Theories of Aging

Question 0

Error theories of aging

Answer 0

-Environmental assaults to living organisms that induce cumulative damage at various levels as the cause of aging.

Examples:

• Wear and tear
• Free radical
• Mitochondrial

Question 1

Programmed theories of aging

Answer 1

-Aging follows a biological timetable, perhaps a continuation of the one that regulates childhood growth and development.

Examples:

• Programmed senescence
• Neuroendocrine
• Telemorase
• Evolutionary

Question 2

Evolutionary theories of aging

Answer 2

• Decline in the force of natural selection
• Mutations that come into play in old age are relatively neutral to to natural selection because bearers have already reproduced (leads to mutation accumulation). E.g. Huntington’s disease.
• Life span is resulting from environmental factors (predation, cold, famine etc) and genetic components (e.g. planarian), and may represent a tradeoff between longevity vs reproductive fitness (disposable soma)
• Some genes are beneficial early in life but detrimental in later stages (antagonistic pleiotropy)

Question 3

Mutation accumulation

Answer 3

Accumulation of late-acting mutations that are passed on from generation to generation

Question 4

Antagonistic pleiotropy

Answer 4

Genes that are beneficial in early life can be detrimental in later stages. E.g. P53 (TP53) which protects against cancer but shortens lifespan.

Question 5

Disposable Soma theory of aging

Answer 5

Lifespan represents a tradeoff between longevity and reproductive fitness

Question 6

Wear and tear theory of aging

Answer 6

• Aging is a consequence of life itself, reflecting wear and tear on the organism
• Radiation, toxins, oxidative stress

Question 7

Wear and repair theory of aging

Answer 7

• Lifespan is reflecting the organism’s repair mechanisms’ ability to counteract wear and tear effect.
• Repair comes at a cost that influences fitness

Question 8

Telomere theory of aging

Answer 8

• the presence of telomeres serve to protect the cells
• premature aging syndromes are associated with shorter telomeres
• telomere shortening is a potential biological clock triggering cellular senescence
• preserving telomeres in the cells is a potential anti-aging cure

Question 9

What are free radicals?

Answer 9

• Unstable molecules that have a free electron
• Free radicals bind to other molecules in the organism causing damage to proteins and DNA
• Oxygen, when unstable, binds and creat Reactive Oxygen Species (ROS)
• Factors that increase the presence of free radicals are smoking, radiation, strenuous exercise, food consumption etc

Question 10

Free radical theory of aging

Answer 10

• aging is the accumulation of free radicals over time
• mitochondria are a major source of free radicals, with aerobic respiration (process of turning food into APT) leading to increased levels of ROS