KINE 1000 Lecture Notes - Lecture 1: Endonuclease, Fas Ligand, Cell Nucleus
4 Jun 2018
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Chapter 18- Cell Death
• Growth, development & maintenance of multicellular organisms depend on production
of cells & mechanisms to destroy them
• Reuies that ells die at sae ate as they’e podued
• Cells die he they eoe daaged o ifeted, esuig they’e eoed efoe
they’e theate the health of ogais
• Programed sequence of molecular events destroys cell itself & then eaten by other cells-
- Called programmed cell death occurs by process called apoptosis
• Cells die by apoptosis undergo morphological changes. They shrink & condense,
cytoskeleton collapses & nuclear envelope disassembles & nuclear chromatin condenses
& breaks into fragments
• Cell or apoptotic bodies become chemically altered so neighbooring cells or macrophage
rapidly englufs them before they spill contents. Prevents damaging inflammatory
response
• Cells that die in response to acute trauma or lack of blood supply by process called – cell
necrosis . Necrotic cells swell & burst spilling content over neighbors & results in
inflammatory response. Could also be caused by energy depletion- leads to metabolic
defects & loss in ionic gradients.
- Neoptosis is fo of pogaed ells death that’s tiggeed y speifi egulatoy
signals from other cells
Apoptosis Depeds o Itaellula Poteolyti Casade that’s Mediated y Caspases
• Apoptosis is triggered by specialized intracellular proteases which cleaves specific
sequences in proteins bringing dramatic changes & leads to cell death & engulfment
• Proteases have cysteine at active site & cleave their target proteins at specific aspartic
acids
- These proteins are called caspases
• Caspases are inactive & only active during apoptosis
• Two Major Classes of Apoptotic Caspases:
o Initiator caspases
o Executioner caspases
• Initiator Caspases
- Being apoptotic processes
- Exist as inactive, soluable monomer in cytosol
- Apoptotic signal triggers assembly of large protein platform that brings initiator
caspases together into large complexes
- Pairs of caspases associate to form dimers, resulting in protease activation. Each
caspase in dimer cleaves is partner at specific sites in protease domain which
stabilizes active complex & is required for proper function of enzyme in cell
find more resources at oneclass.com
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Document Summary
Called programmed cell death occurs by process called apoptosis: cells die by apoptosis undergo morphological changes. They shrink & condense, cytoskeleton collapses & nuclear envelope disassembles & nuclear chromatin condenses. & breaks into fragments: cell or apoptotic bodies become chemically altered so neighbooring cells or macrophage rapidly englufs them before they spill contents. Prevents damaging inflammatory response: cells that die in response to acute trauma or lack of blood supply by process called cell necrosis . Necrotic cells swell & burst spilling content over neighbors & results in inflammatory response. Could also be caused by energy depletion- leads to metabolic defects & loss in ionic gradients. Ne(cid:272)(cid:396)optosis is fo(cid:396)(cid:373) of p(cid:396)og(cid:396)a(cid:373)(cid:373)ed (cid:272)ells death that"s t(cid:396)igge(cid:396)ed (cid:271)y spe(cid:272)ifi(cid:272) (cid:396)egulato(cid:396)y signals from other cells. These proteins are called caspases: caspases are inactive & only active during apoptosis, two major classes of apoptotic caspases: Exist as inactive, soluable monomer in cytosol.
