Nucleic Acids

• DNA is the genetic material of all living organisms
• 4 major types of biological molecules upon which life is based

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids
• Nucleic acids


  The information molecules of cells found throughout the living world
• Genetic code


  The code containing the information in nucleic acids
• The genetic code is universal, meaning that it is not specific to a few organisms or to just one group, but to all groups and species
• Functions of nucleic acids


  • Pass information between generations
  • Code for protein production
• Semi-conservative DNA replication


  Depends on the complementary base pairing of DNA
• Transcription


  The synthesis of RNA using a DNA template
• Translation


  The synthesis of a polypeptide from mRNA
• Types of nucleic acids


  • DNA - deoxyribonucleic acid
  • RNA - ribonucleic acid
• DNA


  • Passes heredity information between generations of cells
  • Codes for making RNA during transcription
• RNA


  • Codes for making proteins during translation
  • mRNA, rRNA, and tRNA are the three main types of RNA involved in protein synthesis
• Although RNA and DNA have some differences, both are polymers of nucleotides with a sugar-phosphate backbone
• The Hershey-Chase experiment determined that DNA is the genetic material passing from cell to cell through generations
• DNA is universal to life, although some viruses use RNA as their genetic material
• The biochemical similarity of all current life suggests that the last universal common ancestor (LUCA) of all life used DNA as the genetic material
• Nucleotide


  Composed of a nitrogenous base, a pentose sugar, and a phosphate group
• The type and sequence of nitrogenous bases in the nucleic acid polymer forms the basis of the genetic code
• The negative charge on the phosphate group allows DNA to be attracted to histone proteins in a nucleosome, allowing meters of DNA to fit inside a single cell
• Nitrogenous bases


  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
  • Uracil (U)
• Nucleotides are composed of a nitrogenous base, a pentose sugar, and a phosphate group
• Pentose sugars


  Both ribose and deoxyribose are pentose sugars, a type of monosaccharide
• The orientation of the carbon atoms determines the directionality of RNA and DNA, with implications for replication, transcription and translation

  
• DNA


  A polymer formed by condensation of deoxyribose nucleotides
• RNA


  A polymer formed by condensation of ribose nucleotides
• The difference between ribose and deoxyribose is off carbon-2
• Nucleic acid backbone


  A backbone of phosphate-sugar-phosphate-sugar-phosphate, with a 5' end and a 3' end
• Nucleic acid condensation reaction

  The 5' phosphate group on one nucleotide forms a new covalent bond with the 3' carbon on the pentose of the next nucleotide
• DNA double helix


  Two sugar-phosphate backbones that run antiparallel to each other and twist together

  
• RNA backbone


  One sugar-phosphate backbone that can twist and bind to itself, depending on the type of RNA
• The sugar-phosphate backbone of nucleic acids provides structural support and maintains the nucleotides in their specific sequence
• Nitrogenous bases


  Adenine (A), Thymine (T), Cytosine (C), Guanine (G), Uracil (U)
• The order of the different types of nucleotides serves as a code for storing genetic information in all living organisms
• Genetic code


  A group of three nucleic acid bases signifies for an amino acid
• All forms of life use the same genetic code, which is evidence of universal common ancestry
• Gene


  A specific sequence of nitrogenous bases in DNA nucleotides that codes for the making of a protein
• The diversity of possible gene sequences and lengths means there is limitless capacity of DNA for storing genetic information
• DNA Condensation Reaction


  1. 5' phosphate group on one nucleotide forms a new covalent bond with the 3' carbon on the deoxyribose of the next nucleotide

  2. DNA is built from 5' to 3' during replication
• DNA Double Helix


  • Two sugar-phosphate backbones
  • Backbones hydrogen bond together
  • Nitrogenous bases join together via hydrogen bonds

  
• Complementary base pairing


  • Adenine pairs with Thymine with two hydrogen bonds
  • Guanine pairs with Cytosine with three hydrogen bonds