Mitosis: Cells at Work!!

What is Mitosis? Part of the cell cycle Nuclear cell division during which chromosomes are equally distributed to the 2 identical daughter cells that are formed Results in growth Continuous process 4 stages

What is the cell cycle? Continuous sequence of growth and division of a cell. 2 parts: Interphase & Mitosis Busiest and longest section is INTERPHASE

Phases of Interphase G1 phase – Growth and Protein Synthesis S phase – DNA Replication G2 phase – Checkpoint to make sure cell is ready to undergo mitosis

Mitosis Stage 1: Prophase Chromatin coils up into chromosomes Nucleus begins to disappear Centrioles migrate to opposite ends of cells and spindle forms

What is a chromosome? The condensed form of the original DNA connected to its identical copy Sister Chromatids

Mitosis Stage 2: Metaphase Chromosomes attach to spindle fibers Chromosomes line up along the equator of the spindle Very short phase

Mitosis Stage 3: Anaphase Begins as sister chromatids separate Centromeres split apart Chromatids are pulled to opposite poles of the cell

Mitosis Stage 4: Telophase Begins as chromatids reach the poles Chromosomes unwind and spindle breaks down New nuclei form around each set of chromosomes Plasma membrane separates

Cytokinesis: Division of the cytoplasm Animal cell Plasma membrane pinches along equator Forms a cleavage furrow that deepens until the cell is pinched in two Plant cell Plasma membrane does not pinch in b/c of rigid cell wall Cell plate forms at the equator that divides the cytoplasm

Cytokinesis: Division of the cytoplasm

I Pour Milk And Tea I—Interphase “The Xerox phase” P—Prophase “Cell PREPARES and chromosomes become visible” M—Metaphase “The chromosomes line up in the MIDDLE” A—Anaphase “The chromosomes pull APART” T—Telophase “The TWO identical daughter cells separate”

Purpose of Mitosis (Cell Division) AFTER mitosis, the 2 new daughter cells will be identical. Each new cell receives the correct number of chromosomes for that organism (Humans = 46 chromosomes) 23 from mom, 23 from dad When both sets of chromosomes are in a cell, it is said to be diploid. All somatic (body) cells are diploid.

Applications of Cell Division Regeneration of tissue after transplantation Regeneration of body parts (ex. Starfish) Spinal cord injuries Specialized cells for transplantation Embryo Development Ensures that the new cells will make the same proteins as the old cell!!!