Chapter 12 - Patterns of Inheritance Flashcards
What evidence contradicted the idea that traits are directly passed from parent to offspring?
Crossing hybrids led to some offspring resembling original strains rather than the hybrid strains.
Why did Gregor Mendel choose to study pea plants?
- pea hybrids could be produced
- many pea varieties available
- peas are small and easy to grow
- can self-fertilize or be cross-fertilized
What were the 7 characters Mendel studied in his experiments?
- purple vs white flowers
- yellow seeds vs green seeds
- round seeds vs wrinkled seeds
- green pods vs yellow pods
- inflated pods vs constricted pods
- axial flowers vs terminal flowers
- tall plants vs dwarf plants
Mendel’s experimental method:
- produce true-breeding strains for each trait he was studying
- cross-fertilize true-breeding strains having alternate forms of trait
- perform reciprocal crosses as well - allow hybrid offspring to self-fertilize and count # of offspring showing each form of the trait
Monohybrid cross:
a cross to study only 2 variations of a single trait
F1 generation (1st filial generation):
offspring produced by crossing 2 true-breeding strains
F2 generation:
offspring resulting from the self-fertilization of F1 plants
Dominant:
the form of each trait expressed in the F1 plants
Recessive:
the form of the trait not seen in the F1 plants
Dominant to Recessive ratio in F2 plants (phenotype):
3:1
Genotype ratio in F2 plants:
1 true-breeding dominant: 2 non-true-breeding dominant: 1 true-breeding recessive
Gene:
information for a trait passed from parent to offspring
Alleles:
alternate forms of a gene
homozygous
having 2 of the same allele
heterozygous
having 2 different alleles
genotype
total set of alleles of an individual
homozygous dominant
PP
heterozygous
Pp
homozygous recessive
pp
phenotype
outward appearance of an individual
Principle of Segregation
two alleles for a gene segregate during gamete formation and are joined at random, one from each parent, during fertilization
The genotypes of potential offspring can be represented within a(n) ____________.
punnett square
Dihybrid cross:
examination of 2 separate traits in a single cross
Principle of Independent Assortment
(in a dihybrid cross) the alleles for each gene assort independently
The probability of 2 mutually exclusive events occurring simultaneously
rule of addition
The probability of 2 independent events occurring simultaneously
rule of multiplication
test cross
a cross used to determine the genotype of an individual with dominant phenotype; cross individual w/ unknown genotype w/ a homozygous recessive
polygenic inheritance
when multiple genes are involved in controlling the phenotype of a trait
pleiotropy
an allele which has more than one effect on the phenotype ex. cystic fibrosis or sickle cell anemia
incomplete dominance
the heterozygote is intermediate in phenotype between 2 homozygotes (blending)
codominance
heterozygote shows some aspect of the phenotypes of both (equally shown)
Sugars exhibited in type A blood:
galactosamine
Sugars exhibited in type B blood:
galactose
Sugars exhibited in type AB blood:
galactosamine and galactose
Sugars exhibited in type O blood:
none
epistasis
one gene can interfere with the expression of another gene (lab coat color)
