Chapter 10-2

Chromosomes are not visible in cells until cells begin the process of cell division. Chromosomes are not visible in cells until cells begin the process of cell division.

Chromosomes consist of two identical sister chromatids. Chromosomes consist of two identical sister chromatids.

A centromere holds the two sister chromatids together at their centers. A centromere holds the two sister chromatids together at their centers.

Cell Cycle Cell Cycle The cell goes through a stage called interphase between cell divisions. The cell goes through a stage called interphase between cell divisions.

Cells grow and then divide in a series of events called the cell cycle. Cells grow and then divide in a series of events called the cell cycle.

M phase is the when the nucleus divides. M phase is the when the nucleus divides.

Interphase consists of: Interphase consists of: G 1 phase G 1 phase S phase S phase G 2 phase G 2 phase

G 1 phase - cells do most of their growing. G 1 phase - cells do most of their growing.

S phase S phase

G 2 phase G 2 phase

Mitosis Four phases: Four phases: –Prophase –Metaphase –Anaphase –Telophase

Mitosis Centrioles are the tiny structures located in the cytoplasm near the nuclear envelope at the beginning of prophase. Centrioles are the tiny structures located in the cytoplasm near the nuclear envelope at the beginning of prophase.

Mitosis Spindle – is the fanlike microtuble structure that helps separate the chromosomes. Spindle – is the fanlike microtuble structure that helps separate the chromosomes.

Mitosis During Prophase: During Prophase: the chromosomes become visible in the nucleus; the chromosomes become visible in the nucleus; the centrioles take up positions on opposite sides of the nucleus. the centrioles take up positions on opposite sides of the nucleus.

Mitosis During Metaphase: During Metaphase: The chromosomes line up in the center of the cell. The chromosomes line up in the center of the cell.

Mitosis During Anaphase : During Anaphase : The chromosomes move until they form two separate The chromosomes move until they form two separate Forming groups at opposite poles of the spindle. Forming groups at opposite poles of the spindle.

Mitosis During Telophase: During Telophase: the nuclear envelope re-forms around each cluster of chromosomes; the nuclear envelope re-forms around each cluster of chromosomes; the nucleolus becomes visible in each daughter nucleus. the nucleolus becomes visible in each daughter nucleus.

Cytokinesis Cytokinesis is the division of the cytoplasm. Cytokinesis is the division of the cytoplasm.

Cytokinesis How does it happen in animals? How does it happen in animals? The membrane is drawn downward until it is pinched into nearly two equal parts. The membrane is drawn downward until it is pinched into nearly two equal parts.

Cytokinesis A cell plate is formed midway between the divided nucleus during cytokinesis in plant cells. A cell plate is formed midway between the divided nucleus during cytokinesis in plant cells.