Unit 3

• Replication Process


  1. Initiation

  2. Elongation

  3. Termination
• Transcription


  Process of synthesizing RNA from DNA
• DNA Fingerprinting


  Technique used to identify individuals by their unique DNA profiles
• Gene Therapy


  Treatment of genetic disorders by replacing, manipulating or supplementing nonfunctional genes
• DNA


  Deoxyribonucleic acid, a vitally important molecule for not only humans but also most other organisms
• DNA


  • Carries the instructions that make each person unique
  • Contains our hereditary material
  • Provides the instructions necessary for an organism to grow, develop, and reproduce
  • Is a double-stranded molecule, forming a 3-D structure called a double helix
  • The sequence of base pairs encodes the genetic information
• Protein Synthesis


  1. DNA provides the instructions

  2. The DNA sequence houses the information to make proteins

  3. Each group of three bases in DNA corresponds to specific amino acids

  4. First, the two DNA strands split apart

  5. Special proteins read the base pairs on a DNA strand to create an intermediate messenger molecule called mRNA

  6. mRNA travels outside the nucleus and serves as a message to cellular machinery that builds proteins

  7. Components of the cell read the mRNA's message three base pairs at a time and assemble a protein, amino acid by amino acid
• RNA


  Ribonucleic acid, a crucial molecule in biology
• Protein Synthesis (RNA)


  1. RNA carries the instructions from DNA to the cellular machinery responsible for building proteins

  2. Involves transcription (where RNA is synthesized from DNA) and translation (where RNA guides protein assembly)
• Types of RNA


  • Messenger RNA (mRNA)
  • Transfer RNA (tRNA)
  • Ribosomal RNA (rRNA)
• RNA Structure

  • RNA is typically single-stranded but can fold into complex shapes due to base pairing
  • Its structure allows for modifications (e.g., methylation) that influence gene expression
  • Unlike DNA, RNA contains uracil (U) instead of thymine (T)
• Roles of RNA Beyond Protein Synthesis


  • Regulation: Some RNA molecules regulate gene expression by binding to specific sequences
  • Catalysis: Ribozymes (RNA enzymes) can catalyze chemical reactions
  • Telomerase: An RNA component maintains telomeres, protecting chromosome ends
  • Viral Genomes: Some viruses use RNA as their genetic material
• Differences between DNA and RNA

  • Composition: DNA contains the sugar deoxyribose, while RNA contains the sugar ribose
  • Structure: DNA is a double-stranded helix, whereas RNA is usually a single-stranded helix
  • Bases: DNA uses the bases adenine (A), thymine (T), cytosine (C), and guanine (G), while RNA uses the bases adenine (A), uracil (U), cytosine (C), and guanine (G)
  • Function: DNA stores genetic information for the long term and transfers it to make other cells and new organisms, while RNA transfers genetic code from the nucleus to ribosomes for protein synthesis
  • Stability and Reactivity: DNA is stable under alkaline conditions and resistant to UV damage, while RNA is less stable and more reactive due to the O-H bond in ribose