Cellular Ageing Flashcards
Theories of aging
Telomerase theory
Free radical theory ( most common accepted)
DNA damage
Cross linking of collagen
Explain telomere-telomerase hypothesis
Telomere- a short sequence at the end of the chromosome
Usually ttaggg
Called as biological clocks
- as they short cellular aging occurs
Telomerase- it is used to rebuild telomeres very active in germ cells.
Inhibits cellular aging
Absent / low acting in somatic cells
Telomerase also called a immortality gene
What is hay-flick limit
Normal cell undergoes 60-70 cell divisions in life span
How carcigenosis occouss
Here telomenase Is activated all the gym
What is Werner syndrome
Defect in Dna Helicases
Premature aging
Wermer syndrome
Menl syndsome
What is free radical theory?
It is caused by progressive and reversible molecules oxidative damage due to oxidative stress in normal cells they are removed as in the old age they are failed to removed and cause oxidative damage
DNA damage role in cellular aging
Here longer exposure of DNA To physical, chemical, biological agents exogenously and endogenous ros species exposure target DNA and mitochondrial DNA as the age increases the repair mechanisms fail
Eg Werner syndrome_ DNA helicase deficient
Mitochondrial dysfunction
With aging mitochondrial production of ATP declines and oxygen free radicals rise especially h2o2 . Superoxide ion
Reduced number of mitochondria megamitochondia and vacuolization and disturbed criastae in senescent cells
Caloric regulation theory?
Calorie restriction delays aging it delays aging it reduces release of growth factors such as gh, insulin, insulin like growth factor and delays aging
Name all theories
① telomere telomerase hypothesis ② DNA damage ③ free radical damage ④ cross linkage of collagen ⑤ mitochondrial damage ⑥ calorie regulation theory ⑦ reduced autophase ⑧ altered gene expression
Explain alter gene expression
With age there is reduced Gene expression and proteins production with mitochondrial function other changes epigenetic expression that is reduced acetylation Methylation
What are sirtuins
They increase life spa.n
Protein deacetylases nad dependent
Sirtuine levels can be increased by calorie restriction wine consumption
They also have role in diabetes cancer agent
They reduce aging by preventing harmful effect of ros reduce apoptosis reduce metabolic activity
Organ changes in heart during aging
Atherosclerosis Arteriosclerosis with calcification Moncke berg's medial calcification. Brown atrophy of heart Major arterial trunk dilation
Nervous system changes
Alzheimer’s
Parkinson’s disease
Atrophy of gyri and sulci
