Chapter 17 Review: Gene Expression

 A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

• 3' UCA 5'. 
•  3' UGA 5'.
• 5' TCA 3'. 
• 3' ACU 5'

Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression? 

• mRNA, tRNA, and rRNA are transcribed
• RNA polymerase binds to the promoter.
• A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. 
•  Transcription can begin as soon as translation has begun even a little. 

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? 

• the protein product of the promoter 
• start and stop codons 
• ribosomes and tRNA 
• several transcription factors (TFs) 

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that 

• many noncoding stretches of nucleotides are present in mRNA. 
• there is redundancy and ambiguity in the genetic code. 
• many nucleotides are needed to code for each amino acid. 
•  there are termination exons near the beginning of mRNA.

 Which of the following is the first event to take place in translation in eukaryotes? 

• elongation of the polypeptide 
• base pairing of activated methionine-tRNA to AUG of the messenger RNA 
•  binding of the larger ribosomal subunit to smaller ribosomal subunits 
• the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

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

• It might result in a chromosomal translocation.
• It might exchange one stop codon for another stop codon. 
• It might exchange one serine codon for a different serine codon. 
• It might substitute an amino acid in the active site. 

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NGSS.HS-LS1-1

NGSS.HS-LS3-2

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 deletion of a codon 
• a deletion of two nucleotides 
• a substitution of the third nucleotide in an ACC codon 
•  a substitution of the first nucleotide of a GGG codon 

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NGSS.HS-LS3-2

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

• It changes an amino acid in the encoded protein.
• It has no effect on the amino acid sequence of the encoded protein.
• It introduces a premature stop codon into the mRNA.
•  It alters the reading frame of the mRNA. 

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NGSS.HS-LS1-1

 A frameshift mutation could result from 

• a base insertion only.
• a base deletion only. 
• a base substitution only. 
• either an insertion or a deletion of a base.

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NGSS.HS-LS3-2

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

• a base substitution 
• a base deletion near the start of a gene 
• a base deletion near the end of the coding sequence, but not in the terminator codon 
• deletion of three bases near the start of the coding sequence, but not in the initiator codon 

Tags

NGSS.HS-LS3-2