Mendelian GeneticsHow 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 allelesDominant alleleRecessive 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

GenotypesPhenotypes

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!!