Translation is the RNAdirected synthesis of a polypeptide a

Translation is the RNA-directed synthesis of a polypeptide: a closer look What molecule is responsible for \"interpreting\" the series of codons along a mRNA transcript? What does this molecule do? How does the structure of this molecule help it do its job? What is an anti-codon? What does the anti-codon interact with? Accurate translation of the genetic message requires two recognition steps: What are these two recognition steps? What is \"wooble\"? How does the concept of wooble account for the redundancy of the genetic code? What are ribosomes? How do ribosomes facilitate the construction of a polypeptide chain? What is the E site? What is the A site? What is the P site? What do each of these sites do? (h)Explain in general terms how to build a polypeptide chain. Point mutations can affect protein structure and function. What is a point mutation, what are the various types of point mutations we considered and what are the possible outcomes of point mutations in gene coding regions? What is the significance of point mutations from an evolutionary perspective? How might small-scale mutations be beneficial?

Solution

17.4

A. tRNA molecule is responsible for deciphering the codons.

- The tRNA molecule is RNA molecule folded on itself to generate a secondary structure. The secondary structure of a tRNA molecule has a ribosome binding site, an amino acid binding site and an anticodon sequence complementary to the codon. The tRNA molecule binds to respective amino acid and gets charged. The charged tRNA molecule then transfers the amino acid to the ribosome and elongate the polypeptide chain.

B. Anticodon is a sequence on tRNA that is complementary to the codon on mRNA. The anticodon interacts with the codon due to complementarity.

-Accurate translation involves (i) binding of specific amino acid having a corresponding anticodon and then, (ii) binding of the anticodon on tRNA to the complementary sequence on mRNA

C. Each codon comprises of three nucleotides, out of which first two are crucial for the amino acid determination. However, the third nucleotide of codon is not that important and is called wobble base.

D. Ribosomes are cell organelles responsible for the protein synthesis in the cell. They are composed of RNA and proteins.

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