Cell Death Flashcards
What is the link between size and lifespan and reproduction
Larger size means longer lifespan as smaller animals become reproductively active much younger.
Hence sometimes ageing increasing in rate after reproductive age.
What is ageing and link to free radical theory (theory)
The free radical theory of aging says that aging is caused by accumulation of damage inflicted by reactive oxygen species (ROS).
Damage to mitochondrial DNA that codes for;
some proteins of the mitochondria
respiratory chain enzymes
other nuclear components
Free radicals also act as a signal to increase the expression of more respiratory chain enzymes - balance
If increasing respiratory chain enzymes cannot fix the problem, mitochondria are stimulated to divide - % of impaired mitochondria become important - clonality
Mutations
Link of metabolic rate and lifespan
Faster metabolic rate = decreased lifespan
Why do birds live longer than they should?
Free radical leak vs antioxidant capacity fundamental
Birds in general have a reduction in oxidative damage. This means birds have lower levels of reactive oxygen species (ROS) or have developed strategies to reduce the damage associated with them. Birds also reduce damage from oxidative processes.
cancer cells
Cells can be immortalised – cancer
Cancer cells tend not to use their mitochondria
Warburg effect
Replicative Immortality
what is Hayflick limit?
what is telomere shortening?
Hayflick limit (40 – 60 divisions)
Telomere shortening (normally large) a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes.
Telomerase - expressed at functionally significant levels in the vast majority (90%) of spontaneously immortalized cells, including human cancer cells.
How do cells die?
3 ways
Apoptosis (programmed cell death)=Highly regulated natural process, 10 billion cells/day, 416 million/hour
Autophagy (self eating)= Highly regulated catabolic process
Necrosis= Unregulated, no chemical/immune signals
Acute cellular injury
What is Autophagy?
Self eating – at a cellular level
Degradation of organelles via a lysosomal pathway
Periods of stress – nutrient scarcity
What happens in Apoptosis and reasons?
Activation of caspases – proteases
Destruction of mitochondria
Destruction of DNA
Blebbing of cell membrane
Apoptotic body formation
Phagocytosis
Role:
Removal of damaged or old cells
Removal of cells that are not needed
Removal of cells that have lost control
What is the role of Mitochondria in Apoptosis and what happens?
Mitochondria are central to Apoptosis
Loss of mitochondrial membrane potential – stops ATP synthesis
Generation of pores in the membranes
Release of CytC and AIF
Nearly all of the proteins involved in apoptosis are bacterial in origin CytC, caspases etc
Neisseria gonorrhoeae
What are the 3 checkpoints that control cell division.
the G1 checkpoint; for size nutrients DNA damage and growth factors
the G2/M checkpoint; cell size and DNA replication
the spindle checkpoint; Check for chromosome attachment to spindle.
