Human Heredity

1. Human Heredity

2. 1) Autosomes all the chromosomes except the sex chromosomes (in humans, there are 22 pair) 2) Sex chromosomes The sex-determining chromosomes, the X & Y

3. 3) Karyotype Pictures of paired human chromosomes arranged by size, used to identify abnormalities in fetuses Cells from an amniotic fluid sample are cultured, stained & photographed

6. Who determines the Sex of offspring in Humans?

7. Sex-Limited, Influenced Traits and Sex Linked • Some traits are carried on the sex chromosomes = • X and Y • Most Traits are on X • Y is smaller, so few genes located.

8. Sex-Limited Traits • Genes inherited by both male and female but expressed only in one sex due to SEX HORMONES • EX: Beards, breasts, antlers, milk production, feathers on bird

9. Sex-Influenced Traits • Autosomal genes influenced by sex. • Genes DOMINATE in one sex and RECESSIVE in other • Males and females with the same genotype will have different phenoypes • EX: Index vs Ring finger Short index finger: Dom. in Males Rec. in Females (FYI: Shorter man’s index finger, the higher amt of prenatal testosterone (corresponds to physically aggressive behavior)

10. Sex-Influenced Traits • Examples Continued: • Hairlip and Gout Dominant in males Recessive in females • Spina Bifida: Dom. in females Rec. in Males

11. Sex-Influenced Traits • Other Examples: • Baldness: Dom. In Males Rec. in Females • B=baldness, B’=normal hair • BB=bald (male/female) • B’B’=normal hair (male/female) • BB’= bald (male) normal (female

12. The Adams family

13. Sex Linkage • Controlled by GENES on SEX CHROMOSOMES. • X chromosome is larger than y  more genes carried on the X • X-Linked Genes: genes found on X chromosome • Appear mostly in males • Only one copy of X; nothing to counteract “bad gene” • Females would need two copies to express trait

14. Traits on X Chromosome • Red-Green Color Blindness (XR Xr Y°) • Hemophilia (inability of blood to clot) • XH-normal XHY° XhY°-hemo • Muscular Dystrophy (I muscles)

16. 4) Sex-linked traits A recessive gene on the X chromosome Examples: color-blindness & hemophilia Genotypes: Phenotypes: XNY normal male XnY colorblind XNXN normal female XNXn carrier female XnXn colorblind

17. normal vision “weak red” “weak green”

18. Cross of carrier female & normal male Y XN XN XNXN XNY Xn XN Xn XnY Phenotypes???

19. Hemophilia • X-linked recessive • Most Common in males • “Bleeder’s Disease” Missing clotting factor Bleeding spontaneously and in joints

20. Hemophilia Hemophila is sex-linked recessive trait. Normal clotting is dominant. Hemophiliac Male X Carrier (Heter.) Female LET: XH normal Xh hemo YO no trait Xh Y XH XHY XHXh Xh Xh Xh XhY

21. Carrier Mom XHXh XHXH XHXh XHY XhY

22. Royal Hemophilia

25. Sex linkage & calico cats

26. Traits on Y CHROMOSOMES Ex. Long Hair on Earlobes 3 Muslim brothers from South India.

27. 5) Nondisjunction Failure of chromosomes to separate May cause a variety of birth defects, including trisomy 21 or Down syndrome

31. Klinefelter’s syndrome

34. Super male

35. Turner’s syndrome • Only 1 sex chromosome is present. • *Associated with underdeveloped ovaries, short stature, webbed neck, and broad chest. • *Individuals are sterile, and lack secondary sexual characteristics. • *Mental retardation typically not evident . XX XX O

37. 6) Pedigree Chart showing family history of a trait • Solid light = homozygous dominant, • solid dark = homozygous recessive, • half-circle = heterozygous

38. 7) Genetic disorders Harmful effects produced by mutated genes, most are recessive and few are lethal Example: sickle cell anemia

39. Normal, with malarial resistance Same as parents ; normal, no resistance; sickle-cell anemia

40. Polydactyly(multiple fingers and toes)