Chromosomes and Inheritance Chapter 12 (231-241)

1. Chromosomes and InheritanceChapter 12 (231-241)

2. Telomeres p arm q arm Telomeres Parts of Chromosomes • Telomeres • Centromeres • Locus

3. Picture of chromosomes • Homologous chromosomes contain the same genes • Often arranged with autosomes (found in both sexes) in descending order and sex chromosomes separate Karyotype

4. X-Linked Inheritance Color blindness(X-linked recessive) Hemophilia (X-linked recessive)

5. Autosomal Recessive Disorders Sickle-Cell Anemia Red blood cells take on a curved shape Clot in the capillaries Decreased oxygen supply to brain & muscles Werner Syndrome Premature aging Begins during adolescence Mapped to chromosome 8

6. Autosomal Dominant Disorders Polydactyly Extra fingers or toes Achondroplasia Growth related defect Cartilage growth in the long bones is slow Results in short stature

7. Retinitis Pigmentosa X-linked recessive, Autosomal dominant or Autosomal recessive Eye diseases that affect the retina Degeneration of cones and rods in the eye Loss peripheral vision

8. Pedigree Analysis Diagrams of family history Used to determine if a disease or condition is dominant, recessive, or X-linked Use symbols to represent individuals

11. Polyploidy The addition of one or more sets of chromosomes to a genome Malfunction in meiosis Egg or sperm end up with two sets of chromosomes Detrimental in humans Preferred in some plant species

12. Aneuploidy One chromosome too many or missing one chromosome Common in humans Common in miscarriages Ex. Down syndrome Result of nondisjunction

13. Nondisjunction

15. Most result in a miscarriage, except for those that occur on chromosome 13, 18, or 21

16. Trisomy Zygote ends up with 3 chromosomes instead of 2 for a given pair of chromosome.

17. Down Syndrome (Trisomy 21) • 1 in 800-1,000 births • Large tongue • Flat face • Single crease across palm • Slanted eyes • Mental retardation -Some are not • Increased risk for congenital hear defects and leukemia

18. Edward Syndrome (Trisomy 18) • 1 in 3,000 births • Affects more girls than boys • Heart defects • Displaced liver • Clenched hands • Low-set ears • Severe retardation • 98% abort • Lifespan < 1 year

19. Patau Syndrome (Trisomy 13) • 1 in 10,000 births • Cleft lip and palate • Small eyes • Extra fingers & toes • polydactylism • Defects • Heart • Brain • Kidney • Most abort • Live span < 1 month

20. Klinefelter Syndrome • 1 in 500-1,000 births • Breast development • Small testes • Sterile • Autoimmune disorders • Low intelligence • Not retarded

21. Turner Syndrome • 1 in 2,500 births • Short • Not go through puberty • Webbed neck • Dropping eyelids • Produce little estrogen • Sterile • Increased risk for obesity, cataracts, arthritis, scoliosis

22. Aberrations within chromosomes Deletions: Ex. Cri-du-chat syndrome Inversions: Ex. Acute Myeloid Leukemia Translocations: Duplications:

23. Deletion • Part of a chromosome is deleted

24. Cat Cry Syndrome • Deletion on chromosome 5 Prader-Willi Syndrome • Deletion on chromosome 15

25. Part of a chromosome is inverted A B C D A E B C F D I E H G F G J H I J Inversion

26. Inversion of Chromosome 16 • Inversion between chromosome 13 and 22 • Acute myeloid leukemia

27. Translocation • Part of a chromosome attaches to a nonhomologous chromosome

28. Translocation of Between Chromosomes 1 and 3 • Part of chromosome 3 attached to chromosome 1 • Acute myeloid leukemia

29. Part of a chromosome is duplicated Duplication

30. Chromosome 10q duplication syndrome • Mental retardation • Defects in many organs • Heart • Kidneys • Bones • Muscles • Life span less than 1 year