2ND QUARTER
MENDELIAN GENETICS
Genetics – the branch of biology concerned with study of inherited variation.
More specifically, the study of the origin, transmission, expression, and evolution
of genetic
information.
Heredity – the natural process by which physical and mental qualities are passed
from a parent to a child.
Gene - a discrete unit of inheritance which is believed to be carrying the hereditary
traits
Gregor Johann Mendel - “Father of Genetics”
- Developed the laws of inheritance
- Cultivated and tested some 28,000 pea plants.
Selected pea plants for study
1. Easy to grow, take little space, easily observable traits
2. Can be self - pollinated or cross-pollinated
3. Applied math with biology - probability and statistics
7 Characteristics of Pea Plants
Dominant allele Recessive allele
Purple flowers White flowers
Axial flowers Terminal flowers
Yellow seeds Green seeds
Round seeds Wrinkled seeds
Smooth pods Constricted pods
Green pods Yellow pods
Tall plants Short plants
First set of experiments - crossed purebred tall plants with
purebred short plants. (TT x tt)
Phenotypic Ratio – 4:4; all tall
Genotypic Ratio – 4Tt
Purebred - organism that always produces the same trait in offspring also called
true breeding.
P generation – purebred characteristics; parental generation; homozygous
F1 generation (First Filial-son) - Offspring of the P generation
Alleles - alternative forms of genes
Trait – any detectable phenotypic variation of inherited character; specific
characteristic, such as seed color or height
MENDELIAN GENETICS
Genetics – the branch of biology concerned with study of inherited variation.
More specifically, the study of the origin, transmission, expression, and evolution
of genetic
information.
Heredity – the natural process by which physical and mental qualities are passed
from a parent to a child.
Gene - a discrete unit of inheritance which is believed to be carrying the hereditary
traits
Gregor Johann Mendel - “Father of Genetics”
- Developed the laws of inheritance
- Cultivated and tested some 28,000 pea plants.
Selected pea plants for study
1. Easy to grow, take little space, easily observable traits
2. Can be self - pollinated or cross-pollinated
3. Applied math with biology - probability and statistics
7 Characteristics of Pea Plants
Dominant allele Recessive allele
Purple flowers White flowers
Axial flowers Terminal flowers
Yellow seeds Green seeds
Round seeds Wrinkled seeds
Smooth pods Constricted pods
Green pods Yellow pods
Tall plants Short plants
First set of experiments - crossed purebred tall plants with
purebred short plants. (TT x tt)
Phenotypic Ratio – 4:4; all tall
Genotypic Ratio – 4Tt
Purebred - organism that always produces the same trait in offspring also called
true breeding.
P generation – purebred characteristics; parental generation; homozygous
F1 generation (First Filial-son) - Offspring of the P generation
Alleles - alternative forms of genes
Trait – any detectable phenotypic variation of inherited character; specific
characteristic, such as seed color or height
