Mutation

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Mutation

• Changing your genes

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Mutation defined

• A Mutation occurs when a DNA gene is damaged or
  changed in such a way as to alter the genetic
  message carried by that gene.
• Example to right the enzyme that is catalyzing
  the production of flower color pigment has been
  altered in such a way it no longer catalyzes the
  production of the red pigment.

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Types of Mutation

• Gene mutation
• Chromosome mutation

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Gene Mutation

• Gene mutation
• most common
• within a gene
• one or more points changed
• Base(s) can be
• Substituted
• Deleted
• Added
• Result protein with 1 or more errors

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Gene Mutation an Analogy

• A sentence with three letter words, like the
  triplet codes in DNA.
• The fat cat ate the rat makes sense
• Gene mutation substitution
• Substitute an a for an o.
• The fat cot ate the rat nonsense, but only one
  word affected
• Result Protein may still be able to function

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Gene Mutation an Analogy continued

• The fat cat ate the rat makes sense
• Gene mutation deletion
• Remove the first a.
• The ftc ata tet her at nonsense, and many
  words affected.
• Result Protein most likely will not function
• How would an addition/insertion affect the
  resulting amino acids?

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Chromosomal Mutations

• Change in structure of an entire chromosome
• or
• Change in chromosome number

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Chromosomal Mutations continued

• Changes in chromosomal structure
• A chromosome can become tangled during cell
  division thus rearranging the segments
• Five possibilities can happen
• Translocation
• Inversion
• Deletion
• Duplication
• Addition

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Chromosomal structure

• Translocation
• Segment of one chromosome is transferred to
  another

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Chromosomal structure

• Inversion
• Segment is rotated so the order of the genes is
  reversed

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Chromosomal structure

• Deletion
• A segment breaks off so genes are lost

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Chromosomal structure

• Duplication
• A batch of genes are duplicated so now have
  double of these genes

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Chromosomal structure

• Addition
• Repetition of genes on a homologue

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Chromosomal Mutations continued

• Change in chromosome number
• Two types
• Polyploidy
• Nondisjunction

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Chromosome number

• Polyploidy
• Mostly in plants
• Multiples of n
• (3n, 4n, 5n)
• Improper separation during meiosis
• Often yields larger fruit

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Chromosome number

• Nondisjunction
• Misplacement of a whole chromosome during meiosis
• Results
• Trisomy or 2n 1
• ex Downs Syndrome
• Monosomy or 2n -1
• ex Turners Syndrome