Lecture 19-20, apoptosis for 2019F.pdf - Apoptosis In animal cells there are at least three forms of cell death Cultured cells In tissue Figure 18-1

Lecture 19-20, apoptosis for 2019F.pdf - Apoptosis In...

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Apoptosis
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Necrosis (A): cell death due to acute injury/insult, typically involves cell swelling and lysis Þ potential damaging inflammatory responses. Apoptosis (B and C): more controlled form of cell death that does not involve cell lysis. Instead, dead cell becomes engulfed and destroyed by phagocytosis in our body. Programmed necrosis (or necroptosis ): shares some components with apoptosis, but involves cell lysis (e.g., as defense against certain kinds of viral infection). In animal cells, there are at least three forms of cell death Cultured cells In tissue Figure 18-1 Molecular Biology of the Cell (© Garland Science 2015)
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Figure 18-2 Molecular Biology of the Cell (© Garland Science 2015) Apoptosis is important for embryonic development, cellular homeostasis in normal adult tissues (e.g., size of liver), elimination of damaged cells , and other processes Figure 18-3 Molecular Biology of the Cell (© Garland Science 2008) excessive apoptosis Þ various degenerative diseases, immunodeficiency, infertility, etc. Syndactyly insufficient apoptosis Þ cancer, autoimmunity, etc. Examples of human medical problems that result from: metamorphosis
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Apoptosis eliminates unwanted cells (e.g., those that fail to repair damaged DNA [or other cellular lesions] even after cell cycle arrest upon checkpoint activation) Figure 17-16 Molecular Biology of the Cell (© Garland Science 2015)
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Figure 20-13 Molecular Biology of the Cell (© Garland Science 2015) Both increased cell division (proliferation) and decreased apoptosis can contribute to tumorigenesis Cells in a tumor often have increased levels of cell division as well as decreased levels of apoptosis
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Alive Dead Apoptotic signals Survival signals Cells actively participate in the decision to live or die The balance of these signals dictate whether a cell lives or dies
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Apoptotic cells have many characteristic features
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Cytoskeleton collapses Cell shrinks and condenses (i.e., change in cell shape). Blebbing of plasma membrane and subsequent pinching off of apoptotic bodies Nuclear envelope disassembles Chromosomes condense and then become fragmented Phosphatidylserine (PS) appears on cell surface (instead of being only in the luminal leaflet of the plasma membrane).
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