Ncert plus two biology surendran aduthila

1. LINKAGE AND CROSSING OVER

3. Mendel's Law of Independent Assortment Allele pairs separate independently during the formation of gametes. This means that traits are transmitted to offspring independently of one another.

4. Dihybrid cross - phenotypes

7. Bateson and Punnett also studied peas: Flower Color: P = purple p = red Pollen seed shape: L = long l = round True Breeding lines: PPLL x ppll P PpLl F1 Phenotype Number Exp Ratio Exp Number Purple long 284 9 215 Purple round 21 3 71 Red long 21 3 71 Red round 55 1 24 What is going on???? Crosses produced a deviation from the predicted Mendelian independent assortment ratios.

9. Test cross F1 to double recessive: Parents PpLl X ppll Gametes PL pl Pl pL pl Expect 1:1:1:1 ratio of phenotypes Bateson and Punnett observed 7:1:1:7 Some gamete types more common that others…but why???

18. Recombination Process

19. Peter J. Russell, iGenetics : Copyright © Pearson Education, Inc., publishing as Benjamin Cummings. Mechanism of crossing-over

20. No Linkage: Independent Assortment

21. Linkage without Recombination

22. Linkage with Recombination

27. Single Crossovers: Non-crossover (Parental) and Crossover (Recombinant) Gametes What is the maximum % recombination?

30. Genetic Map of Drosophila melanogaster