DNA: The Molecule of Heredity

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DNA The Molecule of Heredity

• What is DNA?
• What is Replication of DNA?

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• So, what's the difference between DNA and a
  chromosome?
•      A chromosome is made up of DNA and the
  proteins attached to it. 
• All of the DNA in a cell is found in individual
  pieces, called chromosomes. 

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• The basic structure of the DNA molecule is
  helical, with the bases being stacked on top of
  each other

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DNA is made up of subunits which scientists
called nucleotides.

• Each nucleotide is made up of a sugar, a
  phosphate and a base.
• There are 4 different bases in a DNA molecule
• adenine (a purine)
• cytosine (a pyrimidine)
• guanine (a purine)
• thymine (a pyrimidine)

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• The number of adenine bases equals the number of
  thymine bases
• The number of guanine bases equals the number of
  cytosine bases

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What pairs up?

• A -- T
• C -- G

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Usefulness of DNA

• DNA is the fundamental building block for an
  individuals entire genetic makeup.
• It is a component of virtually every cell in the
  human body, and a persons DNA is the same in
  every cell.
• That is, the DNA in a persons
• blood is the same as the
• DNA in his skin cells, saliva,
• and other biological material.

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• DNA analysis is a powerful tool because each
  persons DNA is unique (with the exception of
  identical twins).
• DNA evidence collected from a crime scene can
  implicate or eliminate a suspect, similar to the
  use of fingerprints. It also can analyze
  unidentified remains through comparisons with DNA
  from relatives..

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• DNA is also a powerful tool because when
  biological evidence from crime scenes is
  collected and stored properly, forensically
  valuable DNA can be found on evidence that may be
  decades old. Therefore, old cases that were
  previously thought unsolvable may contain
• valuable DNA evidence
• capable of identifying the perpetrator.
• Similar to Fingerprints

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