c Now let's consider diploid organisms haploid gametes diploid(2n) or (egg) meIosIS diploid zygote c△ somatic cells (sperm) meIOSIs erm cells The genotype of the zygote will depend on which alleles are carried in the gametes Allele sperm gamete A A/a Zygote a/A a/a When heterozygotes mate their offspring will have different phenotypes: If A is dom nant to a, the two possible phenotypes will be the phenotype of a/a or the phenotype of A/A and A/a When we do breeding experiments it is important to know the genotypes of the parents But as you can see from the example above individuals with the dominant trait could be either A/A or Wa. A method to control this type of variation is to start with populations that we know to be homozygous. One way to do this is to keep inbreeding individuals until all crosses among related individuals always produce identical offspring. This is known as a true-breeding population and all individuals can be assumed to be homozygousLecture 3 Now let’s consider diploid organisms: The genotype of the zygote will depend on which alleles are carried in the gametes. When heterozygotes mate their offspring will have different phenotypes: If A is domi￾nant to a, the two possible phenotypes will be the phenotype of a/a or the phenotype of A/A and A/a. When we do breeding experiments it is important to know the genotypes of the parents. But as you can see from the example above individuals with the dominant trait could be either A/A or A/a. A method to control this type of variation is to start with populations that we know to be homozygous. One way to do this is to keep inbreeding individuals until all crosses among related individuals always produce identical offspring. This is known as a true-breeding population and all individuals can be assumed to be homozygous. A/A A/a a/A a/a A a A a sperm egg Allele in gamete Zygote