Chapter 17

Last update by madeleine.solano-garretson on 12/08/2013
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28) Which of the following is the first event to take place in translation in eukaryotes?

A) elongation of the polypeptide

B) base pairing of activated methionine-tRNA to AUG of the messenger RNA

C) binding of the larger ribosomal subunit to smaller ribosomal subunits

D) covalent bonding between the first two amino acids

E) the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

Answer:
E) the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

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  • madeleine solano garretson
    Answered in Chapter 17

    29) The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following?

    A) polypeptide factors plus ATP

    B) polypeptide factors plus GTP

    C) polymerases plus GTP

    D) SRP plus chaperones

    E) signal peptides plus release factor

    B) polypeptide factors plus GTP


  • madeleine solano garretson
    Answered in Chapter 17

    30) What is the function of the release factor (RF)?

    A) It separates tRNA in the A site from the growing polypeptide.

    B) It binds to the stop codon in the A site in place of a tRNA.

    C) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond.

    D) It supplies a source of energy for termination of translation.

    E) It releases the ribosome from the ER to allow polypeptides into the cytosol.

    B) It binds to the stop codon in the A site in place of a tRNA.


  • madeleine solano garretson
    Answered in Chapter 17

    31) Why might a point mutation in DNA make a difference in the level of protein's activity?

    A) It might result in a chromosomal translocation.

    B) It might exchange one stop codon for another stop codon.

    C) It might exchange one serine codon for a different serine codon.

    D) It might substitute an amino acid in the active site.

    E) It might substitute the N-terminus of the polypeptide for the C-terminus.

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  • madeleine solano garretson
    Answered in Chapter 17

    32) Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

    A) a deletion of a codon

    B) a deletion of two nucleotides

    C) a substitution of the third nucleotide in an ACC codon

    D) a substitution of the first nucleotide of a GGG codon

    E) an insertion of a codon

    B) a deletion of two nucleotides


  • madeleine solano garretson
    Answered in Chapter 17

    33) What is the effect of a nonsense mutation in a gene?

    A) It changes an amino acid in the encoded protein.

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    C) It introduces a premature stop codon into the mRNA.

    D) It alters the reading frame of the mRNA.

    E) It prevents introns from being excised.

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  • madeleine solano garretson
    Answered in Chapter 17

    34) A frameshift mutation could result from

    A) a base insertion only.

    B) a base deletion only.

    C) a base substitution only.

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  • madeleine solano garretson
    Answered in Chapter 17

    35) Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein?

    A) a base substitution

    B) a base deletion near the start of a gene

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    D) deletion of three bases near the start of the coding sequence, but not in the initiator codon

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  • madeleine solano garretson
    Answered in Chapter 17

    36) The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in

    A) a base-pair substitution.

    B) a nucleotide mismatch.

    C) a frameshift mutation.

    D) a polypeptide missing an amino acid.

    E) a nonsense mutation.

    D) a polypeptide missing an amino acid.


  • madeleine solano garretson
    Answered in Chapter 17

    37) Which of the following statements is true about protein synthesis in prokaryotes?

    A) Extensive RNA processing is required before prokaryotic transcripts can be translated.

    B) Translation can begin while transcription is still in progress.

    C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.

    D) Translation requires antibiotic activity.

    E) Unlike eukaryotes, prokaryotes require no initiation or elongation factors.

    B) Translation can begin while transcription is still in progress.


  • madeleine solano garretson
    Answered in Chapter 17

    38) Of the following, which is the most current description of a gene?

    A) a unit of heredity that causes formation of a phenotypic characteristic

    B) a DNA subunit that codes for a single complete protein

    C) a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

    D) a DNA—RNA sequence combination that results in an enzymatic product

    E) a discrete unit of hereditary information that consists of a sequence of amino acids

    C) a DNA sequence that is expressed to form a functional product: either RNA or polypeptide