Chapter 14: Translation and Proteins
Which of the following molecules is not found in a tRNA molecule?
Which sequence is found at 3' end of all tRNAs?
The process of tRNA “charging” does not involve
A tRNA synthetase recognizes an amino acid and all of its cognate tRNAs. What is another term for different tRNAs that accept the same amino acid?
Which of the following statements is true of each aminoacyl tRNA that enters the ribosome to participate in protein synthesis?
The incoming aminoacyl tRNA is guided to the A site by release factors (RFs).
The incoming aminoacyl tRNA binds to the A site, and the growing polypeptide chain in transferred to this aminoacyl tRNA in the A site.
The incoming aminoacyl tRNA is ejected from the A site after the amino acid is transferred.
The aminoacyl tRNA initially binds to the P site.
Which term describes the three condons (UGA, UAA, and UGA) that do not code for an amino acid and do not have a corresponding tRNA?
Polyribosomes consist of
One mRNA, several tRNAs, and several ribosomes
One mRNA and several ribosomes
Which of the following components binds first to mRNA during the assembly of the translation complex?
The large ribosomal subunit
The small ribosomal subunit
Which compound accumulates in the metabolic disorder alkaptonuria?
A mutation is induced in Neurospora that causes the loss of function of an enzyme essential to the biosynthesis of the vitamin pyridoxine. On which medium will such organisms not grow?
Minimal + all vitamins
Minimal + pyridoxine
Which level of protein structure do beta-pleated sheets and alpha helices represent?
Occasionally, a mutation is discovered that suppresses termination and allows a chain-terminating condon to be read as an amino acid code without changing the condon. What would be most likely effect of such a mutation?
They change the anticondon sequence for an amino acid-carrying tRNA.
They change the ribosome binding capacity.
They alter a terminating tRNA so that it carries an amino acid.
They cause a release factor to allow the polypeptide to be released.
Ribosomal RNAs in Eukaryotes and prokaryotes differ in all of the following ways except
Location in cell
Size of subunits
Number of proteins associated with ribosomes
Which of the following statements about ribosomal RNA (rRNA) is false?
There are several copies of each ribosomal RNA (rRNA).
The rRNA genes are clustered in both prokaryotes and eukaryotes.
There are multiple copies of the rRNA genes in both prokaryotes and eukaryotes.
Ribosomal RNAs are processed in both prokaryotes and eukaryotes.
Which of the following statements about translation is true?
The ribosome moves down the mRNA in the 3' to 5' direction and synthesizes protein in the direction of amino terminus to carboxy terminus.
The ribosome moves down the mRNA in the 5' to 3' direction and synthesizes protein in the direction of amino terminus to carboxy terminus.
The ribosome moves down the mRNA in the 3' to 5' direction and synthesizes protein in the direction of carboxy terminus to amino terminus.
The ribosome moves down the mRNA in the 5' to 3' direction and synthesizes protein in the direction of carboxy terminus to amino terminus.
Which of the following statements about translation in eukaryotes is true?
Eukaryotes have coupled transcription and translation, so the ribosome may bind the nascent mRNA as soon as the 5' end is made.
All proteins start with the modified amino acid formylmethionine (f-met).
In eukaryotes, a given mRNA produces only one type of polypeptide chain.
Ribosomes bind to the ribosome binding sequence (RBS) near the 5' end of mRNA.
Which of the following outcomes does not occur as a result of posttranslational modifications of a protein?
Removal of N-terminus amino acid
Addition of phosphate groups
Addition of metals to create tertiary or quaternary structures
Removal of introns
What knowledge can be gained from an understanding of a protein’s function that cannot be deduced by the DNA sequence of the gene that encodes the protein alone?
The DNA sequence of the protein
The amino acids that make up the protein
An understanding of biochemical pathways involving the protein
The presence of a point mutation
Which region of a tRNA molecule binds to amino acids?
The 5’ end
The 3’ end
Which of the following statements best describes the function of aminoacyl tRNA synthetase?
It provides the energy required to attach a specific amino acid to a tRNA molecule.
It synthesizes tRNA molecules.
It helps tRNA synthesize proteins.
It attaches a specific amino acid to a tRNA molecule.
At which site does the charged initiator tRNA bind during protein synthesis?
What event occurs during translocation?
mRNA shifts in the 5' direction along ribosome.
The two ribosomal subunits join to form a complex.
The polypeptide is cleaved from the terminal tRNA.
Amino acids are added to the polypeptide chain.