Plasma membrane is made up of lipids and proteins synthesised by rough endoplasmic reticulum and smooth endoplasmic reticulum respectively. In plasma membrane the integral proteins help the things to go in and out. Its structure contains heads(hydrophilic) and tails(hydrophobic). It also possess carbohydrates. It allows the flow of water from higher concentration to lower concentration(osmosis).

Plasma Membrane - Cell the Unit of Life, Biology, Class 11

The plasma membrane is a crucial component of a cell that separates the internal environment of the cell from the external environment. It is a selectively permeable barrier that allows the entry and exit of certain substances, ensuring the cell's survival and proper functioning. Let's discuss some key aspects of the plasma membrane and address any doubts or problems related to this topic.

Structure of the Plasma Membrane:
- The plasma membrane is composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules arranged with their hydrophilic heads facing outwards and their hydrophobic tails facing inwards.
- Embedded within the phospholipid bilayer are various proteins that play important roles in cell signaling, transport of molecules, and other cellular processes.
- The membrane also contains cholesterol molecules, which help maintain the fluidity and stability of the membrane.

Functions of the Plasma Membrane:
- Selective Permeability: The plasma membrane controls the entry and exit of substances into and out of the cell. It allows the passage of small, non-polar molecules through simple diffusion, while larger or charged molecules require specific transport proteins.
- Cell Signaling: The membrane contains receptor proteins that can recognize and bind to specific signaling molecules, initiating cellular responses.
- Cell Adhesion: Proteins present on the membrane facilitate cell-to-cell adhesion, maintaining tissue integrity and forming specialized structures like tight junctions and gap junctions.
- Transport: The membrane contains various transport proteins, such as channel proteins and carrier proteins, which facilitate the movement of ions, nutrients, and other molecules across the membrane.

Doubts and Problems:
- If you have any doubts regarding the structure of the plasma membrane, its composition, or the functions of specific proteins embedded in the membrane, feel free to ask for clarification.
- If you are struggling to understand the concept of selective permeability or the mechanisms of molecule transport across the membrane, I can provide detailed explanations and examples.
- If you have any questions regarding the role of the plasma membrane in cell signaling or cell adhesion, I can help clarify those aspects as well.

Feel free to ask any further questions or share any specific problems or doubts you have regarding the plasma membrane.