University:
California State University, Northridge
Course:
BIOL 380 | Cell Biology
Academic year:

2022
Views:

407

Pages:

4
Author:

folclord7m

Human life cycle, cell division processes and cycles, mitotic cell division, and cancer fi Cell division results in cell proliferation (i.e., increase in number) which may be bene cial or harmful. Human Life Cycle Requires mitotic/meiotic divisions • Human ≈ 1012 human cells (many more bacterial, protist, and fungal cells) • Somatic cells (2n) —body cells that divide mitotically (repair, growth, etc.) • Germ cells (2n) in gonads ultimately divide meiotically to form gametes (n) • Gametes (n) fuse during syngamy (aka fertilization) to form zygote (2n) • Zygote (2n) divides mitotically to form somatic/germ cells in offspring Genetic load (ploidy) Diploidy (2n) —two sets; 2n=46 Haploidy (n) —one set; n=23 Human Life Cycle Requires mitotic/meiotic divisions • Two forms of cell division in human life cycle: • Mitosis —proliferates genetic clones • Germ cells (2n) ➟ more germ cells (2n) • Zygote (2n) ➟ adult (2n) • Meiosis —reduces genetic load producing genetically unique cells • Germ cells (2n) ➟ gametes (n) • Genetically unique gametes (n) combine during syngamy (fertilization) ➟ zygote (2n) (combination of two sets of chromosomes from two different cells ↑ genetic diversity)