Unformatted text preview: Once mitosis is completed and interphase begins, the cell begins a period of growth. Growth begins during the first phase, called G 1 (gap), and continues through the S (synthesis) and G 2 phases. Also during the S phase the second DNA molecule for each chromosome is synthesized. As a result of this DNA replication, each chromosome gains a second chromatid. During the G 2 period of growth, materials for the next mitotic division are prepared. The time span from one cell division through G 1 , S, and G 2 is called a cell cycle (Figure 1). A cell that begins mitosis in the diploid state—that is, with two copies of every chromosome—will end mitosis with two copies of every chromosome. However, each of these chromosomes will consist of only one chromatid, or one DNA molecule. During interphase, the second DNA molecule is replicated from the first, so that when the next mitotic division begins, each chromosome will again...
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- Spring '10
- homologous chromosomes, nonsister chromatids. Chiasmata