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Gene

Gene. A unit of heredity that controls the development of one trait Made of DNA. Allele. Member of a paired gene One allele comes from each parent Dominant alleles are expressed Recessive alleles are not expressed in the presence of a dominant allele

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Gene

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  1. Gene • A unit of heredity that controls the development of one trait • Made of DNA

  2. Allele • Member of a paired gene • One allele comes from each parent • Dominant alleles are expressed • Recessive alleles are not expressed in the presence of a dominant allele • Recessive alleles are only expressed if both recessive alleles are present

  3. Examples of Alleles Dwarfism = D Normal height = d DD = Dwarfism Dd = Dwarfism dd = Normal height Dwarf Band

  4. Genotype • Genetic make up • Represented by alleles • DD & Dd are genotypes for dwarfism

  5. Phenotype • A trait • Genotype determines the phenotype • Dwarfism is a phenotype

  6. Codominant • Two different alleles are both dominant • A = allele for type A blood • B = allele for type B blood • AB = results in type AB blood

  7. Karyotype • Picture of chromosomes from an individual

  8. Homologous Chromosomes • Chromosomes of the same pair • Karyotypes are usually arranged with homologous chromosomes paired together

  9. Mutation • Change in a gene or chromosome • Causes an abnormal trait

  10. Mutagen • Agent that causes mutations • Cigarette smoke • Pesticides • X-rays • Ulatraviolet light • Nuclear radiation

  11. Sex Chromosomes • Male have Xy • Male gametes have either X or y • Females have XX • Female gametes have X

  12. Autosomes Chromosomes 1-22

  13. X-Linked (vs Y- linked)Traits • Why are there more X-linked that Y- linked disorders? • Who suffers more frequently from sex-linked disorders? Why?

  14. Which karyotype is which?A B

  15. Trisomy 21: Down Syndrome • Large tongue • Flat face • Slanted eyes • Single crease across palm • Mental retardation • Some are not

  16. Maternal Age & Down Syndrome

  17. Trisomy 18: Edward Syndrome • Heart defects • Displaced liver • Low-set ears • Abnormal hands • Severe retardation • 98% abort • Lifespan < 1 year

  18. Trisomy 13: Patau Syndrome • Cleft lip and palate • Extra fingers & toes • polydactylism • Defects • Heart • Brain • Kidneys • Most abort • Live span < 1 month

  19. Klinefelter Syndrome • Breast development • Small testes • Sterile • Low intelligence • Not retarded Klinefelter Website

  20. Turner Syndrome • Short • Not go through puberty • Produce little estrogen • Sterile • Extra skin on neck

  21. Fetal Testing

  22. A man & woman are both carriers (heterozygous) for albinism. What is the chance their children will inherit albinism?

  23. AA = Normal pigmentation Aa = Normal pigmentation (carrier) aa = Abino A A a a Man = Aa Woman = Aa

  24. A A a a Aa AA Aa aa

  25. Aa AA Aa aa Genotypes 1 AA, 2Aa, 1aa Phenotypes 3 Normal 1 Albino Probability 25% for albinism

  26. A man & woman are both carriers (heterozygous) for PKU disease. What is the chance their children will inherit PKU disease?

  27. PP = Normal Pp = Normal (carrier) pp = PKU disease Pp PP Pp pp P p P p

  28. Pp PP Pp pp Genotypes 1 PP, 2Pp, 1pp Phenotypes 3 Normal 1 PKU disease Probability 25% for PKU disease

  29. A man with sickle cell anemia marries a woman who is a carrier. What is the chance their children will inherit sickle cell anemia?

  30. SS = Normal Ss = Normal (carrier) ss = Sickle Cell ss Ss Ss ss S s s s

  31. ss Ss Ss ss Genotypes 2 Ss, 2ss Phenotypes 2 Normal (carriers) 2 Sickle cell Probability 50% for Sickle cell

  32. A man with heterozygous dwarfism marries a woman who has normal height. What is the chance their children will inherit dwarfism? Dwarfism is dominant.

  33. DD = Dwarf Dd = Dwarf dd = Normal Dd Dd dd dd d d D d

  34. Dd Dd dd dd Genotypes 2 Dd, 2dd Phenotypes 2 Normal 2 Dwarfs Probability 50% for Dwarfism

  35. XH XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Normal Male Xhy = Hemophiliac Male

  36. A man with hemophilia marries a normal woman who is not a carrier. What is the chance their children will inherit hemophilia? Hemophilia is X-linked recessive.

  37. Xh XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Normal Male Xhy = Hemophiliac Male XH XH Xh XH Xh XH Xh XHy XHy y

  38. XH XH Xh XH Xh XH Xh XHy XHy y Genotypes 2 XH Xh, 2XHy Phenotypes 2 Carrier Females 2 Normal Males Probability O% for Hemophilia

  39. A normal man marries a normal woman who is a carrier for hemophilia. What is the chance their children will inherit hemophilia?

  40. Xh XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Normal Male Xhy = Hemophiliac Male XH XH XH Xh XHy Xhy XH Xh XH y

  41. XH Xh Genotypes XH XH , XH Xh, XHy, Xhy XH XH XH XH Xh Phenotypes 2 Normal Females 1 Normal Males 1 Male Hemophiliac XHy Xhy y Probability 50% for Male Hemophilic 0% for Female Hemophilic

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