simple dominance Medels experiments cross red and white and get either or NOT pink non Mendelian inheritance or incomplete dominance heterozygous genotype exhibits intermediate phenotype like pink ex presence of one dominant allele can sometimes just not provide enough pigment to get it all the way up to red so its pink blood types multiple allele system A and B code for two versions of enzyme O allele is mutated and does not code for a functional protein A and B are codominant if the individual has both A and B alleles he will be of AB blood group O is recessive so only the homozygous recessive individuals will have an O phenotype refers to presence or absence of a membrane glycoprotein called Rh single dominance pattern sickle cell anemia and sickle cell trait hemoglobin is defective giving red blood cells a sickled appearance a change in one amino acid in structure of hemoglobin makes it defective heterozygotes will present both types of hemoglobin sickle cell trait polygenic inheritance some traits determined by multiple genes ex skin color determined by at least 3 different genes epistasis products of two or more genes result in certain phenotype expression of one gene masks or changes expected phenotype of one or more other genes ex labs B black b chocolate yellow labs created through epistasis where another gene is in play E e pleiotropy single genes that have numerous different effects rather than just two ex fibrillin 1 which codes for a connective tissue protein Marfan syndrome multifactorial characteristics characteristics that are influenced by environmental as well as genetic factors norm of reaction range of phenotypic possibilities human genetic disorders following Mendelian pattern are least common most are recessive so heterozygotes are carriers autosomal chromosomes that are not sex determining sex linked v autosomal disorders sex chromosomes X and Y X is large and carries many genes unrelated to sex Y smaller and carries only genes containing instructions for maleness signals that instruct fetal gonads to develop as testes chromosome 1 is biggest and 22 is smallest aneuploidy condition of having too many or too few chromosomes which results from errors in meiosis maps that can be used to trace genetic traits through generations of individuals pedigrees males are squares females circles mated individuals connected by horizontal children connected by vertical branches expressing genetic trait are shaded used to determine if a trait being studied is dominant recessive or X linked HGPS progeria one case per 8 million live births autosomal dominant disorder accelerated aging caused in gene coding for lamina A protein involved in chromosome organization die in teens from stroke or heart attack not inherited but only appears as a random mutation