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

21. Nondisjunction
Uneven distribution of chromosomes in cell division

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

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 breaks in 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.
45,XX,rob(13,14) A Robertsonian translocation

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

38. Ideogram
Show only one set of chromosomes