NATS 1610 Lecture Notes - Sister Chromatids, Semiconservative Replication, Meiosis
21 Jan 2014
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L20 forming the living body the basics. The living body begins at fertilization when one sperm fertilizes an egg: fertilization enables the combination of dna from 2 parents. Creating genetic diversity: the fertilized egg zygote cleaves to increase cell numbers. Human adults 10 to 65 to 100 trillion living cells. The metabolic requirements set an upper limit to the size of a single cell: as a cell increases in size its volume increases faster than its surface area (sa) Smaller objects have a greater ratio of surface area to volume: the sa of a cell is its cell membrane. Want to have more cell membrane (sa) for efficient nutrient waste diffusion. Cells divide instead of growing larger to limit their surface area to volume ratios: as cells gets larger, volume increases faster than sa (of cell membrane) Less surface area per unit volume, thus, less cell membrane for nutrient/waste diffusion: cells get around this problem by:
