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5.1 The Cell Cycle SPONGE 1 Why do you think that you always have to cut your hair, your fingernails, and the lawn? The growth is made by new cells being made. 5.1 The Cell Cycle KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. 5.1 The Cell Cycle Cycles 5.1 The Cell Cycle Your body cells go through a cycle too. This cycle allows new cells to be created to heal or replace dead or damaged cells. 5.1 The Cell Cycle • The cell cycle is a regular pattern of growth, DNA replication, and cell division that occurs in eukaryotic cells. • The cell cycle is the process of duplicating somatic or body cells 5.1 The Cell Cycle STAGE 1- Gap 1 (G1) •Cells carry out their normal functions •Cells increase in size •Organelles increase in number * Cells spend most of their time here 5.1 The Cell Cycle STAGE 2- Synthesis (S) •Cell makes a copy of its nuclear DNA •By the end of S stage the cell contains 2 complete sets of DNA 5.1 The Cell Cycle STAGE 3- Gap (G2) •Cells continue to carry out their normal functions •Additional growth occurs 5.1 The Cell Cycle STAGE 4 (includes 2 processes) •Mitosis •The division of a body cell’s nucleus and its contents •2 new nuclei form •Cytokinesis •The process that divides the cell cytoplasm * 5.1 The Cell Cycle 5.1 The Cell Cycle The result of the cell cycle is 2 daughter cells that are identical to the original cell 5.1 The Cell Cycle Cells divide at different rates. • The rate of cell division varies with the need for those types of cells. • Some cells are unlikely to divide (G0). 5.1 The Cell Cycle Cell size is limited. • Volume increases faster than surface area. 5.1 The Cell Cycle • Surface area must allow for adequate exchange of materials. – Cell growth is coordinated with division. – Cells that must be large have unique shapes.