Final answer:
The fertilized egg cell’s genetic material forms a genotype dictating the offspring's phenotype which includes physical traits, disease susceptibility, and more, influenced by both genetic and environmental factors. This leads to a unique individual, with gender determined by the sperm cell's chromosome and mitochondrial DNA passed from the mother.
Step-by-step explanation:
The moment a sperm cell and egg cell combine during fertilization, they form a zygote with a complete set of chromosomes. This single cell contains genetic material - DNA - from both parents, resulting in a unique combination that will not be identical to either parent. As the zygote develops, it undergoes numerous cell divisions, and the genes within these chromosomes guide the formation and specialization of cells to build a complex organism.
The genetic information involved is crucial as it determines not just physical traits like eye color, height, and hair color, but also susceptibility to certain diseases and, to some extent, personality traits and abilities. This genetic blueprint contained within the zygote’s DNA is called its genotype. However, while the genotype provides the potential for certain traits, the actual traits that manifest, known as the phenotype, are the result of both genetic and environmental influences.
This process also includes the exclusive transmission of mitochondrial DNA from the mother, as sperm contribute only their DNA and not cytoplasmic organelles. The gender of the offspring is determined by whether an X or Y chromosome is carried by the fertilizing sperm cell, with the egg cell having receptors for both types.