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Bell Ringer: (5 min.)

Bell Ringer: (5 min.). Section 11-3: Exploring Mendelian Genetics. Independent Assortment. Mendel wanted to know: Does the segregation of one pair of alleles affect that of another? For example: Does the allele for seed color effect the shape of the seed?

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Bell Ringer: (5 min.)

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  1. Bell Ringer: (5 min.)

  2. Section 11-3: Exploring Mendelian Genetics

  3. Independent Assortment • Mendel wanted to know: • Does the segregation of one pair of alleles affect that of another? • For example: Does the allele for seed color effect the shape of the seed? • 1. To find this Mendel created a two factor cross and followed two different genes as they passed from one generation to the next.

  4. The Two Factor Cross: F1 • Crossed true breeding plants for round (RR) yellow (YY)peas • 2. Genotype (RRYY) • With true breeding plants for wrinkled (rr) green (yy) peas • 2. Genotype (rryy) • And proceeded to observe the offspring

  5. The Two Factor Cross: F1

  6. The F1 Results: • 3. This shows that the dominant alleles are present: • Phenotype: • Heterozygous • Round Yellow Seeds • Genotype: • RrYy • 4. Does this result show if genes segregate independently? • Nope

  7. The Two Factor Cross: F2 • 5. Mendel took the F1 generation (heterozygous) and crossed them. • He wanted to see if the two traits would separate independently of one another or if dominant would stick with dominant and recessive stay with recessive. • Was very curious of the possible outcomes.

  8. 10. The Two Factor Cross: F2

  9. The F2 Results: • 6. & 8. There was a total of 556 seeds produced: • Round Yellow: 315 • Round Green: 105 • Wrinkled Yellow: 104 • Wrinkled Green: 32 • 7. There were seeds that displayed combinations not found in the parents (RRYY and rryy) • Did Independent assortment occur? • YES!

  10. Let’s Look at the Numbers Again: • 9.Count up the Phenotypes, what is the ratio? • 9:3:3:1 • Round Yellow: 9 • RRYY, RrYy • Round Green: 3 • RRyy, Rryy • Wrinkled Yellow: 3 • rrYY, rrYy • Wrinkled Green: 1 • rryy

  11. 11. Independent Assortment • The alleles for a given trait segregate independently of one another and do not influence each other’s inheritance.

  12. 12. A Summary of Mendel’s Principles • The inheritance of biological characteristics is determined by genes that are passed down from parents to their offspring • 13. Two or more forms of a trait may exist (ex: Dominant and Recessive) • The copies of genes are segregated from each other when gametes are formed • The alleles for different genes usually segregate independently from one another

  13. Beyond Dominant and Recessive • 14. There are some alleles that are neither dominant or recessive, and many traits: • Genetics tends to be a bit more complicated than that: • The majority of genes have more than two alleles, and important traits are controlled by many different genes.

  14. 15. Incomplete Dominance • Cases in which one allele is not dominant over the other • The heterozygous phenotype is somewhere between the two homozygous phenotypes • Ex: • Strawberry Blonde • 4 ‘o Clock Plants

  15. 15. Codominance • Both alleles contribute to the phenotype • Both alleles will be shown in the offspring • Ex: • Erminette Animals • Black feathers is codominant with white • Offspring show both colors • Humans • Proteins synthesis

  16. 15. MultipeAlleles • Genes that have more than two possible alleles • This does not mean that an individual can have more than two alleles for a gene • It means that there could be more than two possibilities in a population • Ex: • Rabbit fur color • Blood Types in humans

  17. Multiple Alleles

  18. 15. Polygenic Traits • Traits that are controlled by two or more genes • Many traits are produced by the interaction of several genes • Ex: • Human Skin Color • 4 genes control skin color • Human Eye Color

  19. Applying Mendel’s Principles • Thomas Morgan- Geneticist that worked with Fruit Flies to test Mendel’s Principles of Segregation • 16. Chose Fruit Flies because: • Small in size • Easy to take care of in a lab setting • Capable of producing large numbers of offspring very quickly • 17. The conclusion: • Mendel’s Principles apply to not just pea plants, but other organisms as well

  20. Genetics and the Environment • 18. Genes are not the only factor for determining characteristics of an organism • The Environment plays a role as well • Ex: Sunflower Height is determined by the genes, but this will change depending on factors such as climate, water availability, and soil composition

  21. Exit Slip Katy Perry Wolverine X Hair Color: -B: Black -b: Blue Claws: -C: No Claws -c: Claws bbCc Bbcc

  22. Solve the Cross: Bbcc bbCc

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