Mendelian Inheritance III

Question 1

Phenotype

Answer 1

includes physical appearance, internal anatomy, physiology, and behavior
Phenotype = Genotype x Environment
ex: flowers are pink in basic soil and blue in acidic soil

Question 2

Norm of Reaction

Answer 2

determines the way in which environmental distribution is transformed into the phenotypic distribution for a given genotype

distribution of environments (ex: temp) will be reflected biologically as a distribution of phenotypes (ex: size at maturity)

Impossible to predict the phenotypes of different genotypes in new environments

Question 3

Pedigree

Answer 3

family tree that describes the interrelationships of parents and children across generations

Question 4

General Rules about Pedigrees

Rare autosomal dominants

Answer 4

every affected person has an affected parent
about half the offspring of an affected parent are also affected
the phenotype usually occurs in both sexes

Question 5

General Rules about Pedigrees

Rare autosomal recessives

Answer 5

affected people usually have two parents who are not affected
in affected families, about 1/4 of the children of unaffected parents are affected
the phenotype usually occurs equally in both sexes

Question 6

Dominantly Inherited Disorders

Answer 6

can be homozygous or heterozygous
achondroplasia: a form of dwarfism, is a dominantly inherited disorder (homozygosity for the dominant allele is lethal)

Question 7

Recessively Inherited Disorders

Answer 7

show up only in individuals homozygous for the alleles (ex: albinism)
more common than dominantly inherited because carriers are phenotypically normal)

Question 8

Carriers

Answer 8

heterozygous individuals who carry the recessive allele but are phenotypically normal

Question 9

Sickle Cell Disease

Answer 9

caused by substitution of a single amino acid in the hemoglobin protein in RBCs
recessively inherited disorder

Question 10

Why is inherited disorders show variable frequency in different human populations

Answer 10

Due to the historical geographic isolation of different human populations

Question 11

Timeline

Answer 11

• meiosis is discovered
• Weismann germ plasm theory separates germs cells from somatic cells
• Boveri claims that chromosomes are the physical basis of inheritance
• Mendel’s paper was rediscovered and replicated
  *chromosomal theory of heredity