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Mendel’s Principle of Dominance or Recessiveness

Mendel’s Principle of Dominance or Recessiveness. Traits found in humans. Engage. Map of X and Y Chromosomes. Explore 1. Fundamentally Genetics You and your groups will be looking at each other to determine whether you are dominant or recessive for the following traits.

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Mendel’s Principle of Dominance or Recessiveness

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  1. Mendel’s Principle of Dominance or Recessiveness Traits found in humans

  2. Engage • Map of X and Y Chromosomes

  3. Explore 1 • Fundamentally Genetics • You and your groups will be looking at each other to determine whether you are dominant or recessive for the following traits.

  4. Tongue Rolling

  5. Earlobes

  6. Earbump • Often called Darwin’s Ear Bump • Dominant - Having a small bump on the ear • Recessive - Not having the bump

  7. Widow’s Peak

  8. Hitchhiker’s Thumb

  9. Polydactyly

  10. Syndactyly Feet

  11. Syndactyly Hands

  12. Severe Syndactyly

  13. Syndactyly Surgery

  14. Cleft Chin

  15. Clockwise Hair Whorl

  16. Autosomal Dominant and Recessive • Huntington Disease – Dominant Disease • Cystic Fibrosis – Recessive Disease Sickle Cell Anemia Tay-Sach’s PKU

  17. Explore 2 • Bugs, Bugs, Bugs • Genes for traits are encoded and arranged linearly on structures called chromosomes found in the nuclei of most cells. When organisms reproduce, the resulting offspring should receive an equal number of chromosomes from the mother and the father. • In this activity you use the chromosomes and Bug Traits Key to determine the genotype and phenotype of the offspring.

  18. Exploration 3 • Wisconsin Fast Plant Genetics Lab

  19. Explore 4 • Punnett Squares • You will be able to predict the outcomes of crosses by completing this next activity.

  20. Explain • Mendel & The Gene Idea

  21. Mendel and Genetics • Answer the following questions as we explain the concepts surrounding basic genetic

  22. It All Began with Mendel (FYI) • Gregor Mendel was born in 1822. • Called the “Father of Genetics” • Late 1800 chromosomes and the process of meiosis were unknown. • Mendel’s work was considered obscure and unimportant until 1900 • Walter Sutton proposed the Chromosome Theory and people began to listen to his ideas. • Chromosome Theory – specific genes are located on specific chromosomes

  23. Three Conclusions to His Research • Principle of Dominance and Recessiveness One allele in a pair may mask the effect of the other • Principle of Segregation The two alleles for a characteristic separate during the formation of eggs and sperm • Principle of Independent Assortment The alleles for different characteristics are distributed to reproductive cells independently.

  24. Mendelian genetics • Character (heritable feature, i.e., fur color) • Trait (variant for a character, i.e., brown) • True-bred (all offspring of same variety) • Hybridization (crossing of 2 different true-breds) • P generation (parents) • F1 generation (first filial generation)

  25. Genetic vocabulary……. • Punnett square: • Gene: point on a chromosome that controls the trait • Allele: an alternate form of a gene A or a • Homozygous: identical alleles for a character • Heterozygous: different alleles for a gene • Phenotype: physical traits • Genotype: genetic makeup • Testcross: breeding of a recessive homozygote X dominate phenotype (but unknown genotype)

  26. How can the Chances of an Offspring’s Traits be Determined? • BY USING A PUNNETT SQUARE • Get out your Punnett Squares Problems • In groups of two come to the board and complete the given monohybrid problems.

  27. Bb X BbPhenotypic Ratio3:1Genotypic Ratio1:2:1 B b B B B B b b B b b b

  28. Exploration 4 • What about two traits? • Complete the second half of your Punnett Square Problems

  29. What about 2 Traits? • BbTt x BbTt • The Gametes contain one of each of the alleles. (BT). • Each of the offspring contain four alleles exactly like the parents.(BbTt). • Notice the number of possible offspring has increased. • The phenotypic ratio is 9:3:3:1

  30. BbTt x BbTt

  31. Exceptions to Mendel’s Rule

  32. Incomplete Dominance • The phenotype of the heterozygote is intermediate between those of the two homozygotes. • Ex) Snap Dragon Color • Red, Pink, White

  33. Co-dominance • Phenotype of both homozygotes are produced in heterozygotes individuals. • Both alleles are expressed equally. • Ex)Roan Cattle White-feathered birds are both homozygotes for both B and W alleles

  34. Multiple Alleles • Ex )Blood type • Blood type A and B are co-dominant, while O is recessive. • Forms possible blood types of A, B, AB, and O.

  35. Blood Also Shows Codominance

  36. Sex-Determination • Chromosome pairs 1-22 are autosomes • Chromosome pair 23 are sex chromosomes • They determine the sex of an individual • XX = female XY = male

  37. Sex-Linked Inheritance • Traits that are only found on the X chromosome • Colorblindness and Hemophilia are examples of sex-linked traits. • These genes are recessive and found only on the X chromosome.

  38. Polygenic Inheritance • Inheritance pattern of a trait that is controlled by two or more genes. • Gene may be on the same chromosome or on different chromosomes. • Ex) Skin color and Height

  39. ELABORATION 1Exceptions to the Rule Punnet Squares: Dihybrid, Sex-Linked, Multiple Alleles, Co-Dominance, Incomplete Dominance

  40. Elaboration 2 • Who’s the Parents? • Upon completion of this lab, you will: • determine the ABO blood types of two sets of parents and two newborn children • examine the genetic relationships possible between the parents and children • match the “mixed up” children with their proper parents.

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