1 st law (segregation) based on the observation that characteristics disappear and reappear in peas
Two members of a gene pair segregate from each other during the formation of gametes such that half the gametes carry one member and the other half carry the other member
Offspring from parental genotypes of R/r X R/r receive one of the two alleles from each parent.
The “dominant allele” R determines the phenotype
The ratio of dominant (R) to recessive (r) phenotypes would be 3:1
Mendelian Genetics R / r X R / r S/S S/s s/S s/s ¼ ½ ¼ S/s X S/s R / R R / r r / R r / r R/R = ¼ R/r = ½ r/r = ¼ The probability that an offspring will have a certain genotype is predictable knowing parental genotypes Segregation occurs here in Meiosis I in both parents Meiosis I II