Mutations and Chromosomal Disorders

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Mutations and Chromosomal Disorders
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Mutation or birth defect?
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Mutations

• Random Accidents/Generally Insignificant or
  Beneficial or Bad
• Accidents- Replications/Transcriptions
• Mitosis
• Meiosis
• Gene Mutation More Common

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Do all mutations affect the organisms?

• No!
• Mutations may occur in a gene that is turned off
  in a cell (ex. Kidney cell vs. Heart Cell)
• When this occurs, there is no affect on the
  organism!
• Example Concert Sound Board

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Mutagen

• Factors in the environment that cause mutations
• Can you think of a few?
• X-Rays, UV waves, various chemicals

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Mutations

• Gene Mutations
• Substitution
• Deletion

• Chromosome Mutations
• Nondisjunction
• Fragmentation
• translocation
• Inversion
• Addition
• Deletion
• Polyploidy

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Translocation
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A mutation can only be passed on to
offspring IF

• THE MUTATION IS PRESENT IN THE GAMETES / SEX
  CELLS

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Gene Mutations

• Substitution-changes one codon
• Deletion (point mutation)-everything changes
  after the removal of that nucleotide

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Chromosomal Mutation

• Affects the whole chromosome and all genes on
  chromosomes
• Will be more detrimental!
• Mutations passed on if occur in sex cells

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Nondisjunction

• Chromosomes that normally separate during Meiosis
  stay together and can cause several genetic
  disorders in humans
• Examples Down Syndrome, Turners, Klinefelters

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• Downs Syndrome
• -extra copy of
• chromosome 21
• Turners Syndrome
• -underdeveloped sexual
• characteristics
• -webbed neck

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• Klinefelters Syndrome
• -two X chromosomes
• and a Y
• -male with underdeveloped sex organs

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Polyploidy

• Polygenetic Trait-
• Cells have some multiple of the normal chromosome
  number
• Example Plants with Polyploidy are usually
  larger with larger fruit

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Common Genetic Disorders
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Sex-linked Disorders

• Hemophilia
• Color-Blindness
• Male Pattern Baldness
• Duchenne Muscular Dystrophy

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Autosomal Disorders

• Sickle Cell- sickle shaped blood cells
• Tay Sachs-death by the age of 4
• Cannot breakdown lipids in the brain
• PKU-Caused by mutation and cannot break down
  phenylalanine
• Cystic Fibrosis-(refer to video on Active
  Transport) Missing gene to control formation of
  mucus
• Huntingtons Disease-fatal but do not appear
  until 30 years old-due to breakdown of the brain
  cells

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Detecting Genetic Disorders

• Karyotyping
• Amniocentesis
• Chorionic villus sampling
• Ultrasound

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Karyotype Normal
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Karyotype Edwards Syndrome
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Edwards Syndrome
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Amniocentesis (Ultrasound)
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Amniocentesis
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Amniocentesis
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Ultrasound
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Genetic Engineering
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Definition

• The process of producing altered DNA, usually by
  breaking a DNA molecule and inserting new genes

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Genetic Screening

• When a persons genetic make-up is analyzed to
  determine the possibility of genetic disorders
  for themselves and that could be passed on to
  future offspring
• Think of a couple who were choosing their embryo
  for invitro fertilization

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Recombinant DNA (Gene Splicing)

• DNA from two different species is joined together
• Provides a way of producing large amounts of
  sometimes rare substances
• Example Insulin and clotting factors that treat
  Hemophilia
• What is used to cut DNA? (Hint Electrophoresis)
• Restriction Enzymes

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Gene Therapy

• The process of correcting genetic defects by
  transferring normal genes to cells that have
  defective genes
• Sometimes normal genes are introduced to the cell
  be means of virus or bacteria
• Used in both Plants and Animals

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