DNA

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DNA

• The Master Molecule of Life

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THE DNA MOLECULE

• DNA-Deoxyribonucleic acid- stores and passes on
  genetic information from one generation to the
  next
• Many scientists believe that the discovery of the
  structure of DNA was the most important
  biological breakthrough of the 20th century
• James Watson, Francis Crick, and Maurice Wilkins
  are three of the scientists credited with the
  discovery of the structure of the DNA molecule.
• They discovered that chromosomes are made up of
  long strands of DNA molecules. It is the DNA
  molecules in chromosomes that make up genes.
• A gene is the basic unit of heredity that
  consists of a segment of DNA on a chromosome

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The Structure of DNA

• The DNA molecule looks like a twisted ladder, or
  spiral staircase
• The sides of the ladder are made up of molecules
  of the sugar deoxyribose and phosphate groups.
  The rungs of the ladder are formed by pairs of
  substances called nitrogen bases
• The sugars are chemicals on the outside of the
  double helix that hold the bases together
• Phosphates are the chemicals that join the sugars
  together
• There are 4 nitrogen bases in DNA
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)

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THE Structure of DNA (cont)

• The order of these substances on the DNA molecule
  determines what type of gene it is.
• Adenine always pairs with Thymine
• Cytosine always pairs with Guanine
• The order of the nitrogen bases on a DNA molecule
  determines the particular genes on a chromosome
• The genetic code is actually the order of
  nitrogen bases on the DNA molecule (ACGGTTCAAG)
  for example

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A Diagram of the DNA molecule
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Bye Bye!!
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Elements

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