BiologyExchange.co.uk Shared Resource

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BiologyExchange.co.uk Shared Resource

  1. 1. Recap Nucleic acids
  2. 2. Chromosomes <ul><li>A chromosome consists of:- </li></ul><ul><ul><li>DNA </li></ul></ul><ul><ul><li>Coiled around protein balls </li></ul></ul>
  3. 4. DNA is a polymer <ul><li>The monomer is a nucleotide </li></ul>
  4. 5. 4 different bases
  5. 6. Nucleotides join together <ul><li>To form a chain </li></ul><ul><li>Sugar to phosphate to sugar to phosphate…. </li></ul><ul><li>Joined by strong covalent bonds </li></ul><ul><li>The chain twists to form a helix </li></ul>
  6. 7. Bases pair <ul><li>Bases on one strand of DNA pair with complementary bases on the other strand. A with T and C with G </li></ul><ul><li>Two chains join together to form a double helix </li></ul>
  7. 10. RNA <ul><li>We look at two forms:- </li></ul><ul><ul><li>Messenger RNA – mRNA </li></ul></ul><ul><ul><li>Transfer RNA – tRNA </li></ul></ul>
  8. 11. Differences between DNA and RNA <ul><li>The sugar in DNA is deoxyribose </li></ul><ul><li>The sugar in RNA is ribose </li></ul>
  9. 12. Differences between DNA and RNA <ul><li>The nitrogenous bases in DNA are Cytosine; Guanine; Adenine; Thymine </li></ul><ul><li>The nitrogenous bases in RNA are Cytosine; Guanine; Adenine; Uracil </li></ul>
  10. 13. Differences between DNA and RNA Shorter; Present in nucleus and cytoplasm; Short term; Some bases paired and some unpaired Longer; Only found in the nucleus; Long lasting; Many bases are paired RNA DNA
  11. 14. mRNA <ul><li>Single strand of nucleotides with no base pairing </li></ul>
  12. 15. tRNA <ul><li>Single strand that is twisted back on itself so that some areas have paired bases </li></ul>
  13. 16. tRNA
  14. 18. tRNA ‘clover leaf’ shape ; (allow reference to loop / folded structure) tRNA standard length ; tRNA has an amino acid binding site ; tRNA has anticodon available / three exposed bases ; tRNA has hydrogen bonds (between base pairs) ;

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