1. Gregor Mendel “The Father of Genetics”
Chapter 10, Sections 1 and 2

2. Gregor Mendel ( )
An Austrian monk who used a scientific approach to study inheritance, giving birth to GENETICS (the study of heredity)
There was no knowledge of genes or DNA at the time; Therefore, Mendel’s refers to “factors” (today called genes)
His success, in part, came from his choice to use pea plants in his study
Contrasting traits or characteristics
Reproduce sexually, quickly, and have many offspring
Accessible and easy to handle

3. Controlled Reproduction
Stamen(♂) produces pollen
Carpel(♀) produces ovules (eggs)
Removing immature stamen prevents self-fertilization

4. Mendel’s 7 Traits of Pea Plants

5. In The Garden…
Mendel identified stocks of plants that were TRUE-BREEDING for a particular trait
Tall Plant  self-fertilization  All Tall Offspring
Mendel cross-fertilized two true-breeding plants with contrasting characteristics
(ex: purple flowers and white flowers)
He called them the P generation (for Parental)
What do you think the offspring looked like?

6. He called the F1 generation HYBRIDS
Mendel’s F1 Generation
F1 (for Filial) or “son” in Latin!
The offspring were
100% Purple Flowering
Mendel repeated this experiment and observed similar results with all 7 of the traits he studied!
He called the F1 generation HYBRIDS

7. A Second Generation
Mendel let the F1 generation self-fertilize and created a F2 generation
The white-flowering trait reappeared in the 2nd Generation!!
(3 Purple to 1 White)

8. Mendel’s Principles (in modern terms)
There are different forms of genes called alleles
Ex: Gene: height
Alleles: tall, dwarf
Genes are inherited in pairs, one allele from each parent
Homozygous: identical alleles
Heterozygous: different alleles
In a hybrid, only the dominant allele (T) will be expressed (or seen). The other allele is recessive (t).
Alleles segregate (separate) from each other during gamete formation and rejoin during fertilization to make the offspring

9. Principle of Segregation
What process segregates the alleles during gamete formation???

10. MEIOSIS!!

11. Punnett Squares
A diagram that can be used to show the potential outcome of a genetic cross

12. Genotype and Phenotype
Organisms with the same PHENOTYPE (physical appearance) may not have the same GENOTYPE (genetic make-up)
Purple Flowers (PP) Purple Flowers (Pp)
How do you determine the genotype of an organism with a dominant trait?

13. Test Cross
Cross the dominant (unknown genotype) with the recessive (known genotype)
50% Green
50% Yellow
100% Green

14. Mendel’s Principle of Independent Assortment
Mendel also looked at two-factor crosses or DIHYBRID crosses
Traits sort independently from one another during gamete formation

15. Mendel’s F1 and F2 Two-Factor Cross