Mendelian Inheritance III Flashcards
Phenotype
overall genotype and unique environmental history
Ex: hydrangeas are pink in basic soil and blue in acidic soil
Norm of reaction
the way in which the environmental distribution is transformed into the phenotypic distribution for a given phenotype
Is it possible to predict the phenotypes of different genotypes in new environments?
No because norm of reaction curves of different genotypes in new environments
Pedigree
a family tree that describes the interrelationships of parents and children across generations
Rare autosomal dominants
-Every affected person has an affected parent
-About 1/2 of offspring of an affected parent are also affected
-Usually occurs in both sexes
Rare autosomal recessives
-Affected people usually have two parents who are not affected
-In affected families, about 1/4 of children of unaffected parents are affected
-Usually occurs in both sexes
Dominantly Inherited Disorders
-homozygous or heterzygous
-Ex: achondroplasia, Huntington’s Disease
Achondroplasia
-dominantly inherited disorder
-a form of dwarfism
-homozygosity is lethal
Recessively Inherited Disorders
-ONLY homozygous
-Ex: albinism, CF, hemochromatosis, phenylketonuria, spinal muscular atrophy
Sickle Cell Disease
-caused by a substitution of a single amino acid in the hemoglobin protein in RBCs
-affects 1/400 African Americans
-reduction against malaria symptoms
Symptoms of Sickle Cell Disease
physical weakness, pain, organ damage, and even paralysis
Sickle Cell Disease alleles
-2 sickle-cell alleles: ONLY sickled RBCs
-1 sickle-cell and 1 normal allele: Sickled and normal RBCs (carrier)
Carrier
heterozygous individuals who carry the recessive allele for a disorder but are phenotypically normal
Why are recessively inherited disorders more common than dominantly inherited?
Because carriers of recessively inherited disorders are phenotypically normal
Why do inherited disorders show variable frequency in different human populations?
Because historical geographic isolation of different human populations