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DNA Information

  • DNA stands for Deoxyribonucleic Acid.�
  • DNA Shape can be described as…
    • Spiral Staircase
    • Twisted Ladder
    • Double Helix�
  • DNA is antiparallel.
    • Strands run in opposite directions.�
  • DNA is complementary.
    • A and T are complements and fit together.
    • G and C are complements and fit together.�
  • DNA is different from one species to another because the order of bases (A, T, C, G) is different.
    • Just like 26 letters in the alphabet rearrange to make millions of words.

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DNA is also semi-conservative... Meaning that every time it

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DNA- Double Helix (twisted ladder)

  • Sides of ladder
      • Alternating sugar and phosphates.
  • Rungs of ladder (Nitrogen Bases)
      • A = Adenine
      • T = Thymine
      • C = Cytosine
      • G = Guanine

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DNA- Double Helix (twisted ladder)

  • DNA (nucleic acid) structure
    • Made up of smaller units (monomers) called nucleotides.
    • Nucleotide
      • One phosphate
      • One sugar (deoxyribose)
      • One nitrogen base (A, T, C, or G)

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DNA- Double Helix (twisted ladder)

DNA is Antiparallel!!!

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DNA REPLICATION

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  • What is it?
    • Making another copy of DNA.

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  • Where/When does it happen?
    • Occurs in the nucleus of the cell.
    • Done during synthesis of interphase.
    • Makes a copy of itself during mitosis and meiosis.

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  • Why does it happen?
    • Done in order to ensure all cells in the body have the same information.

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DNA REPLICATION

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DNA REPLICATION

  • STEPS IN DNA REPLICATION

1. Double helix is opened by the enzyme helicase.

      • Helicase breaks open the hydrogen bonds between bases.

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2. Free nucleotides are added to form base pairs according to Chargaff’s rules by an enzyme called DNA Polymerase.

Helicase

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DNA REPLICATION

3. DNA Polymerase causes the hydrogen bonds to form new rungs again and sugar-phosphate bonds form to create new side.

      • Resulting in two new identical DNA molecules.
        • each have:
          • one original side
          • one new side

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Semi- conservative