Question

Which of the following statement with respect to protein synthesis is true?

• A. tRNA molecules specific for particular amino acids are synthesized along an mRNA template in the cytoplasm.
• B. Amino acids read the mRNA sequence and with the help of peptidyl transferase polypeptide chain is formed.
• C. 28S rRNA acts as a ribozyme during protein synthesis and helps join the adjacent amino acids by forming the peptide bond in bacteria.
• D. mRNA synthesised on a DNA template, provides information that determines the sequence in which amino acids will be linked during translation.

Answer 1

The correct option is D mRNA synthesised on a DNA template, provides information that determines the sequence in which amino acids will be linked during translation.

The information from one of the strands of DNA is copied to mRNA by a process known as transcription. The sequence of bases in the mRNA thus formed define the order and sequence of amino acids in a polypeptide .These bases are read in triplet by ribosomes during translation. The triplet are called codons. Each codon codes for an amino acid.

tRNA present in the cytoplasm gets charged. During the charging of tRNA, ATP activates the amino acids and links it to the respective tRNA.

Based on the codon read by the ribosome on mRNA , a corresponding amino acid is brought to the site of protein synthesis by tRNA.

The amino acids then form a peptide bond. This process is catalysed by peptidyl transferase enzyme.

In bacteria 23S rRNA, which is a constituent of ribosomes also acts as an enzyme (ribozyme) catalysing the peptide bond formation.