Karyotypes and Mutations

1. Karyotypes and Mutations

2. Karyotype • An orderly display of magnified images of the individual’s chromosomes • Shows the chromosomes as they appear in metaphase.

3. What is a Normal Karyotype? • We are supposed to have 46 total chromosomes in each cell (22 pairs of autosomes = 44, + 2 sex chromosomes).

4. One source:Amniocentesis • Take fluid from amniotic fluid around the baby • Can make a karyotype to see if there is a genetic disorder

5. Preparing a Karyotype • 1. Use blood cells.

6. Essay: Preparing a Karyotype • 2. Burst RBC (red blood cells) in hypotonic solution. • Release WBC (white blood cells).

7. Essay: Preparing a Karyotype 3. Use a centrifuge to separate the white blood cells from the rest of the blood fluid

8. Preparing a Karyotype • 4.Add chemical (colchicine) to stop the chromatids in metaphase (stops spindle fibers from forming)

9. Preparing a Karyotype (cont) • 5. Drop on a slide.

10. Preparing a Karyotype (cont) • 5. Take a picture • 6.Sort by size and shape from largest to smallest

11. Other types of Karyotypes

12. Types of Karyotypes • Fluorescent to detect a marker showing certain defect

13. Types of Karyotypes • Colored dyes for certain chromosomes

14. Types of Karyotypes • Ideogram: bands locate sites on chromosome

15. Normal Karyotype • WHY? • Is it a Male or a female?

16. Down Syndrome Karyotype • Trisomy 21

17. Down Syndrome • Trisomy 21 • Folds over eyes • Sluggish muscles • Mental Problems

18. Down Syndrome • The most common chromosome number abnormality • Round face • flattened nose bridge • small, irregular teeth

19. Down Syndrome • Short Stature • heart defects • susceptibility to respiratory infection , leukemia and Alzheimer’s

20. As the age of the mother increases above 30, the frequency of Trisomy 21 also increases Does the mother’s age matter?

21. Nondisjunction • Uneven distribution of chromosomes in cell division

22. 47 XXY syndrome male testes small (sterile) breast enlargement feminine body contours Klinefelter’s Abnormal Sex Chromosomes

23. Klinefelter’s Syndrome • also XXYY, XXXY, XXXXY

24. TURNER SYNDROME • XO (only one X) • short • often web of skin between neck and shoulders • sterile • poor breast development

25. Turner Karyotype

28. What about… • MUTATIONS?

30. DELETION Fragment of the chromosome is lost

31. Duplication Fragment of one chromosome attaches to a homologous chromosome

32. Translocation Fragment reattaches in reverse direction (less likely to produce harm)

33. INVERSION • The chromosome breaksin two places, a piece of the chromosome is removed and the chromosome pieces remaining rejoin.

34. Inversions • Inversions, by definition, do not involve loss or gain of chromosomal material.

35. INVERSION 46,XY,inv(16) • The left one is normal and the right one is inverted near the centromere.

36. 45,XX,rob(13,14) A Robertsonian translocation (an end to end fusion of #13 and #14) There is no net gain or loss of genetic material in this person so they would have a normal phenotype.

37. Chromosomes from the father of a retarded child... a portion of chromosome 11 (blue) has been transfered to chromosome 1(yellow). Applications

38. Ideogram Show only one set of chromosomes