The theory of ageing Flashcards
Dietary restriction and the suppression of particular chemicals appear to slow ageing. True or false?
True.
In C. elegans, a mutation in what gene has been shown to slow ageing?
Daf-2
In drosophila, a mutation in what gene has been shown to slow ageing?
Chico
In mice, a mutation in what gene has been shown to slow ageing?
lgf-1
Define ageing.
Refers to the passing of time and its effect on something. Can have both negative or positive connotations.
Define senescence.
The decline of fitness in an individual due to increasing age that has caused internal deterioration.
Define gerontology.
The study of the biological, psychological and social effects of ageing.
Define geriatrics.
The branch of medicine that deals with age-related illness.
The study of demographic senescence is interested in which factors?
Things like mean and median lifespan of a population.
The oldest human in the world was Madame Jeanne Calment, who died in 1993 at the age of?
122.
As you age the probability of dying increases. What kind of growth curve would this produce on a graph?
Exponential.
‘Testosterone dementia’ causes an elevated number of deaths in the 16-20 age bracket. What does this refer to?
Deaths in young people from stupid behaviour or suicide.
Is ‘testosterone dementia’ higher in males or females?
Males.
Define the Gompertz Law of 1825.
Mortality increases exponentially with age.
Define the Gompertz parameter.
A slope of log mortality against age.
What does MRTD stand for?
Mortality rate doubling time.
What is the MTRD for humans?
8 years.
Why have diseases like Huntingdon’s, which is highly damaging, not been removed by natural selection?
Because they have late onset - for example the average age of onset for Huntingdon’s is 35.5years. The selection pressure to remove them is low as they do not affect an individual during development or at prime reproductive age.
What is the basic principle regarding mutation and age?
Mutations with deleterious effects later in life are subject to weaker selection pressures.
Define intrinsic mortality.
Even without ageing, most species have an intrinsic mortality due to predation, starvation etc.
What is the mutation accumulation theory?
Mutations that are active early in life have a strong selective pressure and are removed. Mutations acting later in life have a weak selective pressure and are allowed to accumulate. This accumulation causes ageing.
Define the antagonistic pleiotropy theory.
Some mutations are beneficial early on in life, but then become deleterious later on. These mutations are tolerated by natural selection as they aid survival in youth, and more organisms are likely to survive during youth than to survive to old age.
What is another name for the antagonistic pleiotropy theory?
The trade-off theory.
In general which is more widely accepted, the mutation accumulation or antagonistic pleiotropy theory?
Antagonistic pleiotropy.
