Ageing

Question 1

What are the three characteristics of ageing?

Answer 1

• Progressive
• Universal
• Irreversible

Question 2

What are the two branches of theories of ageing?

Answer 2

Programmatic and stochastic

Question 3

What is genetic pleiotropy?

Answer 3

The selection pressure for a limited life span - there is a “cost” in evolutionary terms of living too long

Question 4

What is the rate of living theory?

Answer 4

Small animals have a short life and higher metabolic rate

Question 5

Body size, metabolic rate and lifespan may interact with stochastic theories via ______ - increased at higher metabolic rates.

Answer 5

Free radical generation

Question 6

What are the two stochastic theories of ageing?

Answer 6

• Free radical theory

- Calorie restriction theory

Question 7

How are free radicals formed?

Answer 7

• Some oxygen has a free radical
• Binds to H2O -> H2O2
• H2O2 processed -> OH radical

Question 8

What are the actions of free radicals?

Answer 8

• Increase cross linking of collagen
• Inactivate enzymes
• Break DNA
• Peroxidise lipids
• Modify amino acids

Question 9

What are the protective mechanisms against free radicals?

Answer 9

• Superoxide dismutase
• Catalase
• Glutathione
• S Transferases
• Exogenous antioxidants

Question 10

Which two enzymes work together to convert free radicals to H2O + O2?

Answer 10

Superoxide dismutase + catalase

Question 11

What is the mechanism of glutathione?

Answer 11

Tripeptide that interacts with oxygen free radicals

Question 12

What is the role of Sir2 in the calorie restriction theory?

Answer 12

• Transcriptional silencing gene
• Maintains telomeres on ends of chromosomes
• Shortening related to but not a cause of ageing

Question 13

How does the ECM change with age?

Answer 13

• Collagen becomes progressively cross linked
• Elastin becomes more fragmented, less recoil
• PGs - increased sulphated, lipid binding, decrease hylauronan, reduced water content