Alleles for a particular type of gene are simply represented by a letter A assigned a capital letter, for example, G, while the recessive one is represented using a small letter, for example, G. In the example above, G could represent the dominant allele for pointed nose and g represent the recessive allele for rounded nose. The boy is said to be heterozygous for nose shape because he carries two different types of alleles(GG). The boy's father is homozygous for nose shape because he has only one type of allele(gg).The boy's mother could either be homozygous(GG) or heterozygous(Gg) and we will find out why this is the case when we investigate the Mendel's experiments.