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Karyotypes and Mutations

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Presentation on theme: "Karyotypes and Mutations"— Presentation transcript:

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

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

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