Study GuideBiology–Mitosis and Cell Reproduction1. The Cell Cycle: How Cells Grow and DivideLiving cells are constantly growing, working, and reproducing. Most cells in the body repeat thispattern over and over in a process called thecell cycle. With a few exceptions—such as red bloodcells, which do not have a nucleus—almost all cells go through this cycle.The cell cycle hastwo main stages:1.Interphase–when the cell grows and carries out its normal functions2.Mitosis–when the cell divides to form two new cells1.1 Interphase: The Cell’s Busy LifeInterphase is the longest part of the cell cycle. During this time, the cell is not resting—it is very active.Interphase is divided intothree phases: G1, S, and G2.1.1.1 G1 Phase: Growth and Normal WorkTheG1 phasehappens right after mitosis. During this phase, the cell grows and produces theproteins and enzymes it needs to do its specific job.For example:•Apancreas cellproduces insulin•Amuscle cellcontracts to allow movement•Asalivary gland cellproduces digestive enzymesAt this stage, each chromosome is made ofone DNA moleculewrapped around histone proteins.•Normal human body cells have46 chromosomes•Sex cells have23 chromosomes•Red blood cells haveno chromosomesbecause they lack a nucleusPreview Mode
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