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1 Mendelelian Genetics. 2 Gregor Johann Mendel Austrian monk Austrian monk Studied the inheritance of traits in pea plants Studied the inheritance of.

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Presentation on theme: "1 Mendelelian Genetics. 2 Gregor Johann Mendel Austrian monk Austrian monk Studied the inheritance of traits in pea plants Studied the inheritance of."— Presentation transcript:

1 1 Mendelelian Genetics

2 2 Gregor Johann Mendel Austrian monk Austrian monk Studied the inheritance of traits in pea plants Studied the inheritance of traits in pea plants Developed the laws of inheritance Developed the laws of inheritance Called the Father of Genetics" Called the Father of Genetics"

3 3 Mendels Experimental Methods Mendel hand-pollinated flowers using a paintbrush He could snip the stamens to prevent self-pollination Covered each flower with a cloth bag He traced traits through the several generations

4 4 Reproduction in Flowering Plants Pollen contains sperm; Produced by the stamen Ovary contains eggs; Found inside the flower Pollen carries sperm to the eggs for fertilization Self-fertilization can occur in the same flower Cross-fertilization can occur between flowers

5 5 Why Give Peas A Chance?? Can be grown in a small area Can be grown in a small area Produce lots of offspring Produce lots of offspring Produce pure plants when allowed to self-pollinate several generations Produce pure plants when allowed to self-pollinate several generations Can be artificially cross-pollinated Can be artificially cross-pollinated

6 6 Mendels First Experiments

7 7 Genetic Terminology Trait - any characteristic that can be passed from parent to offspring Trait - any characteristic that can be passed from parent to offspring Heredity - passing of traits from parent to offspring Heredity - passing of traits from parent to offspring Genetics - study of heredity Genetics - study of heredity

8 8 Genetic Terminology Alleles - two forms of a gene (dominant & recessive) Alleles - two forms of a gene (dominant & recessive) Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R) Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R) Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r) Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r)

9 9 More Terminology Genotype - gene combination for a trait (e.g. RR, Rr, rr) Genotype - gene combination for a trait (e.g. RR, Rr, rr) Phenotype - the physical feature; what you SEE; resulting from a genotype (e.g. red, white) Phenotype - the physical feature; what you SEE; resulting from a genotype (e.g. red, white)

10 10 Genotype & Phenotype in Flowers Genotype of alleles: R = red flower r = yellow flower All genes occur in pairs, so 2 alleles affect a characteristic Possible combinations are: GenotypesRR Rrrr PhenotypesRED RED YELLOW

11 11 Types of Genetic Crosses Monohybrid cross - cross involving a single trait e.g. flower color Monohybrid cross - cross involving a single trait e.g. flower color Dihybrid cross - cross involving two traits e.g. flower color & plant height Dihybrid cross - cross involving two traits e.g. flower color & plant height

12 12

13 13 Trait: Seed Shape Alleles: R – Roundr – Wrinkled Cross: Round seeds x Wrinkled seeds RR x rr P 1 Monohybrid Cross R R rr Rr Genotype:Rr Genotype: Rr PhenotypeRound Phenotype: Round Genotypic Ratio:100% Rr Genotypic Ratio: 100% Rr Phenotypic Ratio: 100% Round


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