6-5 Traits and Probability Punnett squares – a grid system for predicting all possible genotypes resulting from a genetic cross A Aa a Pg 183

6-5 Traits and Probability Punnett squares – a grid system for predicting all possible genotypes resulting from a genetic cross A Aa a AA A A a a aa Monohybrid cross Examine inheritance of only 1 trait

6-5 Traits and Probability Testcross Why does this work? Cross between an organism with an unknown genotype and an organism with the recessive phenotype. The recessive phenotype has to be homozygous, meaning this parent will only pass along the recessive allele. If the offspring exhibit the recessive phenotype we know the “unknown” carried the recessive allele

6-5 Traits and Probability Testcross a A? a Aa A ? a a ? a

6-5 Traits and Probability Testcross a Aa a Aa A aa a a a Recessive phenotype

6-5 Traits and Probability Testcross a AA a Aa A Aa a A a NO Recessive phenotype

6-5 Traits and Probability Dihybrid crosses T(height) and R(color) Crosses that examine the inheritance of two different traits We are examining the inheritance of height and color, knowing that both T’s or R’s cannot be passed on TtRr Law of independent assortment

6-5 Traits and Probability Allele pairs separate independently of each other during gamete formation TtRr T T t t R Rrr These are the possible gametes produced by one parent

X ? ? ? ? TR tR Tr tr

XTRtRTrtr TR tR Tr tr

XTRtRTrtr TR TTRR tR Tr tr

XTRtRTrtr TR TTRRTtRRTTRrTtRr tR Tr tr

XTRtRTrtr TR TTRRTtRRTTRrTtRr tR TtRRttRRTtRrttRr Tr tr

XTRtRTrtr TR TTRRTtRRTTRrTtRr tR TtRRttRRTtRrttRr Tr TTRrTtRrTTrrTtrr tr

XTRtRTrtr TR TTRRTtRRTTRrTtRr tR TtRRttRRTtRrttRr Tr TTRrTtRrTTrrTtrr tr TtRrttRrTtrrttrr

XTRtRTrtr TR TTRRTtRRTTRrTtRr tR TtRRttRRTtRrttRr Tr TTRrTtRrTTrrTtrr tr TtRrttRrTtrrttrr

XRTRtrTrt RT RRTTRRTtRrTTRrTt RT RRTTRRTtRrTTRrTt rT RrTTRrTtrrTTrrTt rT RrTTRrTtrrTTrrTt

6-5 Traits and Probability Probability Number of occurrences Likelihood an event will happen Can be expressed as fractions, simplified fractions, or ratios TOTAL Number of possibilities