DNA and RNA

• both types of nucleic acid - found in all living cells and both carry information
• deoxyribonucleic acid is used to store genetic information - all the instructions needed to grow and develop from a fertilised egg to a fully grown adult
• ribonucleic acid is similar in structure to DNA

  • one of its main functions is to transfer genetic information from the DNA to ribosomes
• ribosomes are the body's protein factories - read the RNA to make polypeptides in the process of translation
• ribosomes themselves are made from RNA and proteins
• molecules of DNA and RNA are polymers of nucleotides
• a nucleotide is a biological molecule which is made from three components:

  • pentose sugar (sugar with 5 carbon atoms)
  • nitrogen-containing organic base (contains carbon)
  • phosphate group
• • many nucleotides join together to form a polynucleotide strand
  • nucleotides join up via condensation reactions between the phosphate group of one nucleotide and the sugar of another
  • this forms a phosphodiester bond (consisting of one phosphate group and 2 esters)
  • chain of phosphates and sugars = sugar-phosphate backbone