AP Bio 05.05 Quiz

This table shows the codons found in messenger RNA. Using this information, what sequence of nucleotides in the template strand of DNA could code for the polypeptide sequence Val-His-Thr?

**I think 3' CAT- GTA- TGG 5' **

Which of the following molecules are produced during transcription? (2 points) 1. Messenger RNA 2. Ribozymes 3. Ribosomal proteins

1. and 2. only

A triplet of bases in a template strand of DNA is 5' CAG 3'. What would be the corresponding codon for mRNA?

3' GUC 5'

A triplet of bases in the template strand of DNA is 5' AGT 3'. What would be the corresponding codon for mRNA?

3' UCA 5'

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

A poly-A tail is added to the 3' end of mRNA, and a cap is added to the 5' end.

What enzyme was most likely used to produce the molecule shown in the figure?

A restriction enzyme

A researcher needs to clone a particular DNA sequence to express the sequence and also modify the polypeptide product. Which of the following vectors would allow her to satisfy both of these requirements?

A yeast plasmid

Separating DNA fragments by gel electrophoresis is useful for which of the following?

All of the listed responses are correct.

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If an experimenter was able to stop the translation reaction at this point, which of the following would he be able to isolate?

An assembled ribosome with a polypeptide attached to the tRNA in the P site

The segment of DNA shown in this figure has restriction sites I and II, which create restriction fragments A, B, and C. If these fragments were separated by gel electrophoresis, which of the following best represents the expected results?

C | A| B|

A group of students has taken samples of their own cheek cells, purified the DNA, and used a restriction enzyme known to cut at zero, one, or two sites in the particular gene of interest to the students. What steps should they follow next, in order, to compare these genes?

Gel electrophoresis to sort the fragments, then a fluorescent probe for gene sequence

The "universal" genetic code is now known to have some exceptions. Which of the following, if true, would serve as one such exception?

If UGA, which is usually a stop codon, is found to code for an amino acid in some organisms

After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence?

Introns are removed and exons are spliced together.

Imagine that an error in transcription alters the formation of one single tRNA molecule within a cell. The altered tRNA still attaches to the same amino acid, but its anticodon loop has a different sequence, which binds to a different mRNA codon. What will be the effect on translation in this cell?

One altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.

A scientist needs to make complementary DNA (cDNA) from RNA. Which of the following would she use?

Reverse transcriptase

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

Several transcription factors (TF's)

A researcher has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following describes the most likely result of this change?

The amino acid methionine will not bind.

In an experimental situation, a student removes the 5' cap and poly-A tail from an mRNA molecule before inserting it into a eukaryotic cell. Which of the following would you expect to occur as a result of these modifications?

The molecule is digested by exonucleases because it is not protected at the 5' end.

Which of the following is a function of a signal peptide?

To translocate polypeptides across the ER membrane

The anticodon of a particular tRNA molecule is

complementary to the corresponding mRNA codon

After eukaryotic transcription occurs, mRNA undergoes several modifications before leaving the nucleus to take part in translation. One modification involves the cutting out of nonessential sections of mRNA and splicing together the remaining sections of mRNA necessary for translation. Which of the following mRNA sections are spliced together into the finished RNA molecule?

exons