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Human Genetic Disorders

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How would this information help you determine whether the baby will have hemophilia? Human Genetic Disorders Genetic Disorder An abnormal condition that a person ... – PowerPoint PPT presentation

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Title: Human Genetic Disorders


1
Human Genetic Disorders
2
Genetic Disorder
  • An abnormal condition that a person inherits
    through genes or chromosomes.
  • Caused by mutations, or changes in a persons DNA
  • May occur during meiosis or may also have been
    already present in the parents cells

3
Cystic Fibrosis
Chromosome 7
CFTR gene
The most common allele that causes cystic
fibrosis is missing 3 DNA bases. As a result,
the amino acid phenylalanine is missing from the
CFTR protein.
Normal CFTR is a chloride ion channel in cell
membranes. Abnormal CFTR cannot be transported
to the cell membrane.
The cells in the persons airways are unable to
transport chloride ions. As a result, the airways
become clogged with a thick mucus.
4
Cystic Fibrosis Prognosis
  • Not sex-linked
  • No cure
  • Drugs to prevent infection
  • Physical therapy to break up mucus in lungs

5
Sickle-Cell Anemia
  • Genetic disorder that causes the production of
    abnormal hemoglobin.
  • Hemoglobin is a protein in RBCs that carriers
    oxygen.
  • Sickle-shape often blocks blood vessels resulting
    in lack of oxygen.

6
Genetics Behind Sickle-Cell
  • 9 of African Americans carry the sickle-cell
    allele
  • Sickle-cell allele is codominant with normal
    allele
  • Leads to resistance to malaria
  • 2 Sickle-cell alleles results in sickle-cell
    symptoms

7
Hemophilia
  • Genetic disorder in which a persons blood clots
    very slowly or not at all.
  • Individuals can bleed to death from a minor cut
    or scrape.
  • Caused by recessive allele on the X chromosome.
  • Treatment
  • Receive doses of missing clotting protein
  • Can lead relatively normal lives

8
Down Syndrome
  • Every cell has an extra copy of chromosome 21.
  • Result of error during meiosis
  • Distinctive physical appearance and some degree
    of mental retardation
  • Many lead full, active lives.

9
Tools in Diagnosing Genetic Disorders
  • Amniocentesis
  • Very long needle used to remove small amount of
    fluid that surrounds the baby
  • Fluid contains cells from the baby
  • Karyotype
  • Picture of all the chromosomes in a cell
  • Can reveal whether a developing baby has the
    correct number of chromosomes in its cells and
    whether it is a boy or girl.

10
Genetic Counseling
  • Helps couples understand their changes of having
    a child with a particular genetic disorder.
  • Uses karyotypes, pedigree charts, and Punnett
    squares to determine if parents are carriers,
    etc.

11
Summary Questions
  • Explain how genetic disorders occur in humans.
    Give two examples of genetic disorders.
  • Describe two tools that doctors use to detect
    genetic disorders.
  • How do the cells of people with Down syndrome
    differ from those of others? How might this
    difference arise?

12
Summary Questions
  • A couple with a family history of hemophilia is
    about to have a baby girl.
  • What information about the parents would you want
    to know?
  • How would this information help you determine
    whether the baby will have hemophilia?
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