Father of Genetics

Gregor Mendel

Gregor Mendel is considered by many to be the “Father of Genetics”

He was a monk from a monastery in Austria in the 1800’s.

Discovered genes

Why Pea Plants?

Mendel studied pea plants because they were self-pollinating.

Pea plants were good for study because they grow fast and have visual traits.

Mendel’s Experiments

Mendel started his experiment with purebred (homozygous) plants.

A purebred plant is one that always produces offspring with the same form of a trait as the parent.

Mendel’s Experiment

Mendel’s Second Experiment

Mendel then took the offspring in the F1 generation and crossed them.

These results also surprised Mendel.

The offspring in the second filial generation or (F2) were a mix of tall and short plants.

He found that 75% were tall and 25% were short.

Genes and Alleles

The factors that control traits are called genes. Different forms of a gene are called alleles For example the gene for stem height can be

determined by a short allele or tall allele.

Dominant and Recessive Alleles

The dominant allele is one whose trait always shows up

A recessive allele is one that will be masked whenever the dominant allele is present and will only show up if there are two recessive alleles.

Using Symbols

Dominant alleles are represented with a capital letter. Tall stems = (T)

Recessive alleles are represented with the same letter, only its lowercase. Short stems = (t)

Understanding Mendel’s Crosses

Mendel’s P generation plants were purebred, meaning they had two of the same alleles.

(TT) = “homozygous tall” (tt)= “homozygous short”

The F1 offspring received one allele from each parent making the allele combination: (Tt)

(Tt) is a hybrid (heterozygous) organism that has both the dominant and the recessive allele for a trait.

Mendel’s Contribution

Many scientists thought that Mendel’s explanation of heredity was oversimplified.

Because of this, his work was forgotten for 34 years.

However years later, three other scientists confirmed his findings and he became known as “The Father of Genetics”