The Work of Gregor Mendel Or, why peas are awesome

The Man Gregor Mendel (1822-1884) was a monk who lived in what is now the Czech Republic. He was a painfully shy man who loved science. He tended the Abbey garden and found time to do breeding experiments on the common pea plant. He found 7 pea plant traits that he wanted to experiment with.

Pea Traits Gregor Mendel found that peas displayed these traits in one way or another. Never a mixture.

Pea Traits For example, if a pea plant had white and wrinkled pods, all its pods were white and wrinkled.

Why were peas totally awesome for his experiments? Because they could fertilize themselves. Remember: Fertilization is when male and female reproductive cells join to make a new cell. Question: What ploidy are the male and female reproductive cells? What ploidy is the newly formed cell?

The Humble Pea

Fertilization

Vocab Review! Fertilization: When male and female sex cells unite to form a new cell. Trait: A specific characteristic of an individual Genes: Factors passed from parent to offspring that code for traits.

How do you start an experiment that will change modern genetics? Mendel started with true-breeding plants. These plants could cross with themselves and always produce offspring that looked identical to the parent.

What does true breeding mean? True breeding plants always produce babies that look like them. Always. All their genes are the same at every place on the chromosome. These are very important in agricultural science.

Traits and alleles Traits:

Traits and Alleles Gene: Fur color Allele: Black, brown or white The alleles can be abbreviated with single letters and the allele (or genetic) makeup is called the genotype. Coat color is an obvious trait, and is called the phenotype.

Alleles and Dominance In his experiments with peas, Mendel found that some alleles were dominant while others were recessive. A dominant allele is always expressed when it’s present. A recessive allele is only expressed when it’s partner is another recessive allele.

Alleles and Dominance

Dominance Rock, paper scissors The principle of dominance states that some alleles are dominant and others are recessive. What does that mean in plain language? Shorthand for writing alleles, P, F1 and F2 Generations, homozygous, heterozygous, and hybrid cross.

Segregation Gametes How many copies of each chromosome does each one have?

Probability: When you work a Punnett square, you can use math to predict the outcome.