Question

​​​​​​Please answer all the following questions completely about ribosome:

1. What is found in the active site of the ribosome, RNA bases or amino acids?

2. What type of interaction positions the tRNA prior to peptide bond synthesis.

3. Where is the next amino acid added, to N- or C-terminus of the growing chain?

4. What are the two steps after peptide bond formation?

Answer 1

The active site of the ribosome is built of RNA

tRNAs (transfer RNAs) carry amino acids to the ribosome. They act as "bridges," matching a codon in an mRNA with the amino acid it codes for.Ribosome has three slots for tRNAs: the A site, P site, and E site. tRNAs move through these sites (from A to P to E) as they deliver amino acids during translation.   It has three binding sites: A, P, and E sites. The A site binds to aminoacyl-tRNA (a tRNA with an amino acid). The P site is the site in a ribosome occupied by tRNA carrying the growing peptide chain (i.e. peptidyl tRNA). The E site is the site for decylated tRNA on transit out from the ribosome.

the next amino acid added, to C-terminus of the growing chain.The aminoacyl-tRNA with an anticodon complementary to the A site codon lands in the A site. A peptide bond is formed between the amino group of the A site amino acid and the carboxyl group of the most-recently attached amino acid in the growing polypeptide chain attached to the P-site tRNA.The formation of the peptide bond is catalyzed by peptidyl transferase, an RNA-based enzyme that is integrated into the large ribosomal subunit. The energy for the peptide bond formation is derived from GTP hydrolysis, which is catalyzed by a separate elongation factor.

Translation: Beginning, middle, and end

A book or movie has three basic parts: a beginning, middle, and end. Translation has pretty much the same three parts, but they have fancier names: initiation, elongation, and termination.

• Initiation ("beginning"): in this stage, the ribosome gets together with the mRNA and the first tRNA so translation can begin.

• Elongation ("middle"): in this stage, amino acids are brought to the ribosome by tRNAs and linked together to form a chain.

• Termination ("end"): in the last stage, the finished polypeptide is released to go and do its job in the cell.