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Corn Investigation

Corn Investigation. Count the number of kernels that are: yellow & smooth, yellow & wrinkled , purple & smooth, purple & wrinkled. Reduce this ratio to lowest terms (it is okay to have decimals in your answer) What type of inheritance are you examining? (Monohybrid or Dihybrid )?

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Corn Investigation

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  1. Corn Investigation • Count the number of kernels that are: yellow & smooth, yellow & wrinkled, purple & smooth, purple & wrinkled. Reduce this ratio to lowest terms (it is okay to have decimals in your answer) • What type of inheritance are you examining? (Monohybrid or Dihybrid)? • Based on the ratio from Q1, what could the possible genotypes of the parents be? (hint: do not do a punnett square. Look at the ratio to help you figure out the parents) • You are modelling how Mendel recorded data. Is counting an effective way to collect data? Why? What is one experimental error that could have occurred? (Hint: counting wrong is not an error)

  2. Beyond Mendelian Genetics

  3. Beyond Mendel • Mendelian Genetics deals with inheritance patterns that show complete dominance • Meaning, the dominant allele completely masks (overpowers) the expression of the recessive allele • Are inheritance patterns in nature always this simple?

  4. Incomplete Dominance • A situation where neither of the 2 alleles are dominant over the other. • Phenotype of heterozygote is a BLEND of the two alleles. • Alleles are written using a superscript letter (ex. CR = Red) • Example: snapdragons (see picture)

  5. Codominance • Both alleles are dominant, and thus fully expressed in the heterozygote • Exhibited in a heterozygousindividual where both alleles of a gene are expressed, not blended. Sickle Cell Anemia (blood disease) Cow coat Impatien flowers

  6. Examples of Co-Dominance Talk to me when there’s meat… meeow! Examples: • black cat x tan cat = Tabbycat (black and tan stripes) • Roan coat in horses (white and red hair)

  7. Multiple Alleles • So far, the inheritance examples we have looked at only have 2 alleles • Example: Brown hair or blonde hair, brown eyes or blue eyes, etc. • Most traits in nature are controlled by more than 2 alleles, such as human blood groups

  8. Multiple Alleles Recall:

  9. Multiple Alleles Recall:

  10. Multiple Alleles Recall:

  11. Multiple Alleles

  12. Multiple Alleles • When more than 3 phenotypes are possible, then more than 2 alleles for that trait must exist in the population. • However, individuals have only two of those alleles. Why? • Because only one allele is inherited from each parent

  13. Example of Multiple Alleles • The ABO system of human blood type involves three alleles (IA, IB, and i). • IA and IB – co-dominant, where “i” is recessive • As a result, there are four possible phenotypes or blood types: A, B, AB, and O.

  14. What do the Alleles Code For? • The blood types differ due to the molecules that are present on the outside of the red blood cells (antigens) • Antigens act as recognition factors for our immune system

  15. Type A Type AB Type B Type O What do the Alleles Code For? Both A & B No antigens

  16. What do the Alleles Code For? • When white blood cells do not recognize the antigen, it considers the cell an invader and produces antibodies to attack that cell • This is why receiving an incorrect blood type will cause agglutination (clumping).

  17. Human Blood Groups: Multiple Alleles AND Codominance • Human blood types are controlled by a single gene (expressed as an antigen: protein on surface of red blood cell)

  18. Example • If a man has type AB blood and his wife has type A blood (heterozygous), what are the possible blood types of their children?

  19. Summary Table

  20. Summary Table

  21. Summary Table

  22. Summary Table

  23. Summary Table

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