Karyotypes and Pedigrees

1. Karyotypes and Pedigrees Genetics and Chromosomal Analysis

2. Chromosomal Analysis • There are various ways to analyze chromosomes: • 1. Karyotypes • 2. Chromosome painting • 3. Gel electrophoresis (DNA fingerprinting)

3. Chromosome painting: using fluorescents to compare chromosomes

4. Gel Electrophoresis: separating DNA according to their molecular size

5. Karyotype- a chart of chromosomes pairs

6. Male Karyotype

8. Any individual with at least one Y chromosome is male and without one Y is female. • XX- Female • XY –Male

9. Down Syndrome (trisomy-21) • Autosomal nondisjunction • affected individuals survive to adulthood • It occurs in about 1 and 700 live births

10. - There is a third chromosome on the 21st pair. - They have varying degrees of mental disability. - The incidence is higher among older mothers, especially those over 40.

12. Characteristics: short, slanted eyes, thick tongue

13. SEX CHROMOSOME NONDISJUNCTION –Unusual numbers of sex chromosomes

14. Turner’s Syndrome • XO • One X chromosome is missing • FEMALES ONLY! • Monosomy X – gets only • ONE X chromosome • Sterile female • Low intelligence • No breasts (no secondary sex characteristics)

16. Klinefelter syndrome • XXY • Extra X chromosome • MALES ONLY! • causes a male to be sterile • No beard, no deep voice, no masculine muscle tone (no secondary sex characteristics)

17. Most of these individuals lead normal lives, but they can not have children and some may have some degree of mental retardation.

19. Superman SyndromeXYY • Male • Has an extra Y chromosome • On average 3” taller than your average male • Clinical phenotype of this syndrome is normal

21. RECESSIVE AUTOSOMAL DISORDERS-Deals with chromosome pairs #1-22

22. Cystic Fibrosis • Excess mucus in lungs • Mostly found in Caucasian population • Chromosome #7

23. Phenylketonuria (PKU) • Lack of normal skin pigmentation • Mental retardation • Can prevent with special diet • Chromosome #12 • Absence of certain enzyme • Damage to Central Nervous System

25. Tay-Sachs Disease • Lipids (fats) in brain cells • Affects Central Nervous System • Mental deficiency • Fatal, usually causes death by age 2 • Mostly in Jewish population • Chromosome #15

26. DOMINANT AUTOSOMAL DISORDERS - Deals with chromosome pairs #1-22

27. Huntington’s Disease • Chromosome #4 • Memory loss • Uncontrolled movements • Onset occurs between the ages of 30-50 (middle age) • Forgets things, stumbles • Cause: abnormal repeating of certain bases

28. CODOMINANT AUTOSOMAL DISORDERS

29. Sickle Cell Anemia • Sickle-shaped red blood cells • Difficulty breathing • Nitrogen base is changed, affects HEMOGLOBIN that carries oxygen • Mostly in African Americans • Cells clot • Capillaries are cut causing bleeding internally. • Chromosome #11

30. Pedigree- a graphic representation of genetic inheritance from generation to generation

31. Pedigree Symbols Normal female Affected female Carrier/heterozygous female Normal male Affected male Carrier/heterozygous male Death Married Parent and Offspring

32. A carrier is represented by a half shaded circle or square. They are heterozygous- they have a recessive gene but it does not show.

34. DNA FINGERPRINTING aka GEL ELECTROPHORESIS

35. Why ?? To determine whether suspects have been at a crime scene/location • Who?? Law enforcement

36. Small DNA samples can be obtained from blood, hair, skin, and copied millions of times. • How does it work??? The DNA is cut into fragments of different lengths DNA fragments can then be separated by electrophoresis, and compared with those obtained from a crime scene

38. The genes follow standard patterns from person to person • BUT the non-coding segments produce distinct combinations of patterns that are unique to each individual • SO unique fingerprints can be used to identify a single person.

39. No two people have the same DNA (except identical twins)