Genes have a specific DNA sequence of about 220 nucleotides that have a specific location on each. In metaphase of mitosis nucleoli and nuclear envelope begin to break up. In prophase of meiosis, homologous chromosomes come together and lie side by side. The non-specialized cells from which spermatogenesis begins are spermatozoa.
Alleles are always dominant.
A tool used by geneticists to help predict the results of crosses is the genetic square. According to the Principle of Independent Assortment, during gamete formation, pairs of alleles segregate independently of one another. A, B, and AB only A only B only A and B only A, B, and O only 13. For fertilization to occur, a sperm must penetrate an egg. Cleavages that completely divides the egg are said to be diploblastic.