Molecular mechanisms and biological functions of Cell senescence and Apoptosis or PCD.

1. CELL SENESCENCE & PROGRAMMED CELL DEATH DR. JAYAKARA BHANDARY M. SENIOR SCALE LECTURER IN BOTANY GOVERNMENT ARTS AND SCIENCE COLLEGE KARWAR -581301, KARNATAKA, INDIA jaikarb@yahoo.com PRESENTED IN: EDUSAT BASED TRAINING PROGRAM FOR PU TEACHERS OF KARNATAKA DEPARTMENT OF PRE-UNIVERSITY EDUCATION, GOVT. OF KARNATAKA 2008

3. Cell senescence Organismal senescence Death.

6. Accumulation of Lipofuscin pigment.

7. Nuclear pyknosis.

9. Loss of ribosomal RNA.

10. Decline in transcription .

11. Decline in protein synthesis.

12. Stiffening of collagen .

14. Decrease in granular ER.

15. Degeneration of mitochondria.

17. Senescent fibroblast cells

19. Studied mainly in animal cells.

25. Alters membrane permeability.

26. Damage DNA / Proteins.

28. Immune theory – Antibodies against body’s own cells – autoimmune responses.

30. Understanding formation of cancerous cells - Failure of senescence mechanism?

36. Activated to kill cells by death signals.

39. Fragmentation of DNA/Nucleus.

41. Digestion of apoptotic bodies by macrophages – Phagocytosis.

43. A normal cell

47. A normal cell An apoptotic cell

48. Procaspase activation

49. Caspase activation cascade

54. Cells of the tadpole tail undergo apoptosis during metamorphosis into a frog

55. 131 of 1090 cells undergo apoptosis in Coenorhabditiselegans (Nematode).

59. Disappearance of cytoplasm

61. Destroying pathogen infected cells.

63. Cells of wheat seedling undergoing apoptosis Apoptotic vacuoles with cellular debris

65. Certain auto-immune diseases are due to failure of apoptosis in cells which should die.