1. Gregor Mendel “The Father of Genetics”
Studied peas: easy and quick to breed, can control mating

2. Mendel’s Pea Plants Plant Height Seed Color Pod color Green Yellow
Short
Green
Yellow
Tall
Pod Shape
Seed Shape
Wrinkled
Round
Smooth
Pinched

3. Mendel’s Experiments Mendel mated “purebred” plants. (Homozygous)
Offspring always looked like parents. X
Short Offspring
Purebred Short Parents X
Purebred Tall Parents
Tall Offspring

4. Mendel’s First Experiment
Mendel crossed purebred plants with opposite forms of a trait (like tall x short). X
Short
Tall
All Offspring Tall!

5. Mendel’s Second Experiment
Mendel then crossed two of the offspring from the first experiment. X
Tall offspring from 1st experiment
3⁄4 Tall & 1⁄4 Short
The short trait showed back up

6. Dominant and Recessive Genes
Mendel concluded that one factor masked the other factor.
Alleles that mask or hide other alleles, such as the “tall” allele, are said to be dominant.
A recessive allele, such as the short allele, is masked, or covered up, whenever the dominant allele is present.

7. Mendel’s Law of Segregation
Traits exist in different forms and one individual contains 2 alleles for each trait.
But only one factor is passed down when egg or sperm are formed—at random. (50-50 chance)

8. What happens if you cross plants heterozygous for 2 traits?X
Yellow Allele
Green Allele X
Round seed Allele
Wrinkled seed allele
Yellow seeds are dominant over green and round seeds are dominant over wrinkled seeds.

9. The first batch of seeds was all round and yellow.
But when those plants produced seeds, Mendel got round yellow, round green, wrinkled yellow, wrinkled green.

10. Law of Independent Assortment
Each pair of alleles separate independently of each other in the production of eggs and sperm.
So you can get a dominant allele for one trait and dominant for the second—or equally likely, recessive for the second. It’s random for each trait

11. Thanks, Gregor Mendel