Cell Membrane

What is a Cell Membrane?

A cell is the structural and functional working unit of life and an organism’s building components and fundamental unit. In 1665, an English scientist named Robert Hooke created the term cell. The roles and compositions of the cells determine the shape and size of the cells. There are various types of cells, distinguished by the presence or absence of a few cell organelles. Plasma membrane( cell membrane) encloses all cell components, including its cytoplasm and organelles. It protects a cell’s cytoplasm while also maintaining the cell’s structure. Since plant cells include a cell wall that encloses the cell membrane, the cell membrane is not  the cell’s outermost layer in all organisms. On the other hand, animal cells do not have a cell wall. Thus the cell membrane acts as a barrier between the inside contents of the cell and the outside environment. During cell division, the cell membrane plays an essential role in cytokinesis. Certain species use cilia to change their membranes for eating and movement.

Functions of a Cell membrane

The primary cell membrane functions include:

• Maintaining the integrity of cells inside
• Providing support and preserving the cell’s form
• By balancing endocytosis and exocytosis, it aids in cell growth regulation
• The cell membrane also influences cell signaling and communication
• It functions as a selectively permeable membrane, enabling only certain chemicals to enter the cell

Cell Membrane Structure

Proteins and lipids make up the majority of the cell membrane structure. Lipids can make up anywhere from 20% to 80% of a membrane, depending on its location and function in the body, with proteins accounting for the rest. Proteins monitor and regulate the cell’s chemical environment and assist in the movement of molecules across the membrane while lipids help to give membranes their flexibility.

Important Terms Related to Cell Membrane

Here are the important terms related to the cell membrane;

• Cell Membrane Lipids

Phospholipids make up a significant portion of cell membranes. Phospholipids create a lipid bilayer with their hydrophilic (water-loving) head areas facing the aqueous cytosol and extracellular fluid. The hydrophobic (water-repelling) tail areas face away from the cytosol and extracellular fluid. Only specific compounds can diffuse through the membrane because of the lipid bilayer. Cholesterol is a lipid that is found in animal cell membranes. Cholesterol molecules are distributed between membrane phospholipids preferentially. Preventing phospholipids from being too closely packed together helps protect cell membranes from becoming stiff. Cholesterol is not found in plant cell membranes. Glycolipids are lipids with a carbohydrate sugar chain attached that are found on cell membrane surfaces. They aid the cell’s recognition of other body cells.

• Cell Membrane Proteins

There are two types of linked proteins in the cell membrane. Peripheral membrane proteins are found outside the membrane and are connected by interactions with other proteins. The majority of integral membrane proteins pass through the membrane after being introduced. Portions of these transmembrane proteins are exposed on both sides of the membrane. Membrane proteins serve a variety of purposes in cells.

• Structural proteins aid in the support  of the cell

Cell membrane receptor proteins use hormones, neurotransmitters, and other signalling substances to assist cells in communicating with their external environment. Transit proteins, such as globular proteins, enable the transport of chemicals across cell membranes. A carbohydrate chain is connected to glycoproteins. They are embedded in the cell membrane and assist in cell-to-cell communication as well as chemical transport across it.

• Organelle Membranes

Protective membranes wrap several cell organelles as well. Membrane-bound organelles include the endoplasmic reticulum, nucleus, Golgi apparatus, vacuoles, lysosomes, etc. A double membrane connects both mitochondria and chloroplasts. The molecular membrane composition of different organelles varies and is well adapted to the roles they perform. Protein synthesis, lipid generation and cellular respiration are all dependent on the integrity of organelle membranes.

Cell Wall

Plant cells have a cell wall that protects them from the elements. It exists outside the cell membrane and has a tough, flexible and occasionally hard texture. It is mostly cellulose, long carbohydrate fibres such as hemicellulose, lignin and pectin. The cell wall’s principal roles are:

• Defending the cell from physical harm and pathogen invasion
• Regulates and controls cell growth direction
• Providing the cell with strength, structural support, and the ability to keep its shape
• Acts as a storage unit, storing carbohydrates for plant growth, particularly seed growth
• It allows smaller molecules to pass through it effortlessly

Things to Remember Based on Cell Membrane

• A cell membrane is a sort of plasma membrane that encircles a cell and all of its elements, including cytoplasm and organelles
• Plasma membranes are found in the membranes of many different organelles
• Organelle plasma membranes may be different from cell membranes
• Selective permeability allows cell membranes and other plasma membranes to control the flow of substances across them
• The cell membrane participates in cytokinesis during cell division
• The cell membrane protects the cell against bacterial and viral invasion

Conclusion

All living things, including plants, have a cell membrane. In animals, it is the cell’s outermost layer, which encloses other cellular organelles. Unlike the cell wall, the cell membrane is flexible and can change form as needed. It also exhibits selective permeability and is metabolically active.