Death Flashcards
What is the biochemical view of ageing?
That it is a highly regulated process that may determine reproductive life
What is the biological view of ageing?
That it is merely a consequence of having passed reproductive age
What is mitochondria the site of?
Oxidative metabolism
What are free radicals of oxygen?
Very reactive molecules which can react with every cellular component e.g. DNA, proteins and lipids
How are free radicals of Oxygen formed?
They are byproducts of oxidative phosphorylation (i.e. aerobic respiration) in the mitochondria
How are free radicals of Oxygen formed?
They are byproducts of oxidative phosphorylation (i.e. aerobic respiration) in the mitochondria
What can free radicals of oxygen cause?
Mutations
What is true of the leak of free radicals?
The rate is proportional to metabolism (almost)
What do free radicals act as a signal for?
They act as a signal to increase the expression of more respiratory chain enzymes.
This adds balance and a lower probability of free radicals escaping
What happens if the increase of respiratory chain enzymes cannot fix the problem of free radicals?
The mitochondria are stimulated to divide, and the % of impaired mitochondria become more important.
= clonality
What is the metabolic rate of Drosophilia (fruit flies) linked to?
Ambient temperature
A 10°C rise in temperature = metabolic rate doubles = lifespan halves
What is the metabolic rate of Drosophilia (fruit flies) linked to?
Ambient temperature
A 10°C rise in temperature = metabolic rate doubles = lifespan halves
What is true of Salvelinus fontinalis (brook trout) lifespan/metabolic rate?
Lifespan not normally >6 years
However – populations transferred to cold, resource poor lakes live at leats 24 years = delayed maturation
What is an example of an ‘immortal’ cell?
Cancer
What is the Warburg effect?
Cancer cells tend not to use their mitochondria.
What is true of neuronal mortality?
Neurons (and the information contained in the synapses they make) may be irreplaceable
What is the hay flick limit?
The number of times that normal human embryonic cells can divide before they succumb to senescence (death).
40-60 times
What percentage of neutrons die before we are bon?
80%
What ways doing cells die>
Apoptosis, autphagy and necosis
What is apoptosis?
Programmed cell death – highly regulated natural process
How many cells die via apoptosis?
c. 10 billion cells/day
c. 416 million/hour
What is autophagy in terms of cell death?
Self-eating cells – highly regulated catabolic process
What is necrosis in terms of cell death?
Unregulated
No chemical/ immune signals
Acute cellular injury
What causes cells to die via autophagy?
Periods of stress
e.g. nutrient scarcity and ATP is needed for apoptosis
What is the role of apoptosis?
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 caspases in apoptosis?
They are a family of cysteine proteases that serve as primary effectors during apoptosis to dismantle most cellular structure.
