Nucleic Acids The Genetic Material

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Nucleic AcidsThe Genetic Material
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Two types of Nucleic acids

• RNA
• DNA

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• Stores hereditary information
• Made of monomers called nucleotides

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• DNA ? Polymer Nucleotide ? Monomer
• Each Nucleotide has 3 parts
• 1) 5 carbon sugar ? Deoxyribose
• 2) Phosphate group ? PO4
• 3) Nitrogen Base

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Identifying the Genetic Material

• Experiments of Griffith and Avery yielded results
  that suggested DNA was genetic material (1944)

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• Hershey Chase used the bacteriophage T2 and
  radioactive labels to show that virus genes are
  made of DNA, not protein (1952)

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• DNA stores information that tells cells which
  proteins to make and when to make them

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The Structure of DNA

• Discovered by Watson Crick in 1953 received
  Nobel Prize in 1962 along with Maurice Wilkins

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• DNA ? Polymer Nucleotide ? Monomer
• Each Nucleotide has 3 parts
• 1) 5 carbon sugar ? Deoxyribose
• 2) Phosphate group ? PO4
• 3) Nitrogen Base

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A T G C
Human 30 30 19 19
Plant 27 27 22 22
Virus 21 22 28 27

• DNA forms a spiral ladder ? Double Helix
• Double helix is held together by weak Hydrogen
  bonds
• Erwin Chargaff Discovery? Chargaffs Rule? AT,
  GC

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DNA Replication

• Phase of Cell Cycle? Why replicate?
• Step 1 DNA Helicase unzips DNA by breaking weak
  Hydrogen bonds.
• Step 2 DNA polymerase adds nucleotides to
  exposed nitrogen bases.
• Step 3 Two DNA molecules form that are
  identical to original.

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• DNA is referred to as Semi-conservative, Each
  DNA molecule ? 1 template 1 new strand
• DNA polymerase proofreads DNA during its
  replication so that very few errors occur