DQ 3.8 CH 17

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'.

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

• A gene from an organism can theoretically be expressed by any other organism.

• All organisms have experienced convergent evolution.

• DNA was the first genetic material.

• The same codons in different organisms translate into the different amino acids.

11) 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.

Alternative RNA splicing

• is a mechanism for increasing the rate of transcription.

• can allow the production of proteins of different sizes from a single mRNA.

• can allow the production of similar proteins from different RNAs.

• increases the rate of transcription.

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?

• The mRNA could not exit the nucleus to be translated.

• The cell recognizes the absence of the tail and polyadenylates the mRNA.

• The molecule is digested by restriction enzymes in the nucleus.

• The molecule is digested by exonucleases since it is no longer protected at the 5' end.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

• TTT.

• UUA.

• UUU.

• AAA.

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.

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

• a base-pair substitution.

• a nucleotide mismatch.

• a frameshift mutation.

• a polypeptide missing an amino acid.

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

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

• Translation can begin while transcription is still in progress.

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

• Translation requires antibiotic activity.

A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?

• an accumulation of A and no production of B and C

• an accumulation of A and B and no production of C

• an accumulation of B and no production of A and C

• an accumulation of B and C and no production of A