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Dihybrid Crosses

Dihybrid Crosses. Crosses that involve two characters Use a 16 box Punnet square Write the genotype for one trait, then write the genotype for the second- Rryy or rrYY or RRYy etc etc .

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Dihybrid Crosses

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  1. Dihybrid Crosses Crosses that involve two characters Use a 16 box Punnetsquare Write the genotype for one trait, then write the genotype for the second- Rryy or rrYY or RRYyetc etc. Make sure to pick the order of traits and stick with it! You don’t want to mix RrYYwith yyRr

  2. Setting up the Punnet Square • Lets say parent one is FfRr FfRr= FR, Fr FR, Fr, fR, fr FfRr= fR, fr

  3. Setting up the Punnet Square • Lets say parent two is ffRR ffRR= fR, fR fR, fR, fR, fR ffRR = fR, fR

  4. Setting up the Punnet Square • Now, add in the genotypes of the parents to your Punnet Square: FR Fr fR fr fR fR fR fR

  5. Setting up the Punnet Square • Now Cross! FR Fr fR fr fR fR fR fR FfRR FfRr ffRR ffRr FfRR FfRr ffRR ffRr FfRR FfRr ffRR ffRr FfRR FfRr ffRR ffRr

  6. Practice Two guinea pigs met and fell in love. The female was homozygous for black hair (BB) and homozygous for short hair (hh). The male was heterozygous for black hair (Bb) and heterozygous for long hair (Hh). What is the genotype of the mom? What is the genotype of the dad? What are you going to use to set up your Punnetsquare? BBhh BbHh Bh, Bh, Bh, Bh and BH, Bh, bH, bh

  7. Bh Bh Bh Bh BH Bh bH bh BBHh BBHh BBHh BBHh BBhh BBhh BBhh BBhh BbHh BbHh BbHh BbHh Bbhh Bbhh Bbhh Bbhh How many had long black hair? Long brown hair? Short brown hair? Short black hair? 8 0 Must equal 16 0 8

  8. TR Tr tR tr TR TTRR TTRr TtRR TtRr (always 4 possibilities) TR TTRr TtRR TtRr TTRR Tall & Red Tall & White Short & Red Short & White 12 4 0 0 Tr TtRr Ttrr TTRr TTrr 12 : 4 : 0 : 0 Tr TTRr TTrr Ttrr TtRr

  9. EeLl EeLl EL El eL el EL EELL EELl EeLL EeLl El EEll EeLl Eell EELl Free hanging & Large Free hanging & Small Attached & Large Attached & Small 9 3 3 1 eL eeLL eeLl EeLL EeLl 9 : 3 : 3 : 1 el EeLl Eell eell eeLl

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