Mendelian GeneticsBiology

Gregor Mendel

Gregor Mendel was an Austrian monk who studied the inheritance patterns in pea plants. His knowledge of statistics allowed him to make very accurate studies of seven traits in peas and how they were passed from one generation to the next. He began the study of genetics and is considered the Father of Genetics

Gregor Mendel

Mendel started with parental generations (P) that he knew were pure strains (produced offspring with the same traits). Then he crossed parents with different traits and recorded the numbers and types of the offspring (F1 generation). A cross of two of the F1 generation results in the F2 generation and so on.

Mendel’s Findings

Due to his observations, Mendel decided that there must be two factors controlling each trait. He concluded that there was a dominant (A) and a recessive (a) form of each trait.

Each of these forms is now called an allele.

– Dominant – Expressed.

– Recessive – Masked by the dominant allele.

Mendel’s Law’s

Law of Segregation – A pair of factors is separated or segregated during the formation of gametes (meiosis).

Law of Independent Assortment – Factors for different traits are distributed to gametes independently from one another.

Genetics Vocabulary

Genotype – The genetic makeup of an organism; the letters (AA, Aa or aa).

Phenotype – The appearance of the organism due to the genotype (red, pink, or white flowers).

Homozygous – Having two of the same alleles for a trait.– Homozygous dominant – AA

– Homozygous recessive – aa

Heterozygous – Having two different alleles (Aa).

Genetics Vocabulary

Product Rule of Probability – The probability of two events happening simultaneously is equal to the product of the probabilities of the two happening separately.