Stages of Cell Division to Know for Anatomy and Physiology I

Cell division is essential for growth, repair, and maintaining healthy tissues. Understanding the stages—Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis—helps us grasp how cells replicate and ensure genetic stability, crucial in Anatomy and Physiology.

1. Interphase

   • The longest phase of the cell cycle, accounting for about 90% of the total time.
   • Divided into three sub-phases: G1 (cell growth), S (DNA synthesis), and G2 (preparation for mitosis).
   • During S phase, each chromosome is replicated, resulting in two sister chromatids.
   • The cell performs its normal functions and prepares for division by synthesizing proteins and organelles.
   • Critical for ensuring that the cell is ready for the subsequent stages of division.

2. Prophase

   • Chromatin condenses into visible chromosomes, each consisting of two sister chromatids.
   • The nuclear envelope begins to break down, allowing spindle fibers to access the chromosomes.
   • The mitotic spindle, made of microtubules, starts to form from the centrosomes.
   • Chromosomes begin to move toward the cell's equatorial plane.
   • Key stage for ensuring proper chromosome alignment and attachment to spindle fibers.

3. Metaphase

   • Chromosomes align along the metaphase plate (equatorial plane) of the cell.
   • Spindle fibers attach to the centromeres of the chromosomes at the kinetochores.
   • Ensures that each daughter cell will receive an identical set of chromosomes.
   • The cell checks for proper attachment of spindle fibers to prevent errors in chromosome separation.
   • Critical for maintaining genetic stability during cell division.

4. Anaphase

   • Sister chromatids are pulled apart and move toward opposite poles of the cell.
   • The centromeres split, allowing the chromatids to separate and become individual chromosomes.
   • The cell elongates as the spindle fibers shorten, facilitating the movement of chromosomes.
   • Ensures that each daughter cell will have the correct number of chromosomes.
   • A crucial phase for preventing aneuploidy (abnormal number of chromosomes).

5. Telophase

   • Chromosomes reach the poles and begin to de-condense back into chromatin.
   • The nuclear envelope re-forms around each set of chromosomes, creating two distinct nuclei.
   • The spindle apparatus disassembles, and the cell prepares for division.
   • Cytokinesis begins during this phase, leading to the physical separation of the cytoplasm.
   • Important for restoring the cell's normal structure and function post-division.

6. Cytokinesis

   • The final step of cell division, where the cytoplasm divides, resulting in two daughter cells.
   • In animal cells, a cleavage furrow forms, pinching the cell membrane to separate the cells.
   • In plant cells, a cell plate forms, leading to the development of a new cell wall.
   • Ensures that each daughter cell has its own organelles and sufficient resources to function.
   • Vital for completing the cell division process and maintaining tissue homeostasis.