Gen bio 5

• Purines


  Two ringed, heterocyclic nitrogenous compounds (Nine-membered double rings)
• Chargaff's Rule


  • Amount of guanine should be equal to the amount of cytosine and the amount of adenine should be equal to the amount of thymine
  • 1:1 stoichiometric ratio of purine and pyrimidine bases (i.e., A+G=T+C) should exist
• Discovery of DNA structure in 1953

  • X-ray diffraction work by Dr. Rosalind Franklin
  • Creation of the famous Photo 51 demonstrating the double-helix structure of DNA
  • Article "Genetical Implications of the Structure of Deoxyribonucleic Acid" written by James Watson and Francis Crick describing the double helical model for secondary structure of B-form of DNA
• DNA structure


  • Double helix structure composed of two complementary strands
  • Two DNA strands run antiparallel, where 3' end of one strand faces the 5' end of the other
• DNA sugar type


  Deoxyribose (C5H10O4)
• RNA


  • Has a hydroxyl (OH) group at position 2
  • Generally single-stranded, but there are special RNA viruses that are double-stranded
• RNA bases


  • Adenine (A)
  • Uracil (U)
  • Guanine (G)
  • Cytosine (C)
• RNA sugar type


  Ribose (C5H10O5)
• DNA Replication


  1. Unwinding - The old strands that make up the parental DNA molecule are unwound and unzipped

  2. Complementary Base Pairing - Nucleotides pair with each other (A-T, G-C)

  3. Joining - The complementary nucleotides paired with parent strands are connected to each other to form a chain
• Clone


  A collection of molecules or cells, all identical an original molecule or cell
• Cloning a gene


  • Making many copies of it, e.g., by replicating it in a culture of bacteria
  • Can be a normal copy (wild type) or an altered version (mutant)
• Recombinant DNA Technology


  • Makes manipulating genes possible
  • The process of making multiple, identical copies of a particular piece of DNA
• Transcription


  1. DNA information is converted into a messenger RNA (mRNA) molecule

  2. The DNA of a gene acts as a template for complementary base pairing

  3. The mRNA is "read" following the genetic code, which connects the DNA sequence to the amino acid sequence in proteins
• Translation


  1. The mRNA formed in transcription is transported out of the nucleus, into the cytoplasm, to the ribosome

  2. mRNA directs protein synthesis with the assistance of transfer RNA (tRNA)