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Human Genetics

Human Genetics. Human Genetic Map. http://www.hulu.com/watch/91438/ngc-presents-genetic-roadmaps. How many chromosomes are in a human sperm or egg?. 23. How many chromosomes does a human have?. 23 pairs. What is the total human chromosome number?. 46.

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Human Genetics

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  1. Human Genetics

  2. Human Genetic Map • http://www.hulu.com/watch/91438/ngc-presents-genetic-roadmaps

  3. How many chromosomes are in a human sperm or egg? • 23

  4. How many chromosomes does a human have? • 23 pairs

  5. What is the total human chromosome number? • 46

  6. Do all animals have 23 chromosome pairs? • No, different species have different chromosome numbers and the number is not correlated to the complexity of the animal

  7. How can you tell if a human child has the correct number of chromosomes? • Amniocentesis– removal amniotic fluid to check chromosomal abnormalities • Chorionic villus Sampling • Diagnosis chromosome abnormalities • Fetal Blood sampling • Check for genetic or chromosomal abnormalities

  8. Determination of sex What are sex chromosomes? • 23 pair of chromosomes (X and Y) How many sex chromosomes are there? • 2 –X chromosome and Y chromosome How is your sex detemined? • Female has 2 X chromosomes • Male has 1 X and 1 Y chromosome

  9. Determination of sex • How can you predict the expected sex of a child? • By using a punnett square • A female can donate only an X chromosome • A male can donate either a X or a Y chromosome • What is the chance that the offspring will be male or female? • 50 %

  10. Other Facts about Chromosomes • Autosomes • Other 44 body chromosomes • Sex Chromosomes • 45 & 46 chromosomes • Karyotype • A picture of chromosomes

  11. Pedigree • Pedigree Chart • Chart that shows the relationship within a family • Used to study human inheritance patterns

  12. Royal Family Pedigree

  13. How do you read Pedigree Chart? • Who is the carrier for color-blindness? • Which parent is unaffected? • Which grandchild was the first to exhibit colorblindness and hemophilia? • How many children affected?

  14. Royal Family Pedigree

  15. Human Genetic Disorders

  16. Genetic Disorders • Gene mutations • inherited from a parent or acquired. • A hereditarymutation is a mistake that is present in the DNA of virtually all body cells. • Hereditary mutations (germ line mutations) • the gene change exists in the reproductive cells and can be passed from generation to generation, from parent to newborn.

  17. Autosomal Disorders • Disorders involving the other 22 pairs of chromosomes. • Can result from an extra chromosome or defective genes

  18. Autosomal Disorders • Recessive Alleles Disorders • Albinism • Cystic fibrosis • Galactosemia • Tay-Sachs Disease • Dominant Alleles Disorders • Achondroplasia • Huntington’s disease • Codominant Alleles Disorders • Sickle cell disease

  19. Recessive Autosomnal Disorders Cystic Fibrosis • A recessive disorder that occurs in about 1 of 2,500 people of white European ancestry. • Mutation gene on chromosome 17. • Characterized by excessive secretion of the mucus in the body.

  20. Recessive Autosomnal Disorders Albinism • Patients are unable to produce skin or eye pigments, and thus are light-sensitive

  21. Recessive Autosomnal Disorders Tay-Sachs Disease • Central nervous system degrades, ultimately causing death. • Buildup of fatty deposit in brain & mental disability • Found in Chromosome 15 • Common among people of Jewish, eastern Europe descent.

  22. Recessive Autosomnal Disorders Galactosemia • 1 in 50000-70000 affected • Absent of gene that codes for enzyme that break down galactose • Mental disabilities, enlarged liver, and kidney failure. • Monitor galactose intake

  23. Autosomal Disorders • Dominant Alleles Disorders • Achondroplasia • Huntington’s disease

  24. Dominant Autosomal Disorders Huntington Disease • A dominant disorder that occurs in about 1 of 10,000 people. • Chromosome 4 is responsible. • Causes degeneration of neurons producing dementia, and random jerking movements

  25. Dominant Autosomal Disorders Achondroplasia (Dwarfism) Mini-Me • Has small body size and limbs that is short • No treatment

  26. Autosomal Disorders • Codominant Alleles Disorders • Sickle cell disease

  27. Codominant Autosomnal Disorders Sickle-Cell Anemia • Occurs in about people with African descent • The defective gene on chromosome 11 • Blood cell sickled on increase resistance Malaria

  28. Sex Linkage (X-Linked) Disorders If chromosomes are paired with other chromosomes with the same genes, what happens when you pair an X and Y chromosome? • Females have two forms of the same gene, just like on the rest of the chromosomes, • Men have only the form of the gene found on the X chromosome

  29. If color blindness is a trait inherited on the X chromosome, why are men more likely to be color blind? • The man doesn’t have a second X chromosome to keep recessive genes from being expressed

  30. Sex-linked Disorders • Colorblindness • Hemophilia

  31. Sex-Linked Disorders Hemophilia –Royal Family Disease • Recessive disorders that affect 1 of 5,000 males. • Interfere with normal blood clotting and occur at different loci on the X chromosome.

  32. Sex-Linked Disorders Color Blindness • Genetic X-linked recessive disorder. • Occurs in 1 of 10 males

  33. Informal colorblind test

  34. FIND A CIRCLE, SQUARE, and/or STAR

  35. FIND CAR, BOAT, DOG, or BALLOON

  36. Color BlindnessTest Color Blindness

  37. Chromosomal Autosomal Disorders • Down Syndrome • Extra copy of chromosome at 21 • Sex Chromosome Disorders • Turner’s Syndrome • Only One X chromosome (XO) • Klinefelter’s Syndrome • Extra X chromosome (XXY)

  38. Chromosomal Autosomal Disorders Down Syndrome • Occurs in about 1 in 1,000 live births. • An extra chromosome is attached to the 21st pair. • Risk increases with pregnancies of women over age 35

  39. Chromosomal Sex-Linked Disorders KlinefelterSyndrome(XXY, XXXY, XXXXY) • Occurs in about 1 of 1,000 males. • Caused by an extra X chromosome • Some development of breast tissue, little body hair, small testes, infertility, and evidence of mental retardation may or may not be present.

  40. Chromosomal Sex-linked Disorders Turner’s Syndrome (XO) • Occurs in about 1 of 10,000 females. • One of the X chromosomes is either missing or inactive. • Women have immature female appearance, do not develop secondary sex characteristics, and lack internal reproductive organs.

  41. Hermaphrodite • An individual whose body contains tissue of both male and female gonads. • The ovaries and testes may be present as separate organs, or ovarian and testicular tissue may be combined in the same organ. • Causes • Adrenal Gland imbalance during pregnancy • Male hormone imbalance

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