene.F) None of the above
G) All of the above C

Question 8

In a gene sequence, the DNA codon for tryptophan experiences a mutation at the first base position, changing it to T. What will be the resulting amino acid?

Accepted Answer

A)   Arginine
B)   Tryptophan (no change) 
C)   Threonine
D)   Serine
E)   A stop codon will halt translation.F) B) and C)
G) A) and B)

Question 9

How did von Ehrenstein et al. demonstrate that the specificity of codon recognition lies in the tRNA molecule, not in the amino acid it carries?

Accepted Answer

In vitro, they chemically converted the ...

Question 10

How many naturally occurring amino acids are used by ribosomes to construct proteins?

Accepted Answer

A)   64
B)   10
C)   20
D)   46
E)   3F) B) and C)
G) B) and E)

Question 11

Ribozymes in the large ribosomal subunit catalyze peptidyl transferase activity during elongation. What is the immediate result?

Accepted Answer

A)   The tRNA in the P site falls off the ribosome.
B)   The ribosome shifts by one codon toward the 3' end of the mRNA.
C)   A new charged tRNA moves into the A site.
D)   The bond is broken between the tRNA at the P site and its amino acid, and a peptide bond is formed between this amino acid and the one attached to the tRNA in the A site.
E)   The elongation factor EF-Tu is recycled.F) B) and E)
G) All of the above D

Question 12

In the genetic code, when the first two nucleotides of a triplet are identical and the third letter is U or C, the codon always codes for the same amino acid.

Accepted Answer

A) True 
 B)False

Question 13

There are 64 sense codons in the genetic code and 61 different types of tRNA molecules.

Accepted Answer

A) True 
 B)False

Question 14

In eukaryotes, the AUG initiation codon is located in the ________ sequence.

Accepted Answer

A)   Shine-Dalgarno
B)   Pribnow
C)   Kozak
D)   Goldberg-Hogness
E)   KhoranaF) B) and D)
G) A) and C) C

Question 15

What signals the termination of translation?

Accepted Answer

A)   The ribosome reaches a start codon.
B)   The ribosome runs out of charged tRNAs.
C)   The ribosome reaches a stop codon.
D)   The ribosome reaches the end of the mRNA.
E)   The polypeptide chain folds into a protein.F) B) and E)
G) C) and E)

Question 16

Would a two-letter code with four different nucleotides be sufficient to encode the 20 amino acids found in cells? Why or why not? What does the three-letter code imply about the nature of the genetic code?

Accepted Answer

A two-letter code would only encode 16 (...

Question 17

A mutation causes a G to be inserted after the first base of the codon for tryptophan. How will this affect the growing polypeptide chain?

Accepted Answer

A)   It will not be affected.
B)   The reading frame will be shifted to the left, and the wrong amino acids will be added from this point on.
C)   There will be a single amino acid substitution.
D)   Elongation will stop prematurely.
E)   None of the aboveF) C) and E)
G) A) and C)

Question 18

Protein synthesis begins when ribosomes bind to the UGA codon.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following statements is correct?

Accepted Answer

A)   For every amino acid, there is one codon.
B)   For every codon, there is one amino acid.
C)   A codon may signify more than one amino acid.
D)   All of these are correct.
E)   None of these are correct.F) A) and E)
G) A) and B)

Question 20

What is the wobble hypothesis, and what implications does it have for base-pairing rules and selective pressure on codons?

Accepted Answer

The wobble hypothesis refers to the dege...

Exam 13: Regulation of Gene Expression in Eukaryotes

Where does translation take place?

Correct AnswerverifiedShow Answer

With absolutely no exception, all organisms utilize the same genetic code for the production of proteins.

Correct AnswerverifiedShow Answer

Describe the basic structure of an amino acid.

Correct AnswerverifiedThe structure consists of a ce...View AnswerShow Answer

Part of a DNA gene sequence reads CAT. If a mutation occurs changing the T to A, will the final protein be affected?

Correct AnswerverifiedBoth CAT and CAA enc...View AnswerShow Answer

What is the role of tRNA in translation?

Correct AnswerverifiedShow Answer

Why is methionine the first amino acid to be added to every polypeptide chain?

Correct AnswerverifiedBecause the start codon, AUG, ...View AnswerShow Answer

Why is it that a carrot plant can express a bacterial gene?

Correct AnswerverifiedC

In a gene sequence, the DNA codon for tryptophan experiences a mutation at the first base position, changing it to T. What will be the resulting amino acid?

Correct AnswerverifiedShow Answer

How did von Ehrenstein et al. demonstrate that the specificity of codon recognition lies in the tRNA molecule, not in the amino acid it carries?

Correct AnswerverifiedIn vitro, they chemically converted the ...View AnswerShow Answer

How many naturally occurring amino acids are used by ribosomes to construct proteins?

Correct AnswerverifiedShow Answer

Ribozymes in the large ribosomal subunit catalyze peptidyl transferase activity during elongation. What is the immediate result?

Correct AnswerverifiedD

In the genetic code, when the first two nucleotides of a triplet are identical and the third letter is U or C, the codon always codes for the same amino acid.

Correct AnswerverifiedShow Answer

There are 64 sense codons in the genetic code and 61 different types of tRNA molecules.

Correct AnswerverifiedShow Answer

In eukaryotes, the AUG initiation codon is located in the ________ sequence.

Correct AnswerverifiedC

What signals the termination of translation?

Correct AnswerverifiedShow Answer

Would a two-letter code with four different nucleotides be sufficient to encode the 20 amino acids found in cells? Why or why not? What does the three-letter code imply about the nature of the genetic code?

Correct AnswerverifiedA two-letter code would only encode 16 (...View AnswerShow Answer

A mutation causes a G to be inserted after the first base of the codon for tryptophan. How will this affect the growing polypeptide chain?

Correct AnswerverifiedShow Answer

Protein synthesis begins when ribosomes bind to the UGA codon.

Correct AnswerverifiedShow Answer

Which of the following statements is correct?

Correct AnswerverifiedShow Answer

What is the wobble hypothesis, and what implications does it have for base-pairing rules and selective pressure on codons?

Correct AnswerverifiedThe wobble hypothesis refers to the dege...View AnswerShow Answer

Correct Answer
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The structure consists of a ce...
View Answer

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Both CAT and CAA enc...
View Answer

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Because the start codon, AUG, ...
View Answer

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C

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In vitro, they chemically converted the ...
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D

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C

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A two-letter code would only encode 16 (...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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The wobble hypothesis refers to the dege...
View Answer