1. Kristin Donadio, Grace Groeger, and Marie-Claire Langdon February 1 st, 2010 Period 9/10

2.  Destroys nerve cells in the brain and spinal cord  Infants’ development slows and muscles for movement weaken (around 3-6 months old)  Experience seizures, vision and hearing loss, intellectual disability, and paralysis  Usually only live into early childhood  Named after Warren Tay and Bernard Sachs  Rare, except common in Jewish heritage

3. CChromosome 15- the genes that code for Hex-A, an enzyme

4.  This disease is autosomal recessive.  This means each copy of the gene in each cell will have mutations.  Each of the parents have to carry the mutated gene for the child to have this disease.  The carrier of this gene will show no symptoms.  Tay Sachs disease is most common in people of eastern and central Europe, or of Jewish heritage. Also in French-Canadian communities of Quebec, the Old Order Amish community in Pennsylvania, and the Cajun population of Louisiana

5.  Alternate form of genes  Two alleles per gene, one from each parent  When alleles are different, the dominant allele will be expressed and recessive will be masked  X-linked: the gene causing the trait or disorder is on the x chromosome

6. Tt TTTt tt T T t T TtTt letters on the outside of the Punnett Square represent the parent’s alleles (genes). The alleles on top are the father’s, on the side are the mother’s Each punnett square shows the probability of one child having a certain trait t

7.  Ratios: - Homozygous Dominant: Heterozygous Dominant: Homozygous Recessive - 1:2:1 1TT;2Tt;1tt Percentages: -Homozygous Dominant: Heterozygous Dominant: Homozygous Recessive - 25% : 50% : 25% 25% TT :50% Tt : 25% tt TTTt tt T t Tt

8.  What the letters mean: ◦ T would represent the dominant allele that you don’t have Tay Sach’s ◦ t would then represent the recessive allele Tay Sach’s  Phenotype: ◦ TT= that you don’t have Tay Sach’s ◦ Tt= that you don’t have Tay Sach’s but you are a carrier of it ◦ tt= that you have Tay Sach’s  Genotype: ◦ GG= Homozygous Dominant ◦ Gg= Heterozygous Dominant ◦ gg= Homozygous Recessive TTTt tt T t Tt

9.  Phenotype: the appearance of an organism resulting from the interaction of the genotype and the environment. ◦ Ratios~ 3 possibilities’ of not having Tay Sach’s: 1 possibilities’ of having Tay Sach’s ◦ Percentage~ 75% possibilities’ of not having Tay Sach’s: 25% possibilities’ of having Tay Sach’s  Genotype: A combination of alleles situated on corresponding chromosomes that determines a specific trait. ◦ Ratio~ 1TT: 2Tt: 1tt ◦ Percentages~ 25% TT: 50% Tt: 25% tt TTTt tt T t Tt

10.  Genotype: ◦ Ratio~ 2 possibilities’ of not having Tay Sach’s: 2 possibilities’ of having Tay Sach’s ◦ Percentage~ 50% possibilities’ of not having Tay Sach’s: 50% possibilities’ of having Tay Sach’s  Phenotype: ◦ Ratio~ 2Tt: 2tt ◦ Percentage~ 50% Tt: 50% tt t t Tt Tttt Tttt

11. White: the person does not have the Tay Sachs gene or is only a carrier Blue: the person has both Tay Sachs genes SallyPaul SuePaul Jr. PeterSandyRoger Peter Jr. SallySueRoger Jr.

12. Key: Circle= Rectangle= Shaded= Not shaded= 1.How many people DO have Tay Sachs? How do you know? 3 people have the disease. The shapes that are blue indicate affected people. 2.Which generation has the most affected people? The 3 rd generation 3.If Jenny and Johnny had a child, what is the probability of their child to have Tay Sachs? Their child has a 100% chance of having the disease JennyJohnny female Male The person has Tay Sachs Does not have Tay Sachs gene or is only a carrier