Chapter 4

• Interphase, also known as the “resting period”, is when the cell grows, develops, functions, and copies DNA.
• S Phase, or DNA synthesis and replication, is when the cell replicates its DNA.
• G1 Phase is a period of rapid cell growth and activity.
• G2 Phase is when the cell prepares to divide.
• Mitosis is the phase where the cell divides for reproduction with zygote and fertilization or divides because of cytokinesis in order to multiply and start over.
• Prophase is the phase where the cells chromatin condenses into chromosomes which contain DNA, and all material in prophase has a copy, the two chromosome arms are called “sister chromatids” joined by centromeres.
• During prophase, the nuclear membrane dissolves and the nucleolus disappears.
• Spindle fibers begin to form from centrosomes which work to pull apart cell matter in later phases.
• Metaphase is the phase where the spindle fibers guide cell matter to the equator located in the middle of the cell.
• All sister chromatids are still attached at this time during metaphase.
• Anaphase is the phase where each centromere splits apart and is pulled by spindle fibers to separate the sister chromatids into single chromosomes.
• The chromatids are pulled to opposite poles during anaphase.
• Telophase is the phase where chromosomes have reached opposite poles and unwind less visible chromatin, spindle fibers break down and the nuclear membrane reappears, and a nucleolus forms in each new nucleus.