Question 1

Translation is initiated at the ____.
A) AUG codon
B) UAG codon
C) anticodon
D) promoter
E) downstream sequence

Accepted Answer

The AUG codon serves as the start codon for translation in both prokaryotes and eukaryotes, signaling the beginning of the protein-coding sequence in mRNA.

Question 2

Binding of the appropriate aminoacyl-tRNA to the A site requires:
A) no energy input
B) energy supplied by two ATP molecules
C) energy supplied by GTP
D) activation of the A site
E) phosphorylation of the tRNA molecule

Accepted Answer

The binding of the appropriate aminoacyl-tRNA to the A site of the ribosome requires energy supplied by GTP (guanosine triphosphate), not ATP. This process involves the hydrolysis of GTP to GDP and Pi, providing the necessary energy for the accurate positioning and binding of the aminoacyl-tRNA.

Question 3

Mobile genetic elements, such as transposons and retrotransposons, are significant because:
A) the entire human genome is composed of transposons.
B) they are present in the human genome, but not in the genomes of other organisms.
C) mutations caused by retrotransposons contribute greatly to a species' evolution.
D) transposons are the only mechanisms of genetic diversity.
E) only corn contain transposons.

Accepted Answer

Mutations caused by retrotransposons can contribute significantly to a species' evolution by introducing genetic variability. This variability can lead to new traits or adaptations that may be beneficial for survival and reproduction.

Question 4

tRNA molecules are able to act as adapters between amino acids and mRNA during translation because:
A) tRNA binds to ribosomes.
B) tRNA can bind to both mRNA and an amino acid.
C) tRNA anticodons bind to amino acids.
D) tRNA is recognized by RNA polymerase.
E) tRNA molecules bind to promoter sequences to initiate transcription.

Accepted Answer

tRNA molecules serve as adapters in protein synthesis by having an anticodon region that pairs with a complementary codon on mRNA and another site that attaches to a specific amino acid. This dual binding capability allows tRNA to translate the nucleotide sequence of mRNA into a sequence of amino acids.

Question 5

The process in which RNA is synthesized using a DNA template is called translation.

Accepted Answer

The process in which RNA is synthesized from a DNA template is called transcription. Translation is the process by which proteins are synthesized from the mRNA template.

Question 6

Draw an overview of the flow of genetic information from DNA to protein in eukaryote and prokaryotes. Construct one drawing for eukaryotes and one for prokaryotes. Label all structures, molecules, processes, and cellular compartments.

Accepted Answer

The answer of Draw an overview of the flow of...

Question 7

A grouping of three nucleotides codes for one amino acid.

Accepted Answer

A codon, which is a sequence of three nucleotides in mRNA, specifies a single amino acid in the process of protein synthesis.

Question 8

Proteins synthesized in bacteria have which of the following at their amino terminal end?
A) N-formyl-methionine
B) N-acetyl-adenine
C) adenine triphosphate
D) the AUG codon
E) the UUU codon

Accepted Answer

Proteins synthesized in bacteria often start with N-formyl-methionine as the first amino acid, which is a modified form of the amino acid methionine, encoded by the start codon AUG in mRNA.

Question 9

Which of the following numbered events represents the correct sequence of events of prokaryotic translation initiation? 1) Large ribosomal subunit binds to initiation complex.
2) Initiation tRNA binds small ribosomal subunit.
3) Initiation complex binds to ribosome recognition sequence on mRNA.
A) 1 → 2 → 3
B) 1 → 3 → 2
C) 2 → 1 → 3
D) 2 → 3 → 1
E) 3 → 2 → 1

Accepted Answer

The correct sequence for prokaryotic translation initiation is: the initiation tRNA binds to the small ribosomal subunit, then the initiation complex (small subunit + initiation tRNA) binds to the ribosome recognition sequence on mRNA, and finally, the large ribosomal subunit binds to the initiation complex, forming the complete ribosome.

Question 10

A ____ mutation results in the conversion of a codon specifying an amino acid to a termination codon.
A) nonsense
B) frameshift
C) chromosomal
D) missense
E) silent

Accepted Answer

A nonsense mutation results in the conversion of a codon that originally specified an amino acid into a stop codon, leading to premature termination of the protein.

Question 11

One of the mRNA codons specifying the amino acid leucine is 5′-CUA-3′. Its corresponding anticodon is:
A) 5′-GAT-3′
B) 3′-AUC-5′
C) 3′-GAU-5′
D) 3′-GAT-5′
E) 5′-GAU-3′

Accepted Answer

The anticodon is complementary to the mRNA codon and is read in the 3' to 5' direction. The mRNA codon 5'-CUA-3' pairs with the anticodon 3'-GAU-5'.

