Problem 7 - Biology of Aging

Question

Explain how the fatty acids found in normally functioning cellular membranes also play an important role in the degradation of membranes during leaf senescence.

Step-by-Step Solution

Answer

Fatty acids, being key components of membrane phospholipids, form a major part of cellular membranes. During leaf senescence, the process of aging in plants, enzymes called phospholipases are activated to cleave fatty acids from the phospholipids. These free fatty acids, besides undergoing further breakdown to provide energy, also aid in membrane disintegration. Therefore, fatty acids play a critical role in the degradation of membranes during leaf senescence.

Step 1: Understanding the role of Fatty Acids in Cellular Membranes

Fatty acids are the major components of phospholipids, which are the building blocks of cellular membranes. The hydrophobic (water-repelling) tails of these fatty acids align to form the interior of the phospholipid bilayer, thus creating a barrier that separates the cell from its external environment.

Step 2: Explaining Leaf Senescence

Senescence is the process of aging in plants - it's a phase in a leaf's life cycle where its metabolic functions slow down and eventually stop. It is a highly regulated and active process, involving degradation of cellular structures and redistribution of their nutrients to other parts of the plant.

Step 3: Connecting Fatty Acids with Senescence

During senescence, breakdown of cellular structures, including membranes, occurs. Fatty acids play a crucial part here. The enzymes named phospholipases are activated, which cleave fatty acids from the phospholipids creating free fatty acids. Those free fatty acids then undergo further breakdown, providing an energy source for the senescing leaf, aiding degradation.