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Title: In a dihybrid cross involving CcSs and CcSs (both heterozygous for two traits) what is the genotypic ratio? Post by: oakrueangsit on May 30, 2012 C-curly antennae
c-straight antennae S-spotted wings s-no spots on wings Could you tell me the difference between the genotypic and phenotypic ratios for a dihybrid cross if the first question is too much? thanks Title: In a dihybrid cross involving CcSs and CcSs (both heterozygous for two traits) what is the genotypic ratio? Post by: 601078493 on May 30, 2012 Genotype means what the actual genetic composition is (so, ccSS or CcSs or CCss, etc) - phenotypic ratio is talking about what the APPEARANCE is - so CCss (curly non spotted) would be phenotypically the same as Ccss and CCSS (curly spotted) would be phenotypically the same as CcSs, CCSs, CcSS, etc.
This cross should give you a phenotype ratio of 9:2:2:1 with 9 curly spotted, 2 straight spotted, 2 curly non spotted and 1 straight non spotted. The genotypes would be more varied - you can get those by setting up a punnett square. Not doing that for you :p **EDIT: Sorry; messed up my math at first - note corrected ratio. And as a result set up the punnett square to double check so here are your genotypes: ---------CS--------Cs-------cS-------cs CS | CCSS | CCSs | CcSS | CcSs Cs | CCSs | CCss | CCSs | Ccss cS | CcSS | CcSs | ccSS | ccSs cs | CcSs | Ccss | ccSs | ccss So: CCSS: 1 CcSs: 3 ccSs: 2 ccSS: 2 Ccss: 2 CcSS: 2 CCSs: 3 ccss: 1 Title: In a dihybrid cross involving CcSs and CcSs (both heterozygous for two traits) what is the genotypic ratio? Post by: oakaniru on May 30, 2012 The genotypic ratio of this cross would be:
1 - CCSS 2 - CCSs 2 - CcSS 4 - CcSs 1 - CCss 2 - Ccss 1 - ccSS 2 - ccSs 1 - ccss |