RQ Ch 17

A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be

3' AAA-GAA-TAA-CAA 5'

Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site. 2. A peptide bond forms between the new amino acid and a polypeptide chain. 3. tRNA leaves the P site, and the P site remains vacant. 4. A small ribosomal subunit binds with mRNA. 5. tRNA translocates to the P site.

4, 1, 2, 5, 3

A particular eukaryotic protein is 300 amino acids long. Which of the following could be the maximum number of nucleotides in the DNA that codes for the amino acids in this protein?

900

During translation, chain elongation continues until what happens?

A stop codon is encountered

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

ACU

What is a ribozyme?

An enzyme made up of RNA

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

It introduces a stop codon into the mRNA

Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because

RNA acts as an expendable copy of the genetic material, allowing the DNA to serve as a permanent, pristine repository of the genetic material

Which of the following is true for both prokaryotic and eukaryotic gene expression?

RNA polymerase binds to the promoter region to begin transcription.

RNA polymerase and DNA polymerase differ in that

RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.

Which of the above is analogous to a single substitution mutation?

THECATARETHERAT

Which of the above is analogous to a frameshift mutation?

THECATATTHERAT

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that

The rules for base pairing between the third base of a codon and tRNA are flexible (WOBBLE)

When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by

a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane

Which of the following helps to stabilize mRNA by inhibiting its degradation?

both C and D

What are ribosomes composed of?

both rRNA and protein

What are the coding segments of a stretch of eukaryotic DNA called?

exons

What are polyribosomes?

groups of ribosomes reading a single mRNA simultaneously

What type of bonding is responsible for maintaining the shape of the tRNA molecule?

hydrogen bonding between base pairs

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG

met-ser-ser-leu-ser-leu

If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for

proline

The dipeptide that will form will be

proline-threonine

Which of the following is not a part of the eukaryotic transcription initiation complex?

snRNP

Where is eukaryotic ribosomal RNA transcribed?

the nucleolus