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Mutations

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Germ-cell mutations occur in the organism's ... Non-disjunction: the failure of homologous chromosomes to separate from each ... Non-disjunction. Gene Mutations ... – PowerPoint PPT presentation

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Title: Mutations


1
Mutations
  • Chromosome Mutations and Gene Mutations
  • Chapter 12 Inheritance Patterns and Human
    Genetics

2
Mutations
  • Mutation a change in the nucleotide-base
    sequence of a gene or DNA molecule.

3
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.

4
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.

5
Lethal Mutations
  • Lethal Mutations cause death, often before birth.

6
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.

7
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.

8
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.

9
Inversion
10
Inversion
11
Deletion-the lost of a few bases or large regions
of a chromosome
12
Non-disjunction
13
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.

14
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.

15
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.

16
Frameshift Mutations
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19
Disorders- Gene Mutations
  • Sickle Cell Anemia- single base substitution
  • Cystic Fibrosis caused by the deletion of three
    nucleotides

20
The End
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