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Biology Of Ageing Year2 > Evolution And Theories Of Ageing > Flashcards

Evolution And Theories Of Ageing Flashcards

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1
Q

What is ageing?

A

Progressive loss of function accompanied by decreasing fertility and increasing mortality with advancing in age.

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2
Q

When does fertility in women stop?

A

45-50 years old

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3
Q

Why do women stop being fertile?

A

We have a finite number of egg cells, eventually we run out of coccyges.

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4
Q

What is the issue with proximate cause of women becoming infertile?

A

Why wouldn’t natural selection not produced a longer lasting ovary.

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5
Q

Why would the difficulty of birth lead to women becoming infertile later in life?

A

May be a fitness advantage to limiting reproduction to ages when it is comparatively safe so women can raise existing offspring to independence

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6
Q

Why is the ‘grandmother hypothesis’?

A

Woman avoid danger of childbirth but benefit as a grandmother to help care for offspring.

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7
Q

Why do we age?

A

Diversity in longevity betweenspecies show there maybe genes for ageing

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8
Q

Is ageing programmed?

A

No

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9
Q

How do we know ageing isn’tprogrammed?

A
  • There is no evidence of ageing genes
  • Group selection necessary for ageing doesn’t work
  • selection is weak at old age
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10
Q

How does extrinsic mortality drive ageing?

A

Sources of extrinsic mortality imposes a limit on life span
Genes are selected to ensure survival for expected lifespan and no more

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11
Q

What are evolutionary theories of ageing?

A
  1. Mutation accumulation
  2. Antagonistic pleiotropy
  3. Disposable soma
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12
Q

Who came up with the mutation accumulation theory?

A

Peter Medawar in 1952

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13
Q

What is the mutation accumulation theory?

A

Deleterious mutations are selected against at a young age.
Expressed at a later stage of life because you have already passed on your genes.
Selection is weaker later in life.

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14
Q

Why is selection weaker in life?

A

Extrinsic mortality
Mutation accumulate

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15
Q

What is Huntington’s disease?

A

Genetically determined (dominant)
Neurological disorder
Severe symptoms

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16
Q

When does Huntington’s disease occur?

A

40-50 years (after reproduction)

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17
Q

What disease proves the mutation accumulation theory?

A

Huntington’s disease because it occurs after reproduction.

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18
Q

What is in antagonistic pleiotropy theory of aging?

A

Mutations that are beneficial early in life (before reproduction) but are deleterious later in life do not get selected out of a population because selection is less efficient later in life.

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19
Q

How is oestrogen an example of antagonistic pleiotropy?

A

In early life it provides higher fertility but later in life high levels of oestrogen may lead to breast cancer.

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20
Q

Who came up with the antagonistic pleiotropy theory?

A

George Williams in 1957

21
Q

What is the evidence for a genetic contribution to ageing?

A

Comparing longevities of mono- and di-zygotic twins suggest that 25% of variability in ageing is explained by genes.

22
Q

What is the issue with the evidence for a genetic contribution to ageing?

A

Some studies suggest only 10% of the variability in longevity is explained by genes.

23
Q

What is the disposable soma theory?

A

Ageing is caused by accumulation of damage.
Deprivation orresources
Maintenance vs. Reproduction

24
Q

What predictions are made in the disposable soma theory?

A

Multiple types of damage.
Long-lived species should have better defences and accumulates damage more slowly.

25
Q

Who came up with the disposable soma theory?

A

Tom Kirkwood in 1977

26
Q

What is the accumulation of molecular damage?

A

Free radical/oxidative
Protein and DNA copy error
Other sources of damage including glucose, toxin and uv

27
Q

Which theory is correct for ageing?

A

The 3 theories are not exclusive and provide complementary explanations for why ageing occurs.

28
Q

What is the main prediction for the disposable suma theory?

A

The allocation strategy will respond to environmental variation and the rate of ageing may be altered.

29
Q

How does mortality change with age?

A

Mortality increases exponentially

30
Q

Why is the fact woman stop reproducing so strange?

A

Only mammals to stop being capable of reproducing.

31
Q

What is the mortality rate fer human births?

A

10%, birth is way safer in all other mammals.

32
Q

Why is life expectancy going up?

A
  • Hygiene
  • Medical care
  • child mortality decreases
  • late life mortality extended.
33
Q

Why can higher life expectancy going up going to be a problem?

A

Higher life costs
Over population.

34
Q

Why is there no evidence for ageing genes?

A

Because there has never been any mutations that have resulted in living forever.

35
Q

What is evolutionary group selection?

A

Dying to make space for your kin.

36
Q

What are mono-zygotes twins?

A

Exactly the same genome.

37
Q

What is the most important thing in maintenance in the body?

A

All systems should carry the same protection level as there is no point repairing DNA if you’ll die due to protein turnover.

38
Q

How does the allocation of energy change based on age?

A

Fertility goes down and allocation maintenance increases.

39
Q

What is the difference between long and short lived species regarding the disposable soma theory?

A

In long live species damage accumulate slower and the protective mechanisms are much better.

40
Q

What is oxidative stress?

A

Damage caused by the by products of metabolism
Mitochondria can produce superoxides.

41
Q

What are superoxides?

A

Reactive oxides that can damage macromolecule

42
Q

How does oxidative stress accumulate over time?

A

After half life span evidence of damage first shown.
After that damage increases exponentially.

43
Q

What is Ros?

A

Relative oxygen species

44
Q

What is specific about the ros in long lived species?

A

Release long live but less reactive ros
Should have more effective repair systems.

45
Q

What is the hayflick limit?

A

Proliferating cells have a dividing limit after that they become senescent cells.

46
Q

What are senescent cells?

A

Damage cells
If you remove them in mice, heath is restored and they live longer.

47
Q

How does feeding affect ageing?

A

Can increase life span by reducing feeding, proved by mice.

48
Q

Why does a reduction in feeding lead to a reduction in ageing.

A

Work to change internal condition to survive on less so higher survival in them.

Biology Of Ageing Year2 (23 decks)

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