Inheritance Patterns
Chapter 5 - 6
7 Traits of Pea Plants studied by Gregor Mendel
- Stem length (Tall/short)
- Pod shape (inflated/pinched)
- Seed colour (yellow/green)
- Seed shape (round/wrinkled)
- Flower position (Axial/top)
- Flower colour (Purple/white)
- Pod colour (Green/yellow)
Mendel’s monohybrid cross experiments proved the existence of dominant +
recessive traits
Cross - Fertilization go a female and male gamete where both are of specific
genetic origins (cross-pollination)
Monohybrid Cross
- 1 trait is monitored
Trait - Specific characteristic of an organism
- Ex. Flower colour
True breeding - Organisms with the same traits even after generations
(homozygous)
- Antonym: Heterozygous (different traits)
P generation - Parental generation
F1 generation - First filial; offspring of P generation
F2 generation - Second filial; offspring of F1 generation
P1 GG x gg
, F1 Gg
P2 Gg x Gg
F2 25% GG, 50%Gg, 25% gg
75% green, 25% yellow
3 : 1 (Mendelian ratio)
Law of Segregation
-Everyone has 1 pair of alleles for any trait but during reproduction, only 1
allele is passed to the next gen (each gamete has 1 allele)
- There are dominant and recessive alleles
- Dominant - Always appears as the phenotype if at least 1
- Uppercase
- Can be homozygous dominant (AA)
- Recessive - Only appears as the phenotype if 0 dominant
- Lowercase
- Can be homozygous recessive (aa)
Heterozygous - 2 different alleles for a gene (Aa)
Genotype - Combination of alleles (genetic make-up)
Phenotype - Physiological traits (expression of genotype)
Test Cross - Cross between unknown genotype with homozygous recessive
If the parent is homozygous dominant, all offspring
phenotypes are the dominant color.
If the parent is heterozygous dominant, offspring
phenotypes 50% dominant color, 50% recessive color.
Dihybrid Cross
- 2 trait is monitored
RrYy x RrYy
9:3:3:1
RY : Ry : rY : ry
Chapter 5 - 6
7 Traits of Pea Plants studied by Gregor Mendel
- Stem length (Tall/short)
- Pod shape (inflated/pinched)
- Seed colour (yellow/green)
- Seed shape (round/wrinkled)
- Flower position (Axial/top)
- Flower colour (Purple/white)
- Pod colour (Green/yellow)
Mendel’s monohybrid cross experiments proved the existence of dominant +
recessive traits
Cross - Fertilization go a female and male gamete where both are of specific
genetic origins (cross-pollination)
Monohybrid Cross
- 1 trait is monitored
Trait - Specific characteristic of an organism
- Ex. Flower colour
True breeding - Organisms with the same traits even after generations
(homozygous)
- Antonym: Heterozygous (different traits)
P generation - Parental generation
F1 generation - First filial; offspring of P generation
F2 generation - Second filial; offspring of F1 generation
P1 GG x gg
, F1 Gg
P2 Gg x Gg
F2 25% GG, 50%Gg, 25% gg
75% green, 25% yellow
3 : 1 (Mendelian ratio)
Law of Segregation
-Everyone has 1 pair of alleles for any trait but during reproduction, only 1
allele is passed to the next gen (each gamete has 1 allele)
- There are dominant and recessive alleles
- Dominant - Always appears as the phenotype if at least 1
- Uppercase
- Can be homozygous dominant (AA)
- Recessive - Only appears as the phenotype if 0 dominant
- Lowercase
- Can be homozygous recessive (aa)
Heterozygous - 2 different alleles for a gene (Aa)
Genotype - Combination of alleles (genetic make-up)
Phenotype - Physiological traits (expression of genotype)
Test Cross - Cross between unknown genotype with homozygous recessive
If the parent is homozygous dominant, all offspring
phenotypes are the dominant color.
If the parent is heterozygous dominant, offspring
phenotypes 50% dominant color, 50% recessive color.
Dihybrid Cross
- 2 trait is monitored
RrYy x RrYy
9:3:3:1
RY : Ry : rY : ry
