Dapo Adegbile Nevin Varghese Victor Veras

1. DapoAdegbileNevin Varghese Victor Veras 1-28-10 Period 2

2. Summary of Polydactyly • Polydactyly is a condition in which a person has more than five fingers per hand or five toes per foot. • Polydactyly occurs in the womb; instead of developing only one thumb and four fingers an extra finger is added • Usually the hand is formed in the womb and when it is being split it is made into 4 fingers, 1 thumb. However sometimes an extra split occurs and abnormal number of fingers is produced • It is a autosomal dominate characteristic

3. Chromosome Disorder is Located on • The cause of the disorder is usually found on chromosome 13. • However for some cases it is not known • There is another gene or chromosome that the mutation could happen in that could cause polydactyly

4. Mode of Inheritance • Polydactyly is autosomal dominant. • Autosomal dominant means that an offspring can get this disease by having it passed down from just one parent. • Polydactyly occurs because of genetic disorders or errors in fetal development. • Polydactyly can also be a symptom for another disease. • Ex. – Bardet-Biedl syndrome • Ex. – Bloom’s syndrome • Ex. – Jeune’s thoracic dystrophy syndrome

5. What are Alleles? • A person has two alleles per gene • You get one of the two alleles in a gene from your father and the other from your mother • Recessive alleles are represented by the letter of the characteristic in lower-case form • Dominant alleles are represented by the letter of the characteristic in capital • R – Dominant • r – Recessive • The dominant alleles and the recessive alleles both represent two different possible characteristics. • The “characteristic” will be dominant if the gene has one dominant allele or two dominant alleles • The “characteristic” will be recessive if the gene has two recessive genes only

6. Punnent Square – Demonstration G g w w h h G g W W h h Heterozygous Homozygous

7. Probability of Disease occurring G g • Ratio • 1GG 2Gg 1gg G g • Percentage • 25% -GG 50% - Gg 25% - gg • 75% chance of getting Polydactyly • 25% chance of not getting Polydactyly

8. What the letters mean G g • GG – two dominant alleles • Gg – one dominant allele and one recessive allele • gg – two recessive alleles G g • Phenotype • GG = Recieve polydactyly • Gg = Receive polydactyly • gg = Normal amount of fingers • Top – Father • Left – Mother • Genotype • GG = Homozygous dominant • Gg = Heterozygous dominant • gg = Homozygous recessive

9. Genotype and Phenotype possibility G g G g • Phenotype • - Ratios- 3 for polydactyly : 1 for normal • - Percentage – 75% chance of polydactyly • 25% chance of normal # of f fingers • Genotype • - Ratios- 1 GG : 2 Gg : 1 gg • - Percentages- 25% GG : 50% Gg : 25%gg

10. Student Practice G g • Genotype • Ratio – 1 GG; 2 Gg; 1gg • Percentage – 75% chance receive disease • 25% chance of not getting disease G g GG Gg • Phenotype • Ratio – 3 with Polydactyly; 1 without Polydactyly • Percentage – 75% of getting Polydactyly Gg gg

11. 3 Generation Hypothetical Pedigree – Autosomal Dominant Female – circle Male – Square All green – homozygous recessive gene, person doesn’t have the disease, person has 2 healthy alleles Half green, half black (or star) – heterozygous gene, person has the disease because you only one dominant gene with the disease to get it All black homozygous dominant. Has the disease.

12. Student Practice • Key – • circle – female • square – male • shaded in (black) – two dominant alleles • not shaded (red) – two recessive alleles • half shaded – one dominant and one recessive allele

13. Questions???????? • If two parents are homozygous dominant, how likely would it be for a child not have the disease? • If one parent is homozygous dominant but another is homozygous recessive, is it possible for one of the children not to obtain the disease? • If one parent were heterozygous dominant and homozygous recessive, how likely is it for a child to get the disease? • 0% child would wind up homozygous dominant • Each of the children will wind up heterozygous dominant 50%