Lecture # 15 02-26-13 Chapter 12 Chromosomes and Inheritance,Sex linkage (white eye in fruit flies, hemophilia, red-green colorblindness) Sex influenced (male pattern baldness) Autosomal dominant genes (Huntingtons, achondroplasia, polydactylism) Autosomal recessive genes (albanism, sickle cell, PKU, Tay Sachs) Aneuploidy Sex chromosomes (Turner, Klinefelter, XYY) Autosomes (Down syndrome) Chromosomal Abberations,Sex Linked A gene located on a sex chromosome.,Thomas Hunt Morgan 1910 Columbia University - was the first scientist to associate a specific gene with a specific chromosome. White eyes in fruit flies.,Thomas Hunt Morgan b. 1866 d. 1945,Morgan worked with the fruit fly Drosophilia melanogaster,Sex Linkage A gene located on a sex chromosome,A father with the trait will transmit the mutant allele to all daughters but no sons.,A carrier female will pass the mutation to half her sons and half her daughters,If a carrier mates with a male with the trait, there is a 50% chance that each child born to them will have the trait, regardless of sex.,X- linked recessive disorders in humans,Hemophilia Red-green color blindness Duchenne muscular dystrophy,Hemophilia is the lack of one or more clotting factors (proteins) that participate in the clotting of blood.,Tracing the Russian revolution to Queen Victoria!,Red-green color blindness,Red green colorblindness is x-linked,Duchenne muscular dystrophy,Affecting around 1 in 3,600 boys, which results in muscle degeneration and eventual death.The disorder is caused by a mutation in the dystrophin gene, located on the human X chromosome, which codes for the protein dystrophin, an important structural component within muscle tissue,Dominant genes 1.Huntingtons disease 2. Achondroplastic dwarfism 3. Polydactylism,Huntington disease a dominant genetic disorder,Huntington,Degeneration of the CNS in adult after age 30 Irritability, involuntary movement progresses to constant thrashing and writhing Terminal 5-15 years after onset,Scientists have discovered that the abnormal protein produced by the Huntingtons disease gene, which contains an elongated stretch of amino acids called glutamines, binds more tightly to HAP-1 than the normal protein does. This molecular partnership may contribute to the debilitating symptoms associated with the disease.,The peoples of lake Maracaibo Venezuela,Arlo Guthrie,Achondroplasia (dwarfism) Short stature long trunk and shortened limbs. Defective protein called “fibroblast growth factor receptor”,Achondroplasia is a genetic disease. This means that a gene that directs a specific process in the body does not work properly. In this particular condition, a protein in the body called the “Fibroblast Growth Factor Receptor“ begins to function abnormally. The result is that the growth of bones, which normally occurs in the cartilage of the growth plate, is slowed. This leads to shorter bones, abnormally shaped bones, and shorter stature.,Polydactylism (six fingers),Abnormal chromosome number (aneuploidy),Autosomes Down syndrome (trisomy 21) Sex Chromosomes Turner syndrome (XO) Klinefelters syndrome (XXY) Super male (XYY),Nondisjunction Down syndrome,Barr Body Inactivated X chromosome. Females have one Barr body in their nucleus. Male nuclei do not have Barr Bodies ( sex chromatin),Turner syndrome 1/5000 female births,One X no Y 45 chromosomes Barr body negative Klinefelter Syndrome 1/2000 male births XXY or XXXY 47/48 chromosomes Barr body positive XYY Male 1/1000 general male population 1/50 institutionalized males,A calico cat (a male calico is xxy),Sex determination,Sex influence Male baldness,Have a great day!,study,Pedigree chart,