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Cell Growth and Reproduction Slid e2 Growth and Reproduction of Cells Cell growth and reproduction of cells are the most fundamental of all living functions and together constitute the cell life cycle Cell growth—depends on using genetic information in DNA to make the structural and functional proteins needed for cell survival Cell reproduction —ensures that genetic information is passed from one generation to the next Slid e3 Growth and Reproduction of Cells Cell growth —a newly formed cell produces a variety of molecules and other structures necessary for growth using the information contained in the genes of DNA molecules; this stage is known as interphase Production of cytoplasm—more cell material is made, including growth and/or replication of organelles and plasma membrane; a largely anabolic process Slid e4 Growth and Reproduction of Cells Cell growth (cont.) DNA replication Replication of the genome prepares the cell for reproduction; mechanics are similar to RNA synthesis DNA replication DNA strand uncoils and strands come apart Along each separate strand, a complementary strand forms The two new strands are called chromatids, instead of chromosomes Chromatids are attached in pairs, and the centromere is the name of their point of attachment Slid e5 Growth and Reproduction of Cells Cell growth (cont.) Growth phase of the cell life cycle can be subdivided into the first growth phase (G1), the [DNA] synthesis phase (S), and the second growth phase (G2) Slid e6 Growth and Reproduction of Cells Cell reproduction—cells reproduce by splitting themselves into two smaller daughter cells (Table 4-5) Mitotic cell division—the process of organizing and distributing nuclear DNA during cell division has four distinct phases (Figure 4-31) Slid e7 Growth and Reproduction of Cells Mitotic cell division (cont.) Prophase—“before-phase” After the cell has prepared for reproduction during interphase, the nuclear envelope falls apart as the chromatids coil up to form chromosomes, which are joined at the centromere (Figure 4-30) As chromosomes are forming, the centriole pairs are seen to move toward the poles of the parent cell and spindle fibers are constructed between them Slid e8 Growth and Reproduction of Cells Mitotic cell division (cont.) Metaphase—“position-changing phase” Chromosomes move so that one chromatid of each chromosome faces its respective pole Each chromatid attaches to a spindle fiber Slid e9 Growth and Reproduction of Cells Mitotic cell division (cont.) Anaphase—“apart phase” Centromere of each chromosome has split to form two chromosomes, each consisting of a single DNA molecule Each chromosome is pulled toward the nearest pole, forming two separate but identical pools of genetic information Slid e 10 Growth and Reproduction of Cells Mitotic cell division (cont.) Telophase—“end phase” DNA returns to its original form and location within the cell After completion of telophase, each daughter cell begins interphase to develop into a mature cell