Question

Animals exploit the phospholipid asymmetry of their plasma membrane to distinguish between live cells and dead ones. When animal cells undergo a form of programmed cell death called apoptosis, phosphatidylserine-a phospholipid that is normally confined to the cytosolic monolayer of the plasma membrane-rapidly translocates to the extracellular, outer monolayer. The presence of phosphatidylserine on the cell surface serves as a signal that helps direct the rapid removal of the dead cell. How might a cell actively engineer this phospholipid redistribution? Choose one: • by inactivating both a flippase and a scramblase in the plasma membrane by boosting the activity of a flippase in the plasma membrane by inactivating a scramblase in the plasma membrane by inverting the existing plasma membrane by activating a scramblase and inactivating a flippase in the plasma membrane

Answer 1

Ans- by activating a scramblase and inactivating a flippase in the plasma membrane.

Phosphatidylserine is a phospholipid that is abundant in the eukaryotic plasma membranes. An ATP dependent enzyme called flippase normally keeps phosphatidylserine inside the cell, but the phosphatidylserine is exposed by the action of scramblase on the cell's surface in biological processes such as apoptosis and platelet activation.