5.1 The Cell Cycle KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. 5.1 The Cell Cycle 5.1 The Cell Cycle More prefixes• Stage-step or part of mere-segment or part • Phase-appearance Soma-body • Divide-to separate Centro-center • Duplicate-an identical copy • Double-to increase twofold Condense-reduce volume • Copy-reproduction from an original • Kine-movement • inter-between • pro-before • meta-middle • Ana-back • telo-end Cells double their DNA in order to divide and create two nearly identical duplicates or copies.” 5.1 The Cell Cycle A. Interphase-cell growth • Gap1 (G1)-rapid protein synthesis, lots of enzyme activity, organelles replicate (copy) • Synthesis (S)-chromosomes become visible, replicate and are now called sister chromatids connected by the centromeres. • Gap 2 (G2)-more metabolic activity, centrioles duplicate and form spindle fibers made of microtubules. 5.1 The Cell Cycle • The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis. – 1.Gap 1 (G1):2. cell growth and normal functions – 3.DNA synthesis (S): 4.copies DNA – 5.Gap 2 (G2): 6.additional growth 8. cell/nuclear division – 7. Mitotic Phase: includes division of the cell nucleus (mitosis) and division of the cell cytoplasm 13.cytokinesis 14. Mitosis 15. Cell cycle 5.1 The Cell Cycle Cells divide at different rates • G1-varies the greatest • G0 – this cell is unlikely to divide again 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 • If cell is too small the cell does not contain all the organelles it needs. • If a cell is too large-needed nutrients could not diffuse in and waste could not diffuse out. (starve or poison itself) 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.