DNA

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DNA

• Deoxyribonucleic Acid

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The DNA Connection

• What have you learned about inheritance, DNA, and
  cell division up to this point?
• How do genes determine the traits of an organism?

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Where is DNA?

• Inside the nucleus of a cell.
• Chromosomes are made of DNA.
• Each chromosome contains thousands of genes.

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The Importance of DNA

• DNA tells the body how to make proteins.
• Proteins help to determine all of your physical
  traits.
• Directions for making proteins are found on
  genes.

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What are Chromosomes?

• Chromosomes are dark, rod-shaped bodies found in
  the cell nucleus.
• Chromosomes are composed mostly of proteins and
  DNA.

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History of DNA
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Rosalind Franklin

• Used X-ray diffraction (the way molecules bend
  X-rays) to determine the structure of molecules.
• One of the photographs suggested that DNA was a
  helical (spiral) structure.

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James Watson Francis Crick

• Created the double helix model.
• Recognized the ability of DNA to form exact
  copies of itself.

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Structure of DNA(Twisted Ladder Double Helix)

• Nitrogen
• Bases
• Sugars
• Phosphates

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The Sides of the Ladder

• Sugars and phosphates form the backbone of the
  DNA molecule.
• The name of the sugar is DEOXYRIBOSE.

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The Rungs of the Ladder

• The DNA molecule is made up of four different
  nitrogen bases.
• Adenine Thymine
• Cytosine Guanine
• The bases attach to the sugar part of the DNA
  backbone (sides).
• The order of the bases form a genetic code that
  specifies what type of protein will be produced.

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DNA Replication
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How Does it Work?

• DNA molecule unzips down the middle into two
  pieces.
• It breaks apart where the bases are joined.
• Extra bases are made in the cytoplasm.
• These bases pair up with the free bases.
• Two new complete DNA molecules form which are
  identical to the original DNA.

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