lecture 24 - Lecture24...

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Lecture 24 apoptosis is cell death, a specific type of cell death necrotic cells result in the cells blowing up and lysing All multicellular organisms can undergo apoptosis. The idea is that you can protect the whole organism at the sacrifice of a certain number of cell. single celled organism do not undergo apoptosis Factors are required to keep cells alive cells that are deprived of growth factors will commit apoptosis, if there growth factors are removed. Programmed cell death is a developmental process that usually proceeds by apoptos- is apoptosis is also the mode of cll death occurring in a variety of the other settings It has roles in: normal homeostasis inhibition of cancer disease process The cell has two different types of protein product that protect it from cancer: tumor suppressors - stop cell division promote apoptosis To result in cancer it usually takes 7 to 8 genetic mutations in the same cell to have unregulated growth, because of all of the natural mechanisms that the cell have within them. Apoptosis is miss regulate, if you either have defects in the pathway for apoptosis so you don’t allow apoptosis you produce diseases. if you have too much apoptosis then cells that should live don’t and you end up nemrodegenerative disease It cell has its own balance of positive and negative regulators of apoptosis, so that when they are exposed to prevent genetic changes that result in tumorigenic or treated with chemotherapy, what the cell does in response to that depends on the natural set point of the positive and negative regulators. Apoptosis is found in all multicellular organisms including plants but it is not found in bacteria or single celled eukaryotic organisms. It is often referred to as genetically programmed cell suicide. Multicellular organisms sacrifice some cells to save the entire organism. It makes no sense to have single celled organisms to commit suicide. Normal development process that require apoptosis 1. Eliminate 50% of neurons during development 2. Elimination of cells between fingers and toes 3. Turning off the proliferation of the immune cells after exposure to an immunogen 4. The generation of immunotolerance to an organisms own antigens 5. Elimination of 131 out of 1090 adult cells of nematodes. There are two different pathways for apoptosis: those that are triggered from ligands that are external to the cell
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those that are intrinsic due to processes that occur within the cell Abnormal processes that require apoptosis 1. Elimination of cells that have been damaged by UV, heat stress, cold stress, in- fection by viruses 1. all of these induce apoptosis 2. Elimination of cancer cells 1. either they lack tumor suppressor genes, players in apoptosis, or DNA repair pathways so that the chances of mutating increases. If apoptosis is defective, it may cause autoimmune diseases or cancer. Too much ap-
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This note was uploaded on 01/26/2009 for the course BIOLOGY 244 taught by Professor Palter during the Fall '05 term at Temple.

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lecture 24 - Lecture24...

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