Gen Bio Q1 Molecular Structure & Central Dogma

• Two type of nucleic acid

  Deoxyribonucleic acid (DNA) & Ribonucleic acid (RNA)
• DNA and RNA are made up of monomers known as

  nucleotides
• Nucleotides are made up of

  Nitrogenous base, pentose sugar, phosphate group
• Pentose sugars found in DNA is deoxyribose while the one found in RNA is ribose.
• The nitrogenous bases found in RNA are adenine, uracil, cytosine, guanine
• The nitrogenous bases found in DNA are adenine, thymine, cytosine, guanine
• The purpose of protein is for structure
• Nitrogenous base are made up of purine and pyrimidine
• Purine has two carbon-nitrogen rings and Pyrimidines has one carbon-nitrogen ring
• Difference with the sugars is the presence of hydroxyl in 2' of ribose and hydrogen on deoxyribose
• Adenine and Thymine forms two hydrogen bonds
• Guanine and Cytosine forms three hydrogen bonds
• Adenine and Guanine are classified as purine
• Cytosine, Thymine, and Uracil are classified as pyrimidines
• Three main type of RNA

  mRNA (messenger RNA)

  rRNA (ribosomal RNA)

  tRNA (transfer RNA)
• The mRNA carries information from DNA to the ribosome
• Amino acids are monomers that make up proteins
• Transcription


  A process where DNA is copied into a complementary RNA molecule
• Translation


  A process where RNA is translated into a sequence of amino acids, forming a protein
• Central Dogma


  A model that explains how genetic information flows from DNA to proteins
• Polypeptide Chain


  A linear sequence of amino acids linked together by peptide bonds
• Protein


  A fully folded and functional polypeptide chain with a specific 3D structure, giving it unique properties and functions
• Termination of DNA Replication

  • Replication ends when entire DNA molecule is copied
• Enzymes in Prokaryotic DNA Replication

  • DNA polymerase
  • Helicase
  • Ligase
  • Primase
  • Topoisomerase
• DNA polymerase


  Synthesizes new DNA strand
• Helicase


  Unwinds the DNA double helix
• Ligase


  Joins Okazaki fragments on the lagging strand
• Primase


  Synthesizes RNA primers
• Topoisomerase


  Relieves supercoiling
• Steps of Transcription

  1. Initiation

  2. Elongation

  3. Termination
• Steps of Translation


  1. Initiation

  2. Elongation

  3. Termination
• Steps of DNA Replication

  1. Initiation

  2. Elongation

  3. Termination
• DNA vs. RNA

  DNA is double-stranded; RNA is single-stranded
• Purine


  Double-ring structure (adenine and guanine)
• Pyrimidine


  Single-ring structure (cytosine, thymine, and uracil)
• Purines pair with pyrimidines


  A with T (or U in RNA) and G with C
• Types of Protein


  • Enzymes
  • Structural Proteins
  • Transport Proteins
  • Signal Proteins
  • Defensive Proteins
• Enzymes


  Catalyze biochemical reactions
• Structural Proteins


  Provide support and shape (e.g., collagen)
• Transport Proteins


  Carry substances (e.g., hemoglobin)