BIO 1140 Lecture Notes - Lecture 5: Cytoskeleton, Cathepsin, Chromatin

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Topic 5 Mitochondria and Cell Death
Cell Biology
Kristen Batten, 8616820
Thursday, February 9TH, 2017
- Calcium Regulation:
o Concentration gradient: channels/transporters
o Binding proteins: calsequestrin, calbindin, paravalbumine
o Compartmentalisation: ER/Mitochondria Channels/ Trabsporters
o Replenish reserves
- What and how do cells die?
o Necrosis and apoptosis
Necrosis: the death of most or all of the cells in an organ or tissue due to
disease, injury, or failure of the blood supply. It does not have blebbing
but it does have swelling, lysis, and lysosomal membrane degradation.
Normal cell swelling (reversible) swelling (irreversible -
disintegration
Apoptosis: the death of cells that occurs as a normal and controlled part
of an organisms growth or development
Normal cell condensation fragmentation apoptic bodies
Apoptosis does not occur only in response to negative stressors
its a essetial part of deelopet
o The size of an organ or organism depends on the total cell mass; the cell number
must be controlled
Total cell number: cells can grow, cells can divide or die
o Healthy and not healthy cells need to die
o The mechanism for why/how they die may be different
- What are the triggers of cell death?
o Chemical messengers
Growth factors
Mitogens (cell division)
Survival factors
o Stress (toxicity, damage, dyshomeostasis, etc.)
o Cell cycle checkpoints
o All of the reasos for ell death lead to hages i the ell hih lead to its
demise
o The mechanisms ho are differet
- Necrosis: The Calpain cathespin pathway
o Calpain is a calcium dependant protease: it degrades the lysosomes membrane
Changes it from selectively permeability
Changes to certain types of membrane transport (facilitated diffusion)
Therefore , increase in calcium
The cell will die because the rise in calcium activates calpain
In the lysosome at a low pH it is not very active
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