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11-1 The Work of Gregory Mendel Flora I. Genetics Genetics – the study of heredity Essential to understanding biology.

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Presentation on theme: "11-1 The Work of Gregory Mendel Flora I. Genetics Genetics – the study of heredity Essential to understanding biology."— Presentation transcript:

1 11-1 The Work of Gregory Mendel Flora I

2 Genetics Genetics – the study of heredity Essential to understanding biology

3 Mendel Mendel knew the following: Each part of each flower produces pollen (anther) Other portions produce female reproduction cells The two join and fertilization occurs Gametes – sex cell Fertilization – male and female reproduction cells join to form a new cell True-breeding – if allowed to self-pollinate, they would produce offspring identical to themselves

4 Genes and Dominance Mendel studied plant traits Trait – specific characteristic of an organism Ex: seed color, plant height, etc. Mendel studied 7 traits: Seed shape Seed color Seed coat Pod shape Pod color Flower position Plant height

5 Cont. Mendel crossed plants with these seven contrasting traits and studied their offspring Parents – called P generation Offspring – called F 1 generation A cross between parents with different traits are known as hybrids

6 Mendels Two Conclusions 1. Biological inheritance is determined by factors that are passed on from one generation to the next These traits are called genes Genes – sequence of DNA that codes for a specific protein thus determining the trait Some genes have contrasting forms called alleles Alleles – one of a number of different forms of a gene

7 Cont. Mendels Two Conclusions 2. The principal of dominance states that some alleles are dominant and others are recessive An organism with a dominant allele for a specific trait will always exhibit that form of that trait. Recessive alleles will only exhibit that trait when the dominant allele is absent Ex: Mendels Experiment

8 Segregation Did the alleles present in the P generation disappear from the F 1 generation? Mendel allowed 7 kinds of F 1 hybrid plants to self-pollinate producing an F 2 generation See page 265

9 Law of Segregation when any individual produces gametes, the copies of a gene separate, so that each gamete receives only one copy. A gamete will receive one allele or the other Each F 1 plant produces two types of gametes Ex: Tt x Tt


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