Mitosis and The Cell Cycle

Mitosis

Part of eukaryotic cell division during which the cell nucleus divides.

Cell Cycle

Series of events in which a cell grows, prepares for division, and divides to form two daughter cells.

Phases of Interphase

G1, S, G2.

G1 Phase

Stage of interphase in which the cell grows and performs its normal functions.

S Phase

The synthesis phase of the cell cycle; DNA is replicated.

G2 Phase

Stage of interphase in which the cell duplicates its cytosol and organelles, preparing for cell division.

Why does DNA replicate?

To maintain the same amount of DNA in each daughter cell after mitosis.

Phases of Mitosis

Prophase, Metaphase, Anaphase, Telophase.

Prophase

Chromosomes become visible, nuclear membrane/nucleolus dissolves, spindle and centrioles form.

Metaphase

The chromosomes line up across the equator of the cell.

Anaphase

The sister chromatids separate and move to opposite ends of the cell.

Telophase

The chromatids/chromosomes uncoil, and the nuclear membrane and nucleolus reform.

Cytokinesis

Division of the cytoplasm.

Order of Cell Cycle Phases

Interphase (G1, S, G2), Mitosis (Prophase, Metaphase, Anaphase, Telophase), Cytokinesis.

Cancer

Any malignant growth or tumor caused by abnormal and uncontrolled cell division.

Cytokinesis in Plant Cells

Cell plate forms.

Cytokinesis in Animal Cells

Cleavage furrow constricts to separate the cells.

Why do cells divide?

Growth, repair, healing, to make more cells.

What happens if a cell doesn't divide?

1. Slower communication (DNA overload), 2. inability to move waste and nutrients efficiently, 3. Slower diffusion.

Surface Area to Volume Ratio

Decreases when the cell becomes too large.

What regulates the cell cycle?

Cyclin-dependent kinase.

Programmed cell death

Apoptosis.

Why do some cells undergo apoptosis?

To stop cancerous cells from dividing and to rid a mutation.

What happens if cytokinesis occurs before mitosis?

Daughter cells would lack nuclei.

What happens if mitosis occurs without cytokinesis?

Cells would have multiple nuclei.

How do prokaryotic cells divide?

Binary fission.

Structure of a Chromosome

Consists of two sister chromatids and a centromere.

Number of Chromosomes in a Human Skin Cell

46 (23 pairs).