DNA: The Molecule of Life

DNA Structure and Function

  • DNA (Deoxyribose Nucleic Acid) is a double helix molecule composed of nucleotides.

  • Nucleotides consist of a sugar, phosphate, and a base.

Base Pairing Rules

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

  • A pairs with T; G pairs with C (A-T, C-G).

DNA Replication

  • DNA replication is semi-conservative; each new DNA molecule has one original and one new strand.

  • DNA strands are complementary; the molecule unzips, serving as templates.

Protein Production

  • Genetic information flows from DNA to RNA (transcription) to protein (translation).

  • Transcription rewrites DNA code into mRNA, which exits the nucleus.

Translation Process

  • Ribosomes translate mRNA codons into amino acids to build proteins.

  • tRNA carries amino acids; anticodons match mRNA codons.

Gene Regulation

  • Gene expression is regulated at multiple levels, including transcription and translation.

  • Cell communication influences gene expression significantly.

Mutations and Cancer

  • Mutations (changes in DNA sequence) can be spontaneous or induced.

  • Mutations in proto-oncogenes can lead to cancer (unregulated cell growth).

Genetic Engineering

  • Genetic engineering manipulates DNA for practical purposes.

  • Includes techniques like PCR (Polymerase Chain Reaction) and creation of GMOs (genetically modified organisms).

Genomics and Gene Therapy

  • Genomics studies complete sets of genes; human genome contains ~21,000 genes.

  • Gene therapy aims to fix genetic diseases by correcting defective genes, but results can be variable.