Mendelian Genetics How are traits passed from parents to offspring?

Mendel and his pea plants

Results of Mendel’s experiments each parent contributes one factor (gene) for a trait to their offspring Each parent contributes equally to the traits of offspring Some forms of genes (alleles) can mask other alleles Dominant allele Recessive allele

Dominant and recessive alleles

Representing dominant and recessive alleles Dominant alleles represented by capital letter For example: Stem height- dominant allele is tall (T) Recessive alleles represented by lowercase letter For example: Stem height- recessive allele is short (t)

Practice with dominant and recessive alleles Seed color in pea plants Yellow (Y) is dominant and Green (y) is recessive What color will the seeds of a pea plant with YY be? What color will the seeds of a pea plant with yy be? What color will the seeds of a pea plant with Yy be?

Genotypes and Phenotypes Genotype = the combination of alleles an organism has for a given trait Phenotype = the physical trait you actually see Genotypes Phenotypes

Practice with Genotypes and Phenotypes Pod shape in pea plants Smooth (S) is dominant, pinched (s) is recessive What phenotype will you see if the genotype of the pea plant is SS? What phenotype will you see if the genotype of the pea plant is Ss? What genotype(s) could result in a pinched pod shape? What genotype(s) could result in a smooth pod shape?

So how can the likelihood of traits being passed from parents to offspring be predicted? PUNNETT SQUARES!!