Cellular Reproduction

Transcription

1 Section 1: Cellular Growth Section 2: Mitosis and Cytokinesis Section 3: Cell Cycle Regulation Click on a lesson name to select.

2 Section 1 Cellular Growth Ratio of Surface Area to Volume

3 Section 1 Cellular Growth 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 Section 1 Cellular Growth Transport of Substances Substances move by diffusion or by motor proteins. Diffusion over large distances is slow and inefficient. Small cells maintain more efficient transport systems.

5 Section 1 Cellular Growth Cellular Communications The need for signaling proteins to move throughout the cell also limits cell size. Cell size affects the ability of the cell to communicate instructions for cellular functions.

6 Section 1 Cellular Growth The Cell Cycle 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.

7 Section 1 Cellular Growth 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.

8 Section 1 Cellular Growth The Stages of Interphase The first stage of interphase, G 1 The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

9 Section 1 Cellular Growth The Second Stage of Interphase, S The cell copies its DNA in preparation for cell division.

10 Section 1 Cellular Growth The Third Stage of Interphase, G 2 The cell prepares for the division of its nucleus.

11 Section 2 Mitosis and Cytokinesis The Stages of Mitosis Prophase The cell s chromatin tightens. Sister chromatids are attached at the centromere. Spindle fibers form in the cytoplasm.

12 Section 2 Mitosis and Cytokinesis The nuclear envelope seems to disappear. Spindle fibers attach to the sister chromatids.

13 Prophase

14 Section 2 Mitosis and Cytokinesis Metaphase Sister chromatids are pulled along the spindle apparatus toward the center of the cell. They line up in the middle of the cell.

15 Metaphase

16 Section 2 Mitosis and Cytokinesis Anaphase The microtubules of the spindle apparatus begin to shorten. The sister chromatids separate. The chromosomes move toward the poles of the cell.

17 Anaphase

18 Section 2 Mitosis and Cytokinesis Telophase 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.

19 Telophase

20 Section 2 Mitosis and Cytokinesis Cytokinesis In animal cells, microfilaments constrict, or pinch, the cytoplasm. In plant cells, a new structure, called a cell plate, forms.

21 Cytokinesis

22 Section 3 Cell Cycle Regulation Normal Cell Cycle Different cyclin/cdk combinations signal other activities, including DNA replication, protein synthesis, and nuclear division throughout the cell cycle.

23 Section 3 Cell Cycle Regulation Quality Control Checkpoints 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.

24 Section 3 Cell Cycle Regulation Abnormal Cell Cycle: Cancer 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.

25 Section 3 Cell Cycle Regulation Causes of Cancer 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.

26 Section 3 Cell Cycle Regulation Apoptosis Programmed cell death Cells going through apoptosis actually shrink and shrivel in a controlled process.

27 Section 3 Cell Cycle Regulation Stem Cells Unspecialized cells that can develop into specialized cells when under the right conditions

28 Section 3 Cell Cycle Regulation Embryonic Stem Cells After fertilization, the resulting mass of cells divides repeatedly until there are about cells. These cells have not become specialized.

29 Section 3 Cell Cycle Regulation Adult Stem Cells 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