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

MitosisStage 2: Metaphase

•Chromosomes attach to spindle fibers

•Chromosomes line up along the equator of the spindle

•Very short phase

MitosisStage 3: Anaphase

•Begins as sister chromatids separate

•Centromeres split apart

•Chromatids are pulled to opposite poles of the cell

MitosisStage 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!!!