Problem 9 - Biology of Aging

Question

Discuss the differences between animal and plant mitotic cell senescence.

Step-by-Step Solution

Answer

The main differences between animal and plant cell senescence include the role of telomeres, the presence of totipotent cells and the alternation of generations in plants. Animal cell senescence involves the shortening of telomeres until they are too short for the cell to divide anymore. On the other hand, plant cells can bypass senescence due to the presence of totipotent cells that can continue to divide and differentiate, along with an alternation of generations that allows for a reset in the aging process.

Step 1 - Understanding Cell Senescence

Cell senescence is the state where the cell loses the ability to divide, leading to a cessation of growth. Some of the common triggers can be DNA damage, oxidative stress, telomere shortening, etc.

Step 2 - Animal Cell Senescence

Animal cell senescence often involves the shortening of telomeres, which are the protective caps at the ends of chromosomes. Every time an animal cell divides, these telomeres get shorter until finally they are so short that the cell cannot divide anymore. In addition to this, DNA damage or other forms of stress can also trigger senescence. Animal cells also have a disorganization of the chromatin structure and decreased metabolic activity, among other traits.

Step 3 - Plant Cell Senescence

Plant cells differ from animal cells in their ability to bypass senescence. Unlike animal cells, plant cells do not rely on telomeres for their longevity. Instead, they can remain 'young' due to the presence of totipotent cells, capable of continuous division and differentiation. Plant cells also have an alternation of generations, which gives them a chance to reset the cellular aging process.