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GT Biology

GT Biology. March 8, 2011. Karyotypes. A B C D E F G. A B C D E F G X Y Z. A B C D E F G. A B E D C F G. A B C D E F G. A B C B D E F G. Warm-up. What type of mutations are the following? What is a karyotype?. A. B. C. Objective.

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GT Biology

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  1. GT Biology • March 8, 2011 Karyotypes

  2. A B C D E F G A B C D E F G X Y Z A B C D E F G A B E D C F G A B C D E F G A B C B D E F G Warm-up • What type of mutations are the following? • What is a karyotype? A B C

  3. Objective • SWBAT explain karyotypes and how they relate to mutations

  4. Homework • Read pgs 228-232 • Answer questions 3-6

  5. Today • What are karyotypes? • What do they tell us? • How do they relate to genetic disorders?

  6. What do these have in common? • What do you think they show? • Are they the same for all organisms?

  7. What is a karyotype • Karyotyping examines the chromosomes of a person • An image of chromosomes • Images are taken during metaphase • Homologs are paired and arranged by size and shape

  8. How to obtain a karyotype • There are two methods to obtain a karyotype: • A cell in mitosis is photographed • Amniocentesis: amniotic fluid and cells from the fetus are withdrawn to be tested for a disease • These are still in mitosis

  9. How can karyotypes be used? • To study chromosomes and chromosomal abnormalities • To better explain genetic disorders

  10. Genetic Disorders • What do you think a genetic disorder is? • Can you tell if someone has sickle cell anemia from a karyotype?

  11. Genetic Disorders • Definition: an illness that is caused by an abnormality that occurs within a gene or chromosome

  12. Polyploidy • It is possible for some cells and organisms to have more than one set of pair homologs • Happens during mitosis or meiosis • Results in cells that are 3n, 4n, 5n or more • This most often occurs in plants but can occur in animals • Plants and fruits grow bigger than normal • These animals are often sterile • How could this be beneficial to farmers?

  13. Types of Genetic Disorders • Nondisjunction: the addition or deletion of a whole chromosome • During anaphase I chromosomes do NOT separate • The cell with an additional chromosome is called trisomy once fertilization occurs • The cell with a deletion of a chromosome is called monosomy once fertilization occurs

  14. Trisomy 21: Down’s Syndrome • Caused by nondisjunction • Symptoms of Down’s Syndrome: • Small skull • Abnormally round head • Slanting eyes • Short hands • Small mouth and enlarged tongue • Low muscle tone

  15. Another Example of Trisomy • Trisomy: Kleinfelter’s Syndrome (a male who has feminine features) • Symptoms of Kleinfelter’s Syndrome • Male infertility • Small testicles • Round body type • Difficulty reading, writing and language problems

  16. Example of Monosomy • Monosomy: Turner’s Syndrome (a female who has prepubescent features) • Symptoms of Turner Syndrome • Short stature • Low hairline • No menstruation • Small finger nails • Shield Shaped Thorax • Folds of skin on the neck

  17. Cri-du-chat Syndrome • The loss of part of chromosome 5 • Symptoms: stomach, intestinal and heart problems and mental retardation

  18. Use of Karyotypes • After learning about these types of genetic disorders, how do you think karyotypes could be of used?

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