Lecture13_Apoptosis

Lecture13_Apoptosis - Programmed cell death (apoptosis)...

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Programmed cell death ( apoptosis ) Apoptosis - a regulated form of cell death: why? Cytology of apoptosis. Differences between apoptosis and necrosis. Functions for apoptosis in development and homeostasis. Common disease states are associated with an imbalance in apoptosis. Apoptosis can be initiated by signals from inside or outside the cell. Growth factors and cell adhesion promote cell survival via suppression of apoptosis. 1 Bio 103-Fall 2009 © Steven Gross
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Apoptosis - a regulated form of cell death massive turnover of cells within the human body is normal. Each hour, millions of normal cells die within the gut and bone marrow. These cells are replaced by new cells via mitosis from small populations of stem cells. Controlled cell death plays critical role in balancing overall number of cells, both during embryonic development and in post-natal life. Apoptosis: a normal process of controlled cell death that occurs during development or in homeostasis of organs. Apoptosis and programmed cell death synonymous; often used interchangeably. Apoptosis of inter-digital cells during vertebrate limb development Apoptosis of tadpole tail during metamorphosis 2 Bio 103-Fall 2009 © Steven Gross
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Apoptosis Vs Necrosis Apoptosis Chromatin condensation DNA laddering Cell shrinkage Cellular fragmentation No cellular rupturing No inflammatory response Engulfment of dead cells Typically affects single cells Necrosis No chromatin condensation No DNA laddering Cellular rupture Inflammatory response Typically affects groups of cells Necrosis: cell death due to acute insult, trauma, infection cells swell and burst, releasing contents. This elicits an inflammatory response. Apoptosis : cell surface is altered so recognized by macrophages—avoids uncontrolled cell lysis & damaging inflammatory response; cells eaten/digested quickly by neighboring cells/macrophages, avoids most damage to tissue 3 Bio 103-Fall 2009 © Steven Gross
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Functions of apoptosis 4 1 & 2. Sculpting tissue 3. Regulate cell number: Ex.: In dev. Nervous sys., ~1/2 all nerve cells die 4. Quality control: eliminate abnormal, misplaced nonfunctional or damaged cells. Ex: elim T- and B- lymphocytes that produce self-reactive receptors; elim. Many excess lymphocytes after infection; elim. virus-infected cell before virus can replicate; elim. cancerous cells 5. Very high rate of apoptosis in bone marrow, e.g. of neutrophils (which fight infection) short lived, but have large supply of young ones ready to fight infection Bio 103-Fall 2009 © Steven Gross
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Many human diseases are associated with an imbalance in apoptosis Disorders associated with inhibition of apoptosis Follicular lymphoma Breast cancer Prostate cancer Ovarian cancer Lupus Viral infections (e.g. adeno, herpes, pox) Disorders associated with excessive apoptosis AIDS Alzheimer’s Parkinson’s ALS Aplastic anemia Alcoholism
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This note was uploaded on 12/13/2011 for the course BIOSCI d103 taught by Professor Staff during the Fall '11 term at UC Irvine.

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Lecture13_Apoptosis - Programmed cell death (apoptosis)...

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