How do punnett squares exemplify the law of segregation?
Punnett Squares illustrate the separation of alleles for genes.
Mom and Dad's two alleles will separate at meiosis (one allele for one type of sperm or one type of egg). This is because mom and dad's sperm and eggs have half the normal chromosomal number, or a haploid number, compared to most body cells.
Why? Two haploid (one set of chromosomes) cells will combine in fertilization. To make what? To make the new baby, or zygote. This is the diploid cell.
It now has two sets (one set of chromosomes from mom, one set from dad) of chromosomes. This means the cell is 'diploid'.
The 4 squares within a simple Punnett Square represent the chances of offspring having a certain genotype.
Once again: they represent the percentage (out of 4, since there are four squares) of a particular genotype in an offspring.
To be clear, these genotypes DO NOT mean that four children will be born.