Chapter 1: Mendel's Principles of Heredity

genetics

science of heredity

heredity

the way that genes transmit traits from parents to offspring across generations

phenotype

observable characteristics

alleles

alternate forms of a gene

independent assortment

alleles of one gene separate into gametes randomly with respect to alleles of other genes

gametes

reproductive cells containing only one copy of each gene

gene

the heritable entity that determines a characteristic

segregation

the separation of the two alleles of a gene into different gametes

heterozygote

an individual with two different alleles of a gene

dominant

the allele expressed in the phenotype of the heterozygote

F1

offspring of the P generation

testcross

the cross of an individual of ambiguous genotype with a homozygous recessive individual

genotype

the alleles an individual has

recessive

the allele that does not contribute to the phenotype of the heterozygote

dihybrid cross

a cross between individuals both heterozygous for two genes

homozygote

having two identical alleles of a given gene

law of dominance

recessive alleles will always be masked by dominant alleles

law of segregation

two alleles of a gene separate during gamete formation

law of independent assortment

genes for different traits separate from one another during gamete formation

product rule

the probability that two independent events will occur is equal to the product of their individual probabilities

sum rule

probability of two mutually exclusive events occurring is the sum of their individual probabilities

antagonistic pairs

visibly different traits rather than continuous traits

pedigree

orderly diagrams of a family's relevant genetic features

Huntington's disease

rare dominant trait disease

vertical

rare dominant trait pattern of inheritance

cystic fibrosis

rare recessive trait disease

horizontal

rare recessive trait pattern of inheritance

3:1

ratio of progeny phenotypes in a cross between monohybrids

1:2:1

ratio of progeny genotypes in a cross between monohybrids

1:0

all progeny are the same phenotype

9:3:3:1

ratio of progeny phenotypes in a dihybrid cross