The Cell Cycle and Mitosis

Cell Cycle

• Interphase• Mitosis• Cytokinesis

IMPORTANCE

• 1. Growth• 2. Tissue Repair• Means of asexual reproduction for

single celled eukaryotes.• 3. Keeps chromosome number

constant.

Eukaryotic Cell Cycle

• 1. Most of cell cycle consists of the interphase

• 2. Mitosis describes nuclear division

INTERPHASE

• 1. Cell prepares for mitosis

• 2. Chromosomes duplicate.• (Chromosomes consist of two DNA

strands).

Eukaryotic Cell Cycle

• Most of cell cycle consists of the interphase.

• Mitosis describes nuclear division.

STAGES OF MITOSIS

• 1. Prophase

• 2. Metaphase

• 3. Anaphase

• 4. Telophase

PROPHASE

• 1. Chromosomes coil up and become visible

• 2. Nuclear membrane disappears.

• 3. Nucleolus disappears.

• 4. Spindle appears.

• 5. Centrioles move toward poles

What’s a spindle?

• Made of the centriole and microtubules (part of the cytoskeleton)

• The fibers attach to the centromere of the chromosome and “reel them in”

• Interpretive Dance Time

METAPHASE

Chromosomes become aligned at the equator of the spindle.

ANAPHASE

• 1. Chromatids separate.

• 2. Two identical groups formed.

• 3. Separated chromatids move to opposite poles of the cell.

TELOPHASE

• 1. Chromosomes uncoil and disappear

• 2. Nuclear membrane reappears.

• 3. In plant cells the cell plate appears.

• Spindle fibers dissolve

Daughter Cell

• The cytoplasm becomes divided (a process called cytokinesis) and wall formation produces two daughter cells.

CRITICAL THINKING

• Human red blood cells develop in the bone marrow from stem cells, and lose their nucleus before maturing and being released into the bloodstream. While this gives a cell that can be densely packed with hemoglobin molecules, what are the consequences as for as the longevity & its ability to replicate?

CRITICAL THINKING

• Lacking DNA coding,the red blood cells will not themselves

• be able to replicate• and we must rely on the stem cells in

the bone marrow to continue red blood cell production. In addition, the red blood cells will be limited in life span and unable to make substantial DNA-coded repairs.