Central Dogma

• Central Dogma


  Describes the flow of genetic information within a cell
• Central Dogma


  1. DNA Replication

  2. DNA Transcription

  3. RNA Translation
• DNA Replication


  • Produces two identical copies of DNA from a single original DNA molecule
  • Makes more DNA
  • Occurs in the nucleus (eukaryotic cell)
  • Happens before a cell divides so that the new daughter cell can also get a copy of DNA
  • Happens before mitosis or meiosis (eukaryotic cell) in a time known as interphase
• DNA Replication


  1. Double Helix Unwinding

  2. Base Pairing

  3. Semi-conservative Replication

  4. Cellular Proofreading
• Double Helix Unwinding


  The double-stranded DNA unwinds, and each separated strand acts as a template for replicating a new partner strand
• Double Helix Unwinding


  • DNA strands are bound with SSB (single-stranded binding) proteins to keep them separated
  • Topoisomerase keeps the DNA from supercoiling
• Base Pairing


  Nucleotides (A, T, C, and G) match up to synthesize the new partner strands, forming two new double helices
• Semi-conservative Replication


  Each new helix consists of an original DNA strand and a newly synthesized strand
• Cellular Proofreading


  Mechanisms ensure near-perfect fidelity during DNA replication (thanks to DNA polymerase)
• Enzymes


  • Helicase (the unzipping enzyme)
  • DNA Polymerase (the builder)
  • Primase (the initializer)
  • Ligase (the gluer)
• Helicase


  Unzips the two strands of DNA and breaks through the hydrogen bonds that hold DNA bases together
• DNA Polymerase


  Replicates DNA molecules to build a new strand of DNA
• Primase


  Helps DNA polymerase figure out where to get started using a primer, made of RNA
• Ligase


  Glues DNA fragments together and fills in the gaps between Okazaki fragments in the lagging strand (goes from 5' to 3')
• DNA Transcription


  Part of protein synthesis, making of protein (involved in transport, structure, acting as enzymes, protecting the body, etc.) from DNA
• DNA Transcription


  DNA -> RNA -> Protein
• DNA Transcription


  Process by which DNA gets converted into mRNA (messenger RNA)
• DNA Transcription


  DNA polymerase connects complementary RNA bases to the DNA that are bonded together to form mRNA (messenger RNA)
• DNA Transcription


  mRNA can then go out of the nucleus into the cytoplasm where it's going to attach to a ribosome
• RNA Translation


  Part of protein synthesis that happens after transcription, process of converting the information stored in mRNA and using it to build protein
• RNA Translation


  • In the cytoplasm, there are tRNA molecules (transfer RNA) that carry an amino acid (monomer of protein) on them
  • tRNAs are looking for complementary bases then transfer their amino acid (held together by a peptide bond)
  • Reads the bases as they transfer amino acids, represented by codons (in threes), specifically anticodons
• Methionine


  Considered a start codon as it is typically your first amino acid
• Stop codon


  Indicates that the protein building is finished