DNA & RNA

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  • DNA & RNA
    • DNA & RNA function
      • DNA stores genetic information
      • RNA transfers genetic information from DNA to ribosomes
        • Ribosomes read RNA to make polypeptides - proteins
    • Nucleotide Structure
      • Molecules of DNA & RNA are polymers of nucleotides
      • Type of biological molecule that is made from 3 components
        • Pentose sugar
        • Nitrogen-containing organic base
        • Phosphate group
      • Monomers
    • Polynucleotide Structure
      • Many nucleotides join together to form polynucleotides
      • Nucleotides join up via condensation reaction between phosphate group of 1 & sugar of another
        • Forms phosphodiester bond
        • chain is known as sugar phosphate backbone
    • DNA structure
      • Double-helix structure
        • 2 separate strands wind around each other to form spiral
          • Strands are polynucleotides
            • made up of lots of nucleotides joined in long chain
      • DNA molecules are really long & coiled up very tightly
      • DNA nucleotide structure
        • made from phosphate group, pentose sugar deoxyribose & nitrogen-containing organic base
        • each has same sugar & phosphate
          • base on each can vary though
            • 4 possible bases
              • adenine
              • thymine
              • cytosine
              • cytosine
      • complementary base pairing
        • 2 DNA polynucleotide strands join by hydrogen bonds between bases
          • each base can only pair with 1 particular partner
            • adenine always with thymine
              • 2 hydrogen bonds form between
            • cytosine always with guanine
              • 3 hydrogen bonds form between
            • always equal amounts of A & T and C & G
        • 2 polynucleotide strands are antiparallel - run in opposite directions
          • 2 antiparallel strands twist to form DNA double helix
    • RNA Structure
      • made of nucletodies that contain a sugar, a phosphate group & 1 of 4 bases
        • nucleotides form polynucleotide strand with sugar-phosphate backbone
      • sugar in RNA nucleotides is ribose sugar
      • Uracil replaces thymine as a base
      • nucleotides form single polynucleotide strand
      • RNA strands are much shorter than most DNA polynucleotides

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