Transcript Chapter 9
Chapter 9 Cell Reproduction Chapter 9 Cellular Reproduction What Limits Cell Size? 1. Ratio of Surface Area to Volume What is the Surface area and volume of these cubes? Chapter 9 Cellular Reproduction 9.1 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. Chapter 9 Cellular Reproduction 9.1 Cellular Growth 2. Transport of Substances Substances move by diffusion or by motor proteins. slow and inefficient. Chapter 9 Cellular Reproduction 9.1 Cellular Growth 3. 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. Chapter 9 Cellular Reproduction 9.1 Cellular Growth The Cell Cycle Cell division prevents the cell from becoming too large. Cells reproduce by a cycle of growing and dividing called the cell cycle. Interphase G1 (Growth) The cell is growing, carrying out normal cell functions, and preparing to replicate DNA by checking for damage S (Synthesis) The cell copies its DNA in preparation for cell division. G2 The cell prepares for the division of its nucleus. Cell organelles are replicated Cell cycle animation Mitosis Chromatin (DNA) tightens and becomes visible Spindle fibers appear Centrioles migrate to the poles (opposite sides) Nuclear envelope disappears Prophase Metaphase Chromosomes line up in the middle of cell Anaphase Chromosome split and move to opposite ends of the cell Telophase Spindle fibers disappear Nuclear membrane reappears Cytokinesis In animal cells, microfilaments constrict, or pinch, the cytoplasm. In plant cells, a new structure, called a cell plate, forms. What is the result at the end of mitosis? Are the cells different or the same? What is this important? http://www.cellsalive.com /mitosis.htm http://www.stolaf.edu/people/giannini/flashanimat/celldivision/crome3.swf Objectives Explain how cancer relates to the cell cycle Describe the role of apoptosis Summarize the types of stem cells Cell Cycle Regulation Normally a combination of enzymes and proteins regulate the cell cycle Controlling stages of the cell cycle Monitoring for errors Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Apoptosis Programmed cell death Cells going through apoptosis actually shrink and shrivel in a controlled process. Gets rid of cells that are damages Used during embryotic development Cell type Life span Esophagus 2-3 days can divide Small intestine 1-2 days can divide Large intestine 6 days can divide Red blood cells <120 days cannot divide White blood cells 0 hrs – decades Smooth muscle Long lived can divide Heart muscle Long lived cannot divide Nerve cells Long lived Stomach cells 5 days Nerve cells in brain As old as you are Liver 1-1.5 years Adult skeleton 7-10 years Outer layer of skin 2 weeks many do not divide most do not divide What happens when cell division does not go correctly? Cancer Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Causes of Cancer mutations Various environmental factors Physical agents sun Asbestos Tobacco Radiation Chemicals (benzene, vinyl chloride) Viruses? Influences that affect the ability to get cancer?? hereditary Diet and exercise Cell cycle and cancer Cancer animation Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Stem Cells- another way to produce new cells Unspecialized cells that can develop into specialized cells when under the right conditions Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Embryonic Stem Cells After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. These cells have not become specialized. Chapter 9 Cellular Reproduction 9.3 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