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Human Heredity. 1) Autosomes –all the chromosomes except the sex chromosomes (in humans, there are 22 pair) 2) Sex chromosomes –The sex-determining chromosomes,

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Presentation on theme: "Human Heredity. 1) Autosomes –all the chromosomes except the sex chromosomes (in humans, there are 22 pair) 2) Sex chromosomes –The sex-determining chromosomes,"— Presentation transcript:

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

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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 HORMONESGenes inherited by both male and female but expressed only in one sex due to SEX HORMONES EX: Beards, breasts, antlers, milk production, feathers on birdEX: Beards, breasts, antlers, milk production, feathers on bird

9 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 mans index finger, the higher amt of prenatal testosterone (corresponds to physically aggressive behavior)

10 Examples Continued: Hairlip and Gout Dominant in males Recessive in females Spina Bifida: Dom. in females Rec. in Males

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

12 The Adams family

13 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 Red-Green Color Blindness (X R X r Y°) Hemophilia (inability of blood to clot) X H -normal X H Y° X h Y°-hemo Muscular Dystrophy (I muscles)

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16 4) Sex-linked traits –A recessive gene on the X chromosome –Examples: color-blindness & hemophilia –Genotypes:Phenotypes: – X N Ynormal male – X n Ycolorblind – X N X N normal female – X N X n carrier female – X n X n colorblind

17 normal vision weak red weak green

18 Phenotypes??? Cross of carrier female & normal male XNXN XnXn XNXN XNXNXNXN XNYXNY X N X n XnYXnY Y

19 X-linked recessive Most Common in males Bleeders Disease Missing clotting factor Bleeding spontaneously and in joints

20 Hemophila is sex-linked recessive trait. Normal clotting is dominant. Hemophiliac Male X Carrier (Heter.) Female LET: X H normal X h hemo X h hemo Y O no trait Y O no trait XhXh Y XHXH XhXh XHXhXHXh XHYXHY X h XhYXhY

21 XHXhXHXh X H X H X H X h X H Y X h Y Carrier Mom

22 Royal Hemophilia

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25 Sex linkage & calico cats

26 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

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31 Klinefelters syndrome

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34 Super male

35 Turners syndrome XX O 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.

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37 6) Pedigree6) Pedigree Chart showing family history of a trait 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)


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