Ageing Flashcards
What are the three characteristics of ageing?
- Progressive
- Universal
- Irreversible
What are the two branches of theories of ageing?
Programmatic and stochastic
What is genetic pleiotropy?
The selection pressure for a limited life span - there is a “cost” in evolutionary terms of living too long
What is the rate of living theory?
Small animals have a short life and higher metabolic rate
Body size, metabolic rate and lifespan may interact with stochastic theories via ______ - increased at higher metabolic rates.
Free radical generation
What are the two stochastic theories of ageing?
- Free radical theory
- Calorie restriction theory
How are free radicals formed?
- Some oxygen has a free radical
- Binds to H2O -> H2O2
- H2O2 processed -> OH radical
What are the actions of free radicals?
- Increase cross linking of collagen
- Inactivate enzymes
- Break DNA
- Peroxidise lipids
- Modify amino acids
What are the protective mechanisms against free radicals?
- Superoxide dismutase
- Catalase
- Glutathione
- S Transferases
- Exogenous antioxidants
Which two enzymes work together to convert free radicals to H2O + O2?
Superoxide dismutase + catalase
What is the mechanism of glutathione?
Tripeptide that interacts with oxygen free radicals
What is the role of Sir2 in the calorie restriction theory?
- Transcriptional silencing gene
- Maintains telomeres on ends of chromosomes
- Shortening related to but not a cause of ageing
How does the ECM change with age?
- Collagen becomes progressively cross linked
- Elastin becomes more fragmented, less recoil
- PGs - increased sulphated, lipid binding, decrease hylauronan, reduced water content
