1 / 26

Mendel and His Discoveries

Mendel and His Discoveries. Chapter 11. Gregor Mendel. Gregor Mendel (1822-1884) Experimented with pea plants and developed fundamental rules of genetics and patterns of inheritance. Punnett Squares. Crosses between parents that differ in only one trait are called MONOHYBRID CROSSES.

darcie
Download Presentation

Mendel and His Discoveries

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mendel and His Discoveries Chapter 11

  2. Gregor Mendel • Gregor Mendel (1822-1884) Experimented with pea plants and developed fundamental rules of genetics and patterns of inheritance.

  3. Punnett Squares • Crosses between parents that differ in only one trait are called MONOHYBRID CROSSES. • P= Parents • F1= First Filial generation (kids) • F2= Second Filial generation (grandkids)

  4. Mendel and Pea Plants • For his plant experiment he crossed a tall plant with a short plant. • All of the offspring looked tall. • Why? • Because the tall plants had a dominant trait and the short plants had a recessive trait.

  5. Alleles • Alleles are simply versions of genes THE ALLELES FOR COW FUR COLOR ARE BLACK. BROWN, AND WHITE

  6. Prediction of Genetic Crosses • The alleles for tallness of a plant: • TT= Dominant (Tall) • tt= Recessive (Short) • How do we know for sure that they would all be tall? • The Punnet Square

  7. Punnett Squares • Tool to predict outcomes of genetic crosses • Make a tic-tac-toe board • Place the parent alleles like below: TALL PARENT PLANT SHORT PARENT PLANT

  8. Let’s try another one… • If the trait is for feather color of parrots, then GG= Dominant and is green. • gg= recessive and is gold. • GG allele is homozygous dominant; (Homo- same; zygous-sex cell; dominant- dominant)

  9. gg allele is homozygous recessive; (Homo- same; zygous- sex cell; recessive- recessive) • So from the cross above we get all Gg. So are they Green or gold or a mix of both?

  10. They are all green. Gg is called heterozygous. Heterozygous means different. • If a G and a g are together to make a heterozygous trait, the trait looks like the dominant gene or G. So, ALL the parrots look green.

  11. But what about the KIDS of these new, green parrots? • Genetics of the new, GREEN (F1) parrots: • Gg x Gg

  12. Ratios? • Phenotype: the “look” of the genes • Genotype: the “letters” or alleles of the organism PHENOTYPE RATIOS: 3:1 GENOTYPE RATIOS: 1 GG, 2Gg 1gg

  13. Why we needed the math: The Dihybrid Cross • Lets say that in peas, We cross a Homozygous dominant Smooth, yellow seed with a Homozygous recessive wrinkled, green seed. What would be the genotype and phenotype of the F1 generation?

  14. Setting it up • SS= Smooth YY= yellow • ss= wrinkled yy= green • So we are crossing a SSYY x ssyy

  15. Ready, set, go! • Most important question: What are all of the possible sperm and egg that each plant can produce with those alleles? (huh?) SSYY Plant ssyy Plant sy SY

  16. The product of this cross will all be: • SsYy, or all Smooth, Yellow peas (F1) • But what about the F2 generation?

  17. Ask the Important Question again! • Most important question: What are all of the possible sperm and egg that each plant can produce with those alleles? SY Sy SsYy sY sy PEA SEED

  18. 9:3:3:1

  19. Incomplete Dominance • What do you get when you cross a homozygous dominant red rose with a homozygous white rose?

  20. Incomplete Dominance • A Pink Rose! • Since all of the F1 are Rr= pink, what would be the F2 generation of all of the F1 pink roses?

  21. 1 Red: 2 Pink: 1 White

  22. Codominance • Codominance- when both alleles contribute to the phenotype of the organism

  23. Multiple Alleles • When three or more alleles of the same gene exist in a population • i.e. blood types (A, B, O)

  24. Continuous Variation • - The range of small differences of a single trait in a population. • It is usually where several genes effect a single trait.

More Related