In these cells (except egg and sperm cell) they"re 2 copies of each gene, one from each parent: alternative forms of a gene that produce different characteristics are called. Dominant, recessive and polygenic effects: genotypes and phenotypes are not identical some = dominant, some = recessive. Dna-methylation a process (mechanism) in which a gene will be. Turned off which prevents it from acting: other processes can alter a gene so that the gene product is changed. The human genome: the human genome project was started in 1990, and it was completed and published in. 25,000 fun fact: same amount as a fruit fly!: they found that 200 of our genes may have arisen from genes that bacteria inserted into out early ancestors. It is important to note that knocking out a single gene may disrupt a wide range of functions.