✭ DNA & RNA structure

• • Both DNA and RNA are polymers that are made up of many repeating units called nucleotides
  • Each nucleotide is formed from:
  • A pentose sugar 
  • A nitrogen-containing organic base
  • A phosphate group
• • The components of a DNA nucleotide are:
  • A deoxyribose sugar
  • A phosphate group
  • One of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or thymine(T)
• The components of an RNA nucleotide are:

  • A ribose sugar
  • A phosphate group
  • One of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or uracil (U)
• • DNA and RNA are polymers (polynucleotides), meaning that they are made up of many nucleotides joined together in long chains
• • Separate nucleotides are joined via condensation reactions
  • These condensation reactions occur between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide
• A condensation reaction between two nucleotides forms a phosphodiester bond
• • It is called a phosphodiester bond because it consists of a phosphate group and two ester bonds (phosphate with double bond oxygen attached - oxygen - carbon)
• • The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as the sugar-phosphate backbone (of the DNA or RNA molecule)