4 Phases of the Cell Cycle 1 G

4 Phases of the Cell Cycle : 1. G 1 (gap 1) - stage = Interphase 2. S phase - stage = Interphase 3. G 2 (gap 2) - stage = Interphase 4. M phase - stages = Mitosis & Cytokinesis

Cell Cycle – Interphase, Mitosis, & Cytokinesis

Mitosis is divided into 4 phases : 1. Prophase – 1 st phase (longest) 2. Metaphase – 2 nd phase 3. Anaphase – 3 rd phase 4. Telophase – 4 th (final) phase (think PMAT to recall order)

Prophase (first) 1. Prophase – the 1 st and longest phase of mitosis during which the : A. Chromosomes condense & become visible. B. Centrioles move to opposite sides of the nucleus. C. Nucleolus disappears. D. Nuclear membrane breaks down. E. Spindle (fanlike structure that helps separate chromosomes) forms. F. Spindle fibers attach to centromeres of chromosomes.

Metaphase 2. Metaphase – 2 nd phase of mitosis during which the chromosomes line up across the center of the cell. (M&M : Meta = middle)

Anaphase 3. Anaphase – 3 rd phase of mitosis during which the centromeres split & individual chromatids move toward the poles. (AAA – in ANAPHASE chromosomes are pulled APART & move AWAY to opposite sides).

Telophase (opposite of Prophase happens) 4. Telophase – 4 th & final phase of mitosis during which the : A. Chromosomes uncoil into a mass of material & can’t be seen. B. Nuclear membrane re-forms around each cluster of chromosomes. C. Spindles break apart. D. Nucleolus becomes visible in each daughter cell. *Cytokinesis usually occurs at the same time as Telophase.

Cytokinesis – division of cytoplasm. -In animal cells cytokinesis occurs by drawing in the cytoplasm until it pinches into 2 parts (cleavage furrow). -In plant cells cytokinesis occurs when a structure known as the cell plate forms midway between the divided nuclei. The cell plate becomes a separating membrane & the cell wall forms in it.

Plant Cell Mitosis