Question 12

The template DNA strand is described as being parallel to the complementary RNA strand.

Accepted Answer

The template DNA strand is antiparallel to the complementary RNA strand, meaning they run in opposite directions (5' to 3' for RNA and 3' to 5' for DNA).

Question 13

The notion that the genetic code is universal suggests a common ancestor for all living organisms.

Accepted Answer

The universality of the genetic code among all living organisms supports the idea of a common ancestor, as it suggests that all life forms evolved from a single origin where this genetic code was established.

Question 14

What is the modern definition of a gene?
A) a DNA sequence that encodes a specific RNA or protein product
B) a DNA sequence that encodes a specific polypeptide
C) an RNA sequence that encodes a single polypeptide
D) a DNA sequence that encodes several proteins
E) a DNA sequence that encodes specific amino acids

Accepted Answer

The modern definition of a gene encompasses a DNA sequence that encodes a specific RNA or protein product, reflecting our understanding that genes can encode both proteins and various forms of RNA (e.g., mRNA, tRNA, rRNA, miRNA) that may not necessarily be translated into proteins.

Question 15

Frameshift mutations result from the:
A) substitution of one base pair for another
B) substitution of more than one base pair
C) insertion or deletion of one or two base pairs
D) substitution of a stop codon for an amino acid-specifying codon
E) substitution of a start codon for an amino acid codon

Accepted Answer

Frameshift mutations occur due to the insertion or deletion of one or two base pairs, which shifts the reading frame of the genetic code, altering the sequence of amino acids encoded by the gene.

Question 16

Retroviruses, such as RNA tumor viruses, use __________ to make DNA from their RNA genomes.
A) DNA polymerase
B) DNA-dependent RNA polymerase
C) RNA polymerase
D) primase
E) reverse transcriptase

Accepted Answer

Retroviruses use reverse transcriptase to synthesize DNA from their RNA genomes, a process that is the reverse of the usual flow of genetic information in cells (from DNA to RNA).

Question 17

List the differences in prokaryotic and eukaryotic mRNAs and explain the purpose of these differences.

Accepted Answer

The answer of List the differences in prokaryotic and eukaryotic...

Question 18

Compare DNA and RNA. Be sure to include differences in their chemical composition and structure and their roles within the cell.

Accepted Answer

The answer of Compare DNA and RNA. Be sure to...

Question 19

A mutation that replaces one amino acid in a protein with another is called a ____ mutation.
A) frameshift
B) recombinant
C) nonsense
D) missense
E) neutral

Accepted Answer

A missense mutation is when a single nucleotide change results in the substitution of one amino acid for another in the protein produced.

Question 20

Linus Pauling proposed the one gene - one enzyme hypothesis.

Accepted Answer

The one gene-one enzyme hypothesis was proposed by George Beadle and Edward Tatum, not Linus Pauling.

Quiz 13: Gene Expression

Translation is initiated at the ____.

Binding of the appropriate aminoacyl-tRNA to the A site requires:

Mobile genetic elements, such as transposons and retrotransposons, are significant because:

tRNA molecules are able to act as adapters between amino acids and mRNA during translation because:

The process in which RNA is synthesized using a DNA template is called translation.

Draw an overview of the flow of genetic information from DNA to protein in eukaryote and prokaryotes. Construct one drawing for eukaryotes and one for prokaryotes. Label all structures, molecules, processes, and cellular compartments.

A grouping of three nucleotides codes for one amino acid.

Proteins synthesized in bacteria have which of the following at their amino terminal end?

Which of the following numbered events represents the correct sequence of events of prokaryotic translation initiation? 1) Large ribosomal subunit binds to initiation complex. 2) Initiation tRNA binds small ribosomal subunit. 3) Initiation complex binds to ribosome recognition sequence on mRNA.

A ____ mutation results in the conversion of a codon specifying an amino acid to a termination codon.

One of the mRNA codons specifying the amino acid leucine is 5′-CUA-3′. Its corresponding anticodon is:

The template DNA strand is described as being parallel to the complementary RNA strand.

The notion that the genetic code is universal suggests a common ancestor for all living organisms.

What is the modern definition of a gene?

Frameshift mutations result from the:

Retroviruses, such as RNA tumor viruses, use __________ to make DNA from their RNA genomes.

List the differences in prokaryotic and eukaryotic mRNAs and explain the purpose of these differences.

Compare DNA and RNA. Be sure to include differences in their chemical composition and structure and their roles within the cell.

A mutation that replaces one amino acid in a protein with another is called a ____ mutation.

Linus Pauling proposed the one gene - one enzyme hypothesis.