Answer:
It's not clear what you mean by "the cell membrane being thrown up in many folds along one side". However, one possible explanation for a folded cell membrane is the process of endocytosis.
Endocytosis is a cellular process by which the cell takes in material from the outside environment by engulfing it with a section of the plasma membrane. This section of the membrane then folds inward and forms a small pouch, which eventually pinches off to become a vesicle within the cell. This process can occur in several forms, including phagocytosis, pinocytosis, and receptor-mediated endocytosis.
During endocytosis, the cell membrane is temporarily folded or invaginated to form the vesicle that contains the material being taken in. This can result in the appearance of a folded membrane, as observed under a microscope. Once the vesicle is formed, it can be transported to other parts of the cell for various purposes, such as digestion, recycling, or secretion.
Overall, endocytosis is an important process for maintaining the homeostasis of the cell and is involved in a variety of cellular functions, including nutrient uptake, immune defense, and cell signaling.