Double helix structure

• Protein synthesis


  The process by which cells make proteins
• Engineering method


  A method used to create or modify something
• Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) are found in all living things
• Protein


  A large molecule composed of one or more chains of amino acids
• Nucleic acids


  • They direct the synthesis, modification, and functions of the cell which direct the activities of every living thing
• Nucleotide


  The basic unit of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogen-containing base
• Nitrogen-containing bases


  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Nitrogen-containing bases


  • They have fused rings in their structure
  • They are either purines or pyrimidines
• Complementary base pairing


  Adenine (A) always pairs with thymine (T) and guanine (G) always pairs with cytosine (C)
• DNA structure


  1. Two strands

  2. Antiparallel orientation

  3. Sugar-phosphate backbone

  4. Hydrogen bonds between complementary base pairs
• 5' and 3' ends

  The 5' end has a phosphate group, the 3' end has a hydroxyl group
• The sequence of a DNA strand is always written in the 5' to 3' direction
• Nucleic acid


  Found in all living things, directs the synthesis, modification, and functions of proteins in the cell
• DNA


  Deoxyribonucleic acid, a nucleic acid
• RNA


  Ribonucleic acid, a nucleic acid
• Components of a nucleotide

  • Phosphate group
  • Sugar (deoxyribose or ribose)
  • Nitrogenous base
• DNA structure


  • Double helix
  • Antiparallel strands
  • Complementary base pairing (A-T, G-C)
  • Hydrogen bonding between base pairs
• 5' end


  End with phosphate group
• 3' end


  Opposite end of 5' end, with OH group
• DNA sequence is always written in the 5' to 3' direction
• RNA has a similar structure to DNA but with some differences (e.g. uses uracil instead of thymine)