Cell Division A cell grows in size by increasing both the size and the number of its cells. Then 2...

Cell DivisionA cell grows in size by increasing both the

size and the number of its cells. Then 2 grow and divide, forming and so on.

Cell Cycle: The regular sequence of growth and division that cells undergo

Cell cycle is also known as the Mitosis cycle.

Asexual Reproduction – Mitosis The process in which the nucleus divides to

form two new nuclei

Three reasons why cells reproduce by asexual reproduction:

1. Growth 2. Repair 3. Replacement

Cells that reproduce by asexual reproduction reproduce constantly.

Mitosis Cycle

• Three stages:

1. Interphase

2. Mitosis• Prophase• Metaphase• Anaphase• Telophase

3. Cytokinesis

Interphase occurs before mitosis begins

• Interphase is considered to be the 'living' phase of the cell, in which the cell obtains nutrients, grows to full size, reads its DNA, and conducts other "normal" cell functions.

• Majority of the life of the cell

CELL MEMBRANENucleus

Cytoplasm

Interphase:considered to be the 'living' phase of the cell, in which the cell obtains nutrients,

grows, reads its DNA, and conducts other "normal" cell functions.

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Stage 2: MitosisMitosis begins – cells begin to divide

Scientists divide mitosis into 4 parts, or phases:1.Prophase2.Metaphase3.Anaphase4.Telophase

Phase 1 Prophase• Centrioles (or poles) appear and begin to move to

opposite end of the cell. • Spindle fibers form between the poles.• Nuclear envelope breaks down

CentriolesSister chromatids

Spindle fibers

Prophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Centrioles

Phase 2: Metaphase• Chromosomes attach to the spindle fibers at its centromere (center).

The Chromosomes line up across the center of cell.

Spindle fibers

Metaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Phase 3: AnaphaseThe chromosomes split in half.Each side of the newly split chromosome move to opposite ends of the cell.

Centrioles

Spindle fibers

Anaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Phase 4: Telephase• Two new nuclei form. • Chromosomes appear as chromatin (threads

rather than rods).• A new nuclear envelope forms around each region

of chromosomes.• Mitosis ends.

NucleiNuclei

Chromatin

Telophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Stage 3: Cytokinesisoccurs after mitosis

• Final stage of the cell or mitosis cycle.

• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Typical Cell cycle in an animal cell

Time to complete cycle?How long it takes

for a cell to go through mitosis depends on the cell. A human liver cell, for example, completes one cell cycle in about 22 hours.

Animal Mitosis -- Review

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Plant Mitosis -- ReviewInterphase

Prophase

Metaphase

Anaphase

Telophase

Interphase