Mutations

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Mutations

• Chromosome Mutations and Gene Mutations
• Chapter 12 Inheritance Patterns and Human
  Genetics

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Mutations

• Mutation a change in the nucleotide-base
  sequence of a gene or DNA molecule.

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Germ-cell Mutations

• Germ-cell mutations occur in the organisms
  gametes (egg or sperm)
• Germ-cell mutations do not affect the organism
  itself, but they can be passed on to offspring.

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Somatic-Cell Mutations

• Somatic-cell mutations take place in an
  organisms body cells and can therefore affect
  the organism.
• Somatic-cell mutations can not be inherited.

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Lethal Mutations

• Lethal Mutations cause death, often before birth.

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Mutations

• Some mutations result in phenotypes that are
  beneficial to the individual.
• Organisms with beneficial mutations have a better
  chance of surviving and reproducing.
• Mutations provide variation upon which natural
  selection acts.

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Mutations- Chromosomal or Single DNA nucleotide

• Chromosomal Mutations involve changes in the
  structure of a chromosome or the loss or gain of
  a chromosome.
• Gene Mutations involve a change in the
  nucleotide sequence either from substitution,
  deletion or insertion.

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Chromosomal Mutations

• Deletion a loss of a piece of chromosome due to
  breakage
• Inversion a chromosomal segment breaks off,
  flips around backward, and reattaches.
• Translocation a piece of one chromosome breaks
  off and reattaches to a non-homologous
  chromosome.
• Non-disjunction the failure of homologous
  chromosomes to separate from each other during
  the formation of gametes known as meiosis.

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Inversion
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Inversion
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Deletion-the lost of a few bases or large regions
of a chromosome
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Non-disjunction
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Gene Mutations

• Point Mutations the substitution, addition, or
  removal of a single nucleotide.
• - Substitution one nucleotide replaces
  another
• - Deletion one or more nucleotides are lost
  or deleted
• - Addition one or more nucleotides are
  added.

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Reading the DNA Molecule

• Reminder that the DNA molecule is read in groups
  of three consecutive nucleotide bases at a time.
• Each triplet or three consecutive nucleotide
  bases equal a codon.
• Codons code for amino acids or punctuation marks.

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Frameshift Mutations

• The loss or gain of a single nucleotide base
  within a DNA molecule will cause an incorrect
  grouping of the remaining codons, called a
  frameshift mutation.

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Frameshift Mutations
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Disorders- Gene Mutations

• Sickle Cell Anemia- single base substitution
• Cystic Fibrosis caused by the deletion of three
  nucleotides

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The End