Who started Who started it all?it all?

What is Genetics?

Genetics is the study of biological inheritance patterns and variation in

organisms

Mendel Background

Gregor Mendel was an Austrian Monk, born that worked and lived throughout the 1800s.

He was a physics teacher with a passion for plants, which he explored in the garden of his monastery.

What did Mendel Do?

Mendel worked with Pea Plants to establish the basic principles of genetics

He proved that traits are inherited as discreet units from parents and given to their offspring

He described how traits are passed between generations

What got Mendel Started?

He observed that some tall plants produce tall offspring, while other tall plants produce short offspring. He also noticed that some plants with yellow seeds produce offspring with yellow seeds while others produce white seeds.

(The event he observed is called inheritance)

How did he begin?

Mendel made three key choices when choosing to work with pea plants•Controlled breeding•Use of Purebred Plants•Use of “either/or” traits

Mendel examined 7 specific traits in pea plants:1.Seed Shape2.Seed Color3.Flower Color4.Flower Position5.Pod Color6.Pod Shape7.Plant Height

Mendel worked with pea plants because they self-pollinate

P (Parental) GenerationMendel crossed (mated) purebred pea plants that either had round or wrinkled peas. The result was the F1 generation

F1 (First Filial) GenerationThe F1 generation of peas were all round. There were no wrinkled offspring even though one of the parents had only wrinkled peas. Mendel decided to cross two offspring from the F1 generation. The result was the F2 generation

F2 (Second Filial) GenerationThe cross result in the F2 generation was that 75% of the peas were round and 25% of the peas were wrinkled.

The Experiment

The ResultsMendel concluded that even though the wrinkled trait physically disappeared in the F1 generation, that it had not truly disappeared. The wrinkled trait had been masked by the round trait. That is why the wrinkled trait reappeared in the F2 generation. He also noted that the traits reappeared in a 3:1 ratio

(3 round: 1wrinkled)

1. The Principle of Dominance and RecessivenessEach characteristic of a plant was controlled by some “factor”. The factors of different plants interacted when the plants reproduced. Depending on the factors involved, one may “mask” another. For example, when a plant with green pods is crossed with a plant who has yellow pods, the green pods appear in the offspring and yellow pods do not.We can say that the round pea characteristic is dominant and the wrinkled pea characteristic is recessive.

His First Conclusion

Principle of SegregationMendel said that the two factors for a characteristic separate during the formation of the egg and the sperm. Each egg cell and each sperm cell only gets ½ of the information. If they did not separate, then the new organism would have too many chromosomes.

His Second Conclusion

The Principle of Independent Assortment

Mendel noticed that when he crossed plants with two different characteristics, in the offspring of these plants, the traits did not necessarily travel together. For example, if you crossed a Tall Green seeded plant with a Short Yellow Seeded plant, both your tall and short plants can have Green seeds.

His Third Conclusion