DNA DNA is a double stranded molecule, with two strands wound around each other in a double helix formation. Codon Table Genotype versus Phenotype Genotype is the physical sequence or sequences at a locus. Phenotype is the physical expression of the genotype. Sperm and unfertilized eggs are haploid. Most of the Y chromosome is considered haploid.
Somatic cells are diploid in humans.
One from the father and one from the mother. Linkage requires minimally that the two loci be on the same chromosome. Genotype More than one gene may affect a trait. This is called a polygenic trait. When one gene affects multiple traits, we call this pleiotropy .