Question

Describe the process of translation in Protein synthesis

Answer 1

The protein synthesis occurs in two steps, namely transcription and translation. During transcription, the information from DNA is encoded into mRNA. During translation, the mRNA works with a ribosome and tRNA to synthesize proteins.

Transcription takes place in the nucleus. During transcription, DNA partially unwinds by the enzyme helicase. This results in the single nucleotide chain to be copied. RNA polymerase reads the DNA strand from the 3' to 5' direction and synthesizes the complementary strand of messenger RNA in the 5' to 3' direction. The DNA strand which is transcribed is called as the template strand. The nucleotides on the RNA strand are complementary to the nucleotides on the DNA strand. DNA cytosine pairs with RNA guanine, DNA guanine pairs with RNA cytosine, DNA thymine pairs with RNA adenine and DNA adenine pairs with RNA uracil. After mRNA is synthesized, it is transported to the cytoplasm where it binds with ribosomes. Ribosomes are the sites of protein synthesis. Ribosomes have three important binding sites, one for mRNA and two (A site and P site) for tRNA. The start codon methionine occupies the P site and the second codon occupies the A site. The tRNA molecule whose anticodon is complementary to the mRNA forms a base pair with the mRNA in the A site. A peptide bond is formed between the amino acid attached to the tRNA in the A site and the methionine in the P site. The ribosome then slides down the mRNA in such a way that the tRNA in the A site moves to the P site and a new codon occupies the A site. This process continues until one of the three stop codons occupies the A site. At that point, the protein chain connected to the tRNA in the P site is released and the translation is complete.