Principles of Genetics and Breeding

1.2.3.10 Reading genetic information

1.2.3.10 Reading

• The DNA information specifying amino acids sequences is copied into m-RNA (messenger RNA). RNA is composed of a linear sequence of nucleotide like DNA, but it has two chemical differences.
• When DNA is copied into RNA, a specific region of the DNA helix exposes a stretch of single-stranded DNA that will act as a template for complementary base-pairing, i.e. A,T,G and C on DNA correspond to U,A,C and G on RNA respectively.
• This pairing is conducted by the RNA polymerase molecule until it encounters the termination signal in the DNA.
• The resulting m-RNA is released out of the nucleus, i.e. into the cell cytoplasm through nuclear pores.
• As a single m-RNA molecule is moved through the surface of a ribosome in the cell cytoplasm, it is then matched to complementary sets of three nucleotides in t-RNA molecules at which each amino acid is held, and this amino acid is added to the growing protein chain.
• For example, the triplet of nucleotides GTC is read as CAG on m-RNA molecule with glutamic acid. Genetic information in proteins and the process of protein synthesis can be well explained by the way of thinking described above and has been demonstrated.