Chapter 9 Cell Reproduction

1.Ratio of Surface Area to Volume Chapter 9 Cellular Reproduction What is the Surface area and volume of these cubes? What Limits Cell Size?

Cellular Reproduction  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 Cellular Growth

2. Transport of Substances  Substances move by diffusion or by motor proteins.  slow and inefficient. Cellular Reproduction Chapter 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. Cellular Reproduction Chapter Cellular Growth

The Cell Cycle  Cell division prevents the cell from becoming too large. Cellular Reproduction  Cells reproduce by a cycle of growing and dividing called the cell cycle. Chapter Cellular Growth

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

Mitosis

Prophase Chromatin (DNA) tightens and becomes visible Spindle fibers appear Centrioles migrate to the poles (opposite sides) Nuclear envelope disappears

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?

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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

Cellular Reproduction 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 Chapter Cell Cycle Regulation

Cell typeLife span Esophagus2-3 days can divide Small intestine1-2 days can divide Large intestine6 days can divide Red blood cells<120 days cannot divide White blood cells0 hrs – decades many do not divide Smooth muscleLong lived can divide Heart muscleLong lived cannot divide Nerve cellsLong lived most do not divide Stomach cells5 days Nerve cells in brainAs old as you are Liver1-1.5 years Adult skeleton7-10 years Outer layer of skin2 weeks

Cellular Reproduction 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 Chapter Cell Cycle Regulation

Cellular Reproduction Stem Cells- another way to produce new cells  Unspecialized cells that can develop into specialized cells when under the right conditions Chapter Cell Cycle Regulation

Cellular Reproduction 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 Cell Cycle Regulation

Cellular Reproduction 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 Chapter Cell Cycle Regulation