Additional Punnette Squares

Genetic Disorders: The harmful effects produced by inherited mutations. Mutations:  *are changes in genetic material  *occurs when a gene is damaged, copied incorrectly, or a faulty protein was made

Examples of Genetic Disorders  Sickle Cell Anemia – autosomal recessive (red blood cells are sickle-shaped and oxygen is not carried to cells)  Cystic Fibrosis – autosomal recessive (production of thick sticky mucus – affects lung)  Huntington’s Disease – autosomal dominant (neurodegenerative disorder – nerve cells start to degenerate)  Hemophilia – sex linked recessive (rare bleeding disorder – blood does not clot properly)

 Tay Sachs– autosomal recessive (destroys nerve cells in the brain and spinal cord)  Phenylketonuria (PKU)– autosomal recessive (causes intellectual and developmental disabilities because body cannot break down the amino acid - phenylalanine)  Colorblindness– sex-linked recessive (a deficiency of color vision; have difficulty in distinguishing certain colors)

 Genetic Counseling – is a form of medical guidance that informs people about genetic problems that could affect them or their offspring  Genetic Therapy – allows scientists to correct certain recessive genetic disorders by replacing defective genes with copies of healthy ones

Sickle Cell Anemia  Sickle cell anemia is an autosomal recessive disorder. Jane is normal and does not carry the gene whereas here husband does have the disease. What percentage of their children will have sickle cell anemia? S ssss Ss 0%

Sickle Cell Anemia  Sickle cell anemia is a recessive autosomal disease. Michael and Kia are expecting their first child. Kia is a carrier of sickle cell but Michael is not. They see a genetic counselor who tells them that the probability that their child will be a carrier of sickle cell is ___ %. The probability that the child will have sickle cell is _____ %. S SsSs SS Ss 50 0

Huntington’s is a dominant disorder.  Suppose that a man with two children, aged 15 and 17, develops Huntington’s disease at age 50. The man is heterozygous and his wife does not have the disease. What are the chances that the children will have this disease? H h hhhh hh Hhhh 50 % When a disorder is autosomal dominant, can there be any carriers? No !!

Huntington’s is a dominant disorder.  Joe and his wife Betsy are both heterozygous for Huntington’s. Their children have a ___ % chance of having Huntington’s and a ___ % chance of being normal. The probability that their child will be a carrier of Huntington’s is _____ %. H h HhHh HHHh hh

Tay Sachs is autosomal recessive.  Janet and Lee are both heterozygous for Tay Sachs disease. What are the odds that their first child will be a carrier of Tay Sachs? ______% What are the chances the child will have Tay Sachs? _____ % What are the odds that their child will be normal? ____% T t TtTt TT Tt tt

Colorblindness is x - linked recessive.  Jim’s father is color blind and his mother has the gene for color-blindness but has normal color vision. What are the odds that Jim is color blind? ___ % How about his sister, Sarah? What are her chances of being color blind? ___ % What are her chances of being a carrier of color-blindness?___ % Xc Y Xc X XcXc XcY XcX XY 50

Phenylketonuria (PKU) is autosomal recessive.  Jane has PKU. Her husband, Darryl, neither has the gene or is a carrier. What are the chances that their children will have PKU? ____ % Not have PKU? _____% Be a carrier of PKU? ___ % p PPPP Pp 0 100

Blood Types and Multiple Alleles  Blood type inheritance is somewhat complicated, with three forms of the gene and 4 possible phenotypes. Suppose that a man with heterozygous blood type B marries a woman with heterozygous blood type A. What are the possible blood types of their children? ___________________ A O BOBO AB BO OO AO AB, A, B, O

Cystic Fibrosis is an autosomal recessive disease.  Suppose that a man with a family history of CF marries a woman with no history of the disease. The woman has no genes for CF while the man is a carrier (heterozygous) and does not have the disease. If these people become parents, what are the chances that their children will have CF? C c CCCC CC Cc CC 0%