Dna

• DNA


  The primary biomolecule in living organisms that normally stores genetic information
• The chemical nature of DNA was first studied in Germany when Friedrich Miescher analyzed pus cells


  1969
• Nucleic acids


  The two major molecules classified as DNA and RNA
• Friedrich Miescher


  • Born in Basel, Switzerland
  • Went to the University of Tübingen to study under Felix Hoppe-Seyler
  • Given the task of researching the composition of lymphoid cells
• DNA


  A polymer of repeating subunits called nucleotides
• Nucleotide

  • Consists of a phosphate group, a five-carbon sugar, and a cyclic nitrogenous base
• Types of nitrogenous bases in DNA

  • Adenine (A)
  • Cytosine (C)
  • Guanine (G)
  • Thymine (T)
• Nucleosides in DNA

  Deoxyadenosine, deoxyguanosine, deoxycytidine, and deoxythymidine
• Nitrogenous bases

  Classified into purines (adenine and guanine) and pyrimidines (cytosine and thymine)
• The nitrogenous bases are heterocyclic, consisting of carbon and nitrogen atoms
• 1. X-ray crystallography data of Rosalind Franklin and Maurice Wilkins revealed the helical nature of the DNA molecule
• Chargaff's rules


  • In organisms, the purine content is roughly equal to the pyrimidine content
  • The quantities of adenine and thymine are always equal, and the quantities of cytosine and guanine are always equal
• DNA double-helix


  • Linked to a twisted ladder, where the sugar-phosphate backbones represent the curving sides and the base pairs are the rungs
  • The spacing between base pairs is 3.32 Ả, with about 10 base pairs per turn of the double helix
• Hydrogen bonding


  An essential aspect of the DNA structure that allows two strands to come together chemically
• Chromatin


  A molecular complex of DNA and proteins
• Proteins in chromatin


  • Histone
  • Non-histone
• Non-histone proteins


  • One of their roles is to further organize the 30 nm fiber into larger metaphase chromosomes
• Amino acids


  Protein monomers
• Proteins are complex biomolecules that comprise up to 20 different types of subunits called amino acids
• Proteins constitute approximately 15% of living cells wet weight (70% weight contributed by water)
• Roles of proteins in cells

  • Enzymatic function
  • Structural
  • Storage
  • Bioluminescence
• Levels of protein structure

  • Primary
  • Secondary
  • Tertiary
  • Quaternary
• Primary structure


  The amino acid sequence as specified by the corresponding gene's nucleotide sequence
• Secondary structure


  The spatial orientation of the amino acid chains
• Tertiary structure


  The protein's overall folding in the three-dimensional space
• Quaternary structure


  The association of at least two polypeptide subunits
• Protein Data Bank 


  An enormous collection of the published experiments about the structures of biomolecules, particularly the proteins, DNA, and RNA