Cell Membrane

The cell membrane, also known as the plasma membrane, is a thin, flexible barrier that surrounds the cell. It is made up of a double layer of lipids (fats) with proteins embedded in it. The main function of the cell membrane is to protect the cell from its surrounding environment and to control the movement of substances in and out of the cell.

Structure of the Cell Membrane

The cell membrane is composed of phospholipid molecules, which have a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. These molecules arrange themselves in a double layer, with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards. Embedded within this lipid bilayer are various proteins that serve different functions, such as transport, signaling, and cell recognition.

Functions of the Cell Membrane

1. Selective Permeability: The cell membrane is selectively permeable, meaning it allows only certain substances to pass through while blocking others. This helps the cell maintain internal balance and respond to changes in its environment.

2. Cell Signaling: The proteins in the cell membrane play a key role in cell signaling, which involves communication between cells and the environment. These proteins can receive signals from outside the cell and initiate a response inside the cell.

3. Transport: The cell membrane regulates the transport of molecules in and out of the cell through various mechanisms such as diffusion, facilitated diffusion, and active transport.

Study Guide

Here are some key points to remember about the cell membrane:

1. What is the main function of the cell membrane?
2. Describe the structure of the cell membrane.
3. Explain the concept of selective permeability.
4. How do proteins in the cell membrane contribute to cell signaling?
5. What are the different mechanisms of molecular transport across the cell membrane?

Understanding the structure and function of the cell membrane is essential for comprehending how cells interact with their environment and maintain homeostasis.