1. Cellular Reproduction

3.  As the cell grows, its volume increases much more rapidly than the surface area.  The cell might have difficulty supplying nutrients and expelling enough waste products.

4.  Substances move by diffusion or by motor proteins.  Diffusion over large distances is slow and inefficient.  Small cells maintain more efficient transport systems.

5.  Cell division prevents the cell from becoming too large.  It also is the way the cell reproduces so that you grow and heal certain injuries.  Cells reproduce by a cycle of growing and dividing called the cell cycle.

6.  Interphase is the stage during which the cell grows, carries out cellular functions, and replicates.  Mitosis is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide.  Cytokinesis is the method by which a cell’s cytoplasm divides, creating a new cell.

7.  The first stage of interphase, G 1  The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

8.  The cell copies its DNA in preparation for cell division.

9.  The cell prepares for the division of its nucleus.

10.  Prophase  The cell’s chromatin tightens.  Sister chromatids are attached at the centromere.  Spindle fibers form in the cytoplasm.

11.  The nuclear envelope seems to disappear.  Spindle fibers attach to the sister chromatids.

12.  Sister chromatids are pulled along the spindle apparatus toward the center of the cell.  They line up in the middle of the cell.

13.  The microtubules of the spindle apparatus begin to shorten.  The sister chromatids separate.  The chromosomes move toward the poles of the cell.

14.  The chromosomes arrive at the poles and begin to relax.  Two new nuclear membranes begin to form and the nucleoli reappear.  The spindle apparatus disassembles.

15.  In animal cells, microfilaments constrict, or pinch, the cytoplasm.  In plant cells, a new structure, called a cell plate, forms.  http://www.youtube.com/watch?v=JcZQk mooyPk http://www.youtube.com/watch?v=JcZQk mooyPk

16.  Different cyclin/CDK combinations signal other activities, including DNA replication, protein synthesis, and nuclear division throughout the cell cycle.

17.  The cell cycle has built-in checkpoints that monitor the cycle and can stop it if something goes wrong.  Spindle checkpoints also have been identified in mitosis.

18.  Cancer is the uncontrolled growth and division of cells.  Cancer cells can kill an organism by crowding out normal cells, resulting in the loss of tissue function.

19.  The changes that occur in the regulation of cell growth and division of cancer cells are due to mutations.  Various environmental factors can affect the occurrence of cancer cells.

20.  Programmed cell death  Cells going through apoptosis actually shrink and shrivel in a controlled process.

21.  Unspecialized cells that can develop into specialized cells when under the right conditions

22.  After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. These cells have not become specialized.

23.  Found in various tissues in the body and might be used to maintain and repair the same kind of tissue  Less controversial because the adult stem cells can be obtained with the consent of their donor