Biology- Mitosis and Cell division

The primary purposes of mitosis are growth, repair, and replacement of cells, In a typical 24-hour eukaryotic cell cycle (such as in human somatic cells), mitosis and cytokinesis combined (the M phase) occupy a very short period, usually lasting only about 1 hour. The majority of the cell's time (roughly 23 hours or 95% of the cycle) is spent in interphase preparing for division.

Interphase

A cell spends 90% of its time, during the cell is busy taking in nutrients, replicating DNA and growing.

There are 3 stages: G1,S,G2

G1 stage

Cell grows and produces new proteins and organelles.

10-11 hours

S stage

DNA is replicated.

8 hours

G2 stage

Cell produces the organelles and structures needed for cell division.

3-4 hours

Chromatin

Relaxed/Uncoiled

Chromosome

Condensed and replicate form

Sister Chromatids

Replicated chromosomes consist of two of these.

Prophase

Chromatin condenses to become chromosomes (2 sister chromatids)

Nuclear envelope disintegrates

Mitotic spindle/spindle fibers form

Centrioles move to opposite poles of the cell

Metaphase

Chromosomes move to the middle of the cell

Miotic spindles attach to the centromeres of the chromosome

Anaphase

Sister chromatids separate at the centromere

Pulled to opposite poles by the centriole

Telophase

Miotic spindle breaks down

Two new nuclei are formed

Cell splits into two new daughter cells by pinching inwards

Cytoplasm divides= Cytokinesis

Cytokinesis

The actual splitting of the cytoplasm into two separate cells

Occurs differently in both plant and animal cells

Animal cells: Cleavage furrow pinches cell

Plant cellls: Cell plate forms in between

Two Daughter Cells: The primary outcome is two separate cells, each enclosed by its own plasma membrane.