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Genetics

Genetics. The Puzzle of Heredity. What is Genetics?. Genetics is the scientific study of heredity. Who is Gregor Mendel?. Austrian Monk Experimented repeatedly with garden peas Kept careful records based on NUMBERS. Why peas?. Easy to grow Produce abundant offspring SELF-FERTILIZE

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Genetics

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  1. Genetics The Puzzle of Heredity

  2. What is Genetics? • Genetics is the scientific study of heredity.

  3. Who is Gregor Mendel? • Austrian Monk • Experimented repeatedly with garden peas • Kept careful records based on NUMBERS

  4. Why peas? • Easy to grow • Produce abundant offspring • SELF-FERTILIZE • CROSS-FERTILIZE

  5. Pea’s characteristics • Mendel studied 7 different pea characteristics. • We will look at flower color.

  6. The experiment • Mendel allowed peas to self-fertilize for several generations.

  7. The Experiment • The resulting offspring were true-breeding. • They produced only one form of a trait. Purple flowers produced purple flowers and white flowers produced white flowers.

  8. The Experiment • Mendel named these plants the P generation. • P stands for parental.

  9. The Experimental • Mendel then took pollen from a white flower plant and allowed it to fertilize a purple flower plant.

  10. The Experiment • He collected and grew the resulting seeds.

  11. The Experiment • All of resulting plants from these seeds produced only purple flowers. • Mendel named this the F1 generation. • F stands for filial.

  12. The Experiment • Mendel allowed the F1generation to self-fertilize. • He grew the seeds from these plants.

  13. The Experiment • In addition to white flowers, purple flowers appeared. • Mendel named this generation the F2generation.

  14. The Experiment • Mendel discovered the ratio of purple flowers to white flowers was 3:1.

  15. Conclusions • Parents transmit information about traits to their offspring. • Mendel called these factors.

  16. Conclusions • The purple factor is represented by a P. • Capital letter • The white factor is represented by a p. • Lower case letter

  17. Conclusions • Each individual has 2 factors for each trait. • One factor comes from each parent.

  18. Conclusions • Possible factor combinations for flower color are: • PP • Pp • pp

  19. Conclusions • Organisms possessing the same factors for a trait are homozygous. • PP • pp

  20. Conclusions • Organisms possessing different factors for a trait are heterozygous. • Pp

  21. Conclusions • Some factors are “stronger” than other factors. • These are called dominant factors.

  22. Conclusions • Dominant factors are represented by a capital letter. • The dominant factor is expressed. • It can be seen

  23. Conclusions • Some factors are weaker than others. • These are called recessive. • They are represented by a lower case letter.

  24. Conclusions • Purple flowers are dominant to white flowers. • White flowers are recessive.

  25. Conclusions • The phenotype refers to an organism’s appearance.

  26. Conclusions • The genotype is all of the factors or genes an organism possesses.

  27. Conclusions • Today we know Mendel’s factors were actually genes.

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