Question

Translocase is an enzyme required for

• A. DNA replication
• B. RNA synthesis
• C. Initiation of protein synthesis
• D. Protein synthesis and chain elongation

Answer 1

The correct option is D Protein synthesis and chain elongation

DNA replication is synthesis of daughter DNA strands using parental DNA as template. The process is carried out by DNA polymerase that polymerize deoxyribonuclotides by joining 5' phosphate group of one nucleotide unit to the 3'-hydroxyl group of the next nucleotide (phosphodiester linkage). RNA synthesis is the carried out by RNA polymerase enzyme which polymerize ribonucleotides using DNA strand as template. Binding of 60S ribosomal subunit to a complex of mRNA, 40S subunit and initiation factors marks the formation of initiation complex which in turn signals the beginning of translation. Translocation is the final step in elongation phase of protein synthesis. It involves movement of ribosome one codon toward the 3' end of the mRNA that shifts the anticodon of the dipeptidyl tRNA from the A site to the P site and shifts the deacylated tRNA from the P site to the E site which is then released into the cytosol. This process requires translocase which is also called EF-G and GTP. The correct option is D.