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Incomplete Dominance Codominance. In a nutshell!. PP = purple. Pp = purple. pp = white. Review: Dominant/Recessive. One allele is dominant over the other (capable of masking the recessive allele). PP. Pp. Pp. pp. Review Problem: Dominant/Recessive.
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Incomplete DominanceCodominance In a nutshell!
PP = purple Pp = purple pp = white Review: Dominant/Recessive • One allele is dominant over the other (capable of masking the recessive allele)
PP Pp Pp pp Review Problem: Dominant/Recessive • In pea plants, purple flowers (P) are dominant over white flowers (p) show the cross between two heterozygous plants. P p GENOTYPES: - PP (1); Pp (2); pp (1) - ratio 1:2:1 P p PHENOTYPES: - purple (3); white (1) - ratio 3:1
Snapdragons HUH? http://www.dobermann-review.com/info/genetics/mendels_genetic_laws/Gregor%20Mendel.jpg http://faculty.pnc.edu/pwilkin/incompdominance.jpg
Incomplete Dominance R1 F1 X R2 F2 http://www.google.ca/images?hl=en&q=incoplete%20dominance&rlz=1W1SNNT_enCA397&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1345&bih=555 R2R2 does not produce pigment Heterozygote only produces ½ pigment of R1R1
http://2.bp.blogspot.com/_uPFMFfHgGGg/SygBEtl5D1I/AAAAAAAAAKc/nylZiiL2k7s/s320/incomplete+dominance.jpghttp://2.bp.blogspot.com/_uPFMFfHgGGg/SygBEtl5D1I/AAAAAAAAAKc/nylZiiL2k7s/s320/incomplete+dominance.jpg
RR = red rr = white Rr = pink Incomplete Dominance • A third (new) phenotype appears in the heterozygous condition. • Neither trait is completely dominant over the other, so a heterozygous plant is a mix.
R r r r Rr Rr rr rr Problem: Incomplete Dominance • Show the cross between a pink and a white flower. GENOTYPES: - Rr (2); rr (2) - ratio 1:1 PHENOTYPES: - pink (2); white (2) - ratio 1:1
Codominance • The heterozygous condition, both alleles are expressed equally • Lots of times, fur color in animals is this way. (think spotted or 2 colors)
CODOMINANCE • The condition in which both alleles in a heterozygous organism are expressed. (Both are dominant together) • BOTH alleles contribute to the phenotype. • The two alleles don’t blend, but are rather both present in the offspring.
Roan Horse http://search.vadlo.com/b/q?rel=2&keys=Dominance+Incomplete+Dominance+Codominance+PPT
Roan Cattle http://www.ccs.k12.in.us/chsteachers/BYost/Biology%20Notes/CH11notescoincompletedom_files/image004.jpg Variegated Clover http://3.bp.blogspot.com/_zUPrgMM5tUg/SSVdrs59_uI/AAAAAAAAAA8/qJGjG2nZPhk/s200/codominance.GIF