1. Genetics
A. The work of Gregor Mendel
1. Monohybrid crosses
2. Dominant and recessive alleles
3. Law of Segregation
B. Mendel and meiosis

5. Who was this Mendel and what the heck is he doing in a monastery?
born in 1822
trained himself to be a naturalist early in life
worked as a substitute science teacher
failed the qualifying exams to be a regular high school teacher!
joined a monastery in Brunn, Austria
sent to Vienna U. to study science and math

7. MendelWeb
Mendel’s first published work: "Versuche über Pflanzen-Hybriden“ or Experiments in Plant Hybridization was a landmark in clarity and insight!
Trained as a mathematician and a biologist, he figured out the laws of inheritance… mathematically!!

8. The work of Gregor Mendel
worked with pea plants…
…he called them his children!
Why pea plants???
There was a long-standing tradition of breeding pea plants at the monastery where Mendel lived and worked

9. So…they were readily available and they come in lots of varieties!
…there were plants with different flower colors, seed color, flower position etc..

10. ‘Brother Greg... We grow tired of peas again!!!’

11. And best of all… Pea plants flowers can reproduce by themselves
This allowed Mendel to see if strains were true breeding and to produce hybrids

12. How Mendel made hybrids…
He’d then tie little bags around the flowers to prevent contact with stray pollen.

13. Mendel’s hybridization experiments…
Monohybrid crosses:
Parental Generation
True-breeding purple flower
True-breeding white flower x
All purple flowers (the hybrids)
F1 generation
Allowed F1 offspring to self-fertilize
F2 generation
705 purple
224 white

15. The results of Mendel’s monohybrid crosses led him to propose…
All organisms contain two “units of heredity” for each trait (alleles).
Dominant and recessive alleles…
…and organisms can have any combination of the two alleles (2 dominants, 2 recessives or a mixture 1 dominant and 1 recessive).
The Law of Segregation – during gamete formation, alleles separate randomly into separate gametes.

16. A bit of genetic jargon…
phenotype vs. genotype
What the organism looks like
What alleles the organism has - its genetic makeup

17. More jargon… homozygous vs. heterozygous P 2 of the same alleles:
PP or pp
2 different alleles: Pp p

18. A Punnett square

19. A Punnett square… Gametes from one parent p P PP Pp P
Gametes from other parent
purple
purple pp Pp p
purple
white
Ratio: 3:1 or ¾ purple, ¼ white