1st Edition Psych 350 Lecture 5 Outline of Last Lecture Genetics Outline of Current Lecture II Meiosis III Genotype IV Autosomal Recessive Disorders V Autosomal Dominant Disorder VI Sex Linked Diseases Current Lecture Egg cell and sperm cell gametes meiosis process of recombination little bits of homologous chromosomes are swapped dipody genotype alleles on chromosomes brown hair chromosome and blonde hair chromosomephenotype outward expression actual color of hair two alleles the same homozygous two brownbrown allele on one chromosome and blonde on the other heterozygous carrier carry disease but don t show recessive trait non dominant both traits have to be homozygous for the trait if both father and mother are carriers of the trait then the child can have red hair 1 4 chance autosomal recessive inheritanceneed two copies of recessive gene to showautosomal recessive disorders cystic fibrosis metabolic disorder that can be fatal incidence 1 3000 need to inherent from mother and father carrier PKU metabolic disorder phenylalanine levels get higher and higher and gets to a point where it is toxic and then causes brain damage 1 10000 treatment is to remove phenylalanine from diet feed them food without it sickle cell anemia defect in clearing of oxygen in the bloodcommon in African Americans and southern Mediterranean countries like Greece not fatal but painful tay sachs disease jews of European descent and French Canadians untreatable fatal in infancy and early childhood first developed genetic testing for 30 50 years ago if two people got married and both carrier they would know autosomal dominant disease only need one copy of gene to show effects less common because if you have the gene then you get the disease and die Huntington s disease 1 in 20 000disorder does not show up until 30 or 40s already based on gene to children neurofibromatosis type1 1 in 3500 23rd chromosome pair x and y chromosome x chromosome is small and has few genes on it inheritance is different than the autumnal disease sex link disorders males get the disorder more than the girl red green color blindness 1 in 20 males gene involves is on the x chromosome example father has x and y chromosome no color blindness mother has 2 x chromosome one gene with red green colorblindness the male child has a 1 4 chance to be color blind the female child has a 1 4 chance to be a carrier hemophilia disorder of clotting in the blood1 in 4500 most common in boys treatable by providing the factor the is missing in the blood that aids clotting muscular dystrophy duchene missing protein important to muscle function aneuploidy abnormal number of chromosomes down syndrome 3 chromosome for 21 1 in 600 incidences increase as mothers age increases trisomy 21 usually have heart disorder can have three of any chromosome in the fetus and it will just die involve sex chromosomesturner s syndrome XO girl has one x chromosomes instead of two not severe triple x syndrome extra x girls klinergelter xxy xyy syndrome fragile x syndrome major causes if intellectual impairment sex link pattern where it is common i boys photo on next slide end looks bent or broken problem where there is extra inserted nucleotides