Warm-up

1. March 14 & 15, 2006 Warm-up Describe the following aspects of the genetic disorder you have researched: • What is your disorder? • Is it Dominant or Recessive? • Is it Autosomal or X-linked? When you are done, put your warm-up and your brochure in your folder, and turn it in. Then, pick up the handouts at the front of the classroom.

2. Beyond Mendel… Mutations, Gene Linkage, Gene-Mapping, Polygenic Traits, Non-disjunctiondisorders, Prenatal Diagnosis

3. Mutations • Definition • Mutations in Genes • Point Mutations • Frame-shift Mutations • Mutations in Chromosomes • Deletion • Duplication • Inversion • Translocation Back to “Beyond Mendel”

4. Mutations • Definition: A change in the genetic material of a cell • Somatic: Affects body cells; can’t be passed on to next generation • Germ-line: Affect gametes; can be passed on to next generation Back to Mutations

5. Mutations in Genes • Point Mutation: Affects one nucleotide(One nucleotide is replaced by another) • Types of point mutations • Silent mutations: Codes for same amino acid • Missense mutations: Code for a different A.A. • Nonsense mutations: Code for a stop codon • Example: Sickle-cell Anemia

6. Mutations in Genes • Frameshift Mutation: An insertion or deletion that shifts the reading frame • Example of Insertion: TA • Example of Deletion: CGCATGGAATACC H THE TEF FAT ATC CAT ATA TET ATE THE HER RAT AT Back to Mutations T

7. 1. Deletion: A segment of the chromosome is removed 2. Duplication: A segment of the chromosome is repeated A B C D E F G H A B C E F G H E D E F A B C D F G H A B C B C G H 3. Inversion: A segment within a chromosome is reversed 4. Translocation: A segment from one chromosome moves to another, non-homologous one A B C D E F G H A D C B E F G H Back to Mutations M N O A B C D E F G H C D E F G H M N O P Q R A B P Q R

8. Linked Genes In flies, grey bodies (G) and normal-wing size (W) are dominant to black bodies (g) and small wing size (w). Predict a cross between GgWw and ggww.

9. Predicted Cross GW Gw gW gw gw gw gw gw 25% GgWw 25% Ggww 25% ggWw 25% ggww

10. Actual Results 8.5% 8.5% 41.5% 41.5% 41.5% 41.5%

11. Linked Genes The genes for body color and wing size are linked. That is, they are inherited together and do not undergo Mendel’s Law of . Independent Assortment Back to “Beyond Mendel”

12. Gene Mapping • Genes are mapped on a chromosome based upon how frequently they cross over together. Grey Body Black Body Normal wings Small wings Back to “Beyond Mendel”

13. Polygenic Traits • Definition: Traits controlled by two or more genes • Examples: Skin color, height

14. Polygenic Traits Skin Color Height What about our height? Does it form the same pattern? Back to “Beyond Mendel”

15. Non-disjunction Disorders Definition: When members of a pair of homologous chromosomes fail to separate during Meiosis I – or – when sister chromatids fail to separate during Meiosis II. Examples: Down Syndrome, Turner’s syndrome, Klinefelter’s syndrome Meiosis I Meiosis II Gametes Back to “Beyond Mendel”

16. Prenatal Diagnosis: Amniocentesis 1. Amniotic fluid withdrawn Fetus (14 – 16 weeks) 2. Centrifuge Fluid Several weeks later Fetal Cells Placenta 3. Karyotype Cervix Uterus Cell culture

17. Prenatal Diagnosis: Chorionic villus sampling (CVS) 1. Suction tube inserted through cervix Fetus (8 – 10 weeks) Fetal cells Placenta Chorionic villi 2. Karyotype Several hours

18. Interpret these karyotypes Klinefelter’s syndrome

19. Interpret these karyotypes Sex: Male

20. Interpret these karyotypes Down Syndrome