Molecular Biology of the Gene

Molecular Biology of the Gene: Summary

Structure of Genetic Material

• DNA and RNA are nucleic acids formed from long chains of nucleotides.

• Nucleotides consist of:

  • Nitrogenous base

  • Five-carbon sugar

  • Phosphate group

• DNA contains deoxyribose; RNA contains ribose.

• DNA nitrogenous bases: Adenine (A), Cytosine (C), Thymine (T), Guanine (G).

• RNA nitrogenous base: Uracil (U) replaces Thymine.

DNA Structure

• DNA is a double-stranded helix.

• Strands are held together by hydrogen bonds between complementary bases (A-T, C-G).

DNA Replication

• Begins with the separation of DNA strands.

• Each strand serves as a template for new complementary strands.

• Follows a semiconservative model: each new helix consists of one old and one new strand.

• DNA polymerase synthesizes daughter strands; DNA ligase connects fragments.

• Replication occurs in two directions at multiple sites simultaneously.