A1.2 Nucleic acids

• DNA


  is a nucleic acid
• 4 Types of biological molecules


  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Function of nucleic acids

  • Passes information between generations
  • DNA replication, information stores in DNA is passed from cell to cell through generations
  • DNA is a molecule of heredity in all living organisms
• Sequence of nitrogenous bases in nucleic acids


  Forms gene expression
• DNA has a limitless capacity to store information
• Types of nucleic acids

  • DNA - Deoxyribonucleic acids
  • RNA - Ribonucleic acids
• DNA


  • Passes hereditary information between generation of cells
  • Coded for making RNA during transcription
• RNA


  • Coded for making proteins during transcription
  • mRNA,rRNA,tRNA are the 3 main types of RNA involved in protien synthesis
• DNA is universal to life
• Although RNA is hypothesized to be the first genetic material to evolve, TODAY, all living organisms use DNA as the genetic material
• The use of the genetic code across all forms of life is evidence of universal common ancestry of life
• The sequences of DNA in cells can be analyzed and compared to determine evolutionary relationships between organisms
• The more similar the sequence, the more closely related the organisms
• Nucleic acids


  Polymers of nucleotide
• Nucleotide


  Considered the 'monomer' of nucleic acids 'polymer'
• Parts of a nucleotide

  • A Purine or Pyrimidine *nitrogenous base
  • A 5 carbon 'pentose' sugar (Ribose or deoxyribose)
  • Negatively charged phosphate group (PO-4)
• Pentose sugars


  Both ribose and deoxyribose are pentose sugars, a type of monosaccharides
• DNA nucleotide


  Deoxyribose sugar
• RNA nucleotide


  Ribose sugar
• Difference between ribose and deoxyribose

  Off carbon-2
• Nucleic acid backbone


  DNA and RNA have a "backbone" of phosphate-sugar- phosphate-sugar-phosphate…
• 5' and 3' ends of the backbone

  • 5' end with a phosphate
  • 3' end with a pentose
• Nucleic acid condensation reaction


  1. The backbone is formed when nucleotides combine

  2. A condensation reaction is a type of chemical reaction in which two molecules are combined to form a single molecule, with the loss of a water molecule
• DNA backbone


  Two sugar-phosphate backbones that run antiparallel to each other and twist together in a helical shape
• RNA backbone


  One sugar-phosphate backbone, but the molecule can twist and bind to itself depending on the type of RNA
• Nucleic acid backbone


  • The sharing of electrons in the covalent bond between sugar and phosphate provides strength to the structure
  • This strength maintains the nucleotides in their specific sequence, which is necessary for the storing, replication and expression of genetic information
• Nitrogenous Bases


  • All 5 of the nitrogenous bases contain nitrogen atoms
  • Based on the number of chemical rings in their structure, the nitrogenous bases are grouped as either purine or pyrimidine
• Sequence of bases


  Forms a code for storing genetic information in all living organisms
• Gene


  A specific sequence of nitrogenous bases in DNA nucleotides that codes for the making of a protein
• Decoding a gene


  1. Transcription

  2. Translation
• RNA


  • A polymer of nucleotides
  • Consists of one chains of nucleotides with one of four different nitrogenous bases
• RNA backbone


  As with DNA, RNA has a "backbone" of phosphate-sugar- phosphate-sugar-phosphate…
• RNA condensation reactions


  1. The RNA backbone is formed when nucleotides combine in a condensation reaction

  2. The 5' phosphate group on one nucleotide forms a new covalent bond with the 3' carbon on the ribose of the next nucleotide
• In this way, during transcription RNA is built from 5' to 3'
• DNA


  A nucleic acid that consists of two chains of nucleotides with one of four different nitrogenous bases
• DNA "Backbone"


  Each strand has a "backbone" of phosphate-sugar- phosphate-sugar-phosphate…
• DNA Condensation Reaction


  1. The DNA backbone is formed when nucleotides combine in a condensation reaction

  2. The 5' phosphate group on one nucleotide forms a new covalent bond with the 3' carbon on the deoxyribose of the next nucleotide
• In this way, during replication DNA is built from 5' to 3'
• DNA Double Helix


  Two backbones will hydrogen bond together to create a double helix
• Antiparallel


  The two different strands of the DNA double helix run in opposite directions