Heredity: transmission of traits from one generation to the next. Genetics: scientific study of heredity and inherited variation. Mitosis two cells identical to father/mother. Genes: inherited by both parents and account for family resemblances. Genes program cells to synthesize enzymes and proteins. Gametes: reproductive cells transmit genes from one generation to the next. During fertilization male and female gametes unite passing genes to offspring. Dna of eukaryotic cell is packaged into chromosomes within nucleus. Humans have 46 chromosomes in somatic cells. Locus: genes specific location along length of chromosome. Organisms that reproduce asexually have offspring with exact genetic copies of themselves. Asexual reproduction: single individual is the parent and passes copies of all genes to offspring without fusion of gametes. Sexual reproduction: unique combinations of genes inherited from both parents. Vary genetically from their siblings and both parents. Fertilization and meiosis alternate in sexual life cycles. Humans each somatic cell has 46 chromosomes.