Cell Membrane Flashcards, test questions and answers

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What is Cell Membrane?

The cell membrane, often referred to as the plasma membrane, is a thin and flexible barrier that surrounds the entire surface of a cell. It is composed mainly of proteins and lipids, which form a double layer known as a phospholipid bilayer. The cell membrane functions as both a barrier and an interface between the inside of the cell and its external environment. It allows certain substances to enter or leave the cell while keeping out other substances.The lipid bilayer consists mainly of two types of molecules: phospholipids and cholesterol. Phospholipids are amphiphilic molecules; they have both hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. Cholesterol helps stabilize the structure of the membrane by inhibiting movement between phospholipids in different layers, which helps keep it impermeable to most solutes. Additionally, proteins embedded in this bilayer act as transporters for transporting specific molecules across the membrane or allowing communication between cells via receptor-ligand interactions. In addition to controlling what enters and exits the cell, the cell membrane also plays an important role in cellular metabolism by providing structural support for enzymes involved in metabolic pathways such as respiration or photosynthesis. It also serves as an attachment site for cytoskeletal elements like microtubules, which are involved in processes like endocytosis, exocytosis, intracellular transport, and motility within cells. In conclusion, the cell membrane is essential for maintaining homeostasis within cells by regulating what enters or exits them while also providing structural support for necessary metabolic pathways within them.