Ch. 15 Part 3: Translation Q's

How did the A site of the ribosome get its name?

• It is where AA are affixed to tRNAs, producing aminoacyl tRNAs.

• It is where the amino group on the growing polypeptide chain is available for peptide bond formation.

• It is the site occupied by incoming aminoacyl tRNAs.

• It is surrounded by alpha helices of ribosomal proteins.

How did the P site of the ribosome get its name?

• It is where the promoter resides.

• It is the site where peptide bond formation takes place.

• It is where peptidyl tRNAs reside.

• It is the site where the growing polypeptide chain is phosphorylated.

1.What is an anticodon?

• The part of an RNA message that signals the termination of translation.

• The part of a tRNA that binds to a complementary codon in mRNA.

• The part of a tRNA that accepts an AA, via a reaction catalyzed by tRNA synthetase.

• The part of an RNA message that signals the start of translation.

The job of a ribosome during translation can best be described as—

• targeting proteins to the rough ER

• determining the sequence of amino acids

• carrying amino acids to the mRNA

• catalyzing peptide bond formation between amino acids

Q5: What is the function of the signal sequence?

Answer to Q5 "What is the function of the signal sequence?"

Answer: The signal sequence (aka signal recognition particle (SRP) is an adaptor molecule between the ribosome and the ER. It allows ribosomes to switch from being free in the cytosol to the ER. When docked to the ER, the protein is modified and moved elsewhere in cell.

Q7: According to the wobble rules, the correct AA can be added to a growing polypeptide chain even if the third base in an mRNA codon does not correctly match the corresponding base in a tRNA anticodon. How do the wobble rules relate to the redundancy of the genetic code?

Answer to Q7: "According to the wobble rules, the correct AA can be added to a growing polypeptide chain even if the third base in an mRNA codon does not correctly match the corresponding base in a tRNA anticodon. How do the wobble rules relate to the redundancy of the genetic code?"

Answer: If the first two amino acids are the same and the last one changes, you have four possible codons that would code for the same amino acids.

Q9: What are the functions of the ribosome in polypeptide synthesis?

Answer to Q9: "What are the functions of the ribosome in polypeptide synthesis? "

Answer: It provides a site for the aminoacyltRNAs to come in with the AA an form bonds between the AA it carries with other tRNAs.