Table of Contents
What is Cell?
In biology, a cell is the smallest structural and functional unit of an organism. Cells are the basic units of life.
A cell has a plasma membrane that surrounds its contents and separates it from its environment. The cell membrane is selectively permeable, meaning that it allows some things to enter and exit the cell while keeping other things out.
The cell membrane is composed of a lipid bilayer with proteins embedded in it. The proteins on the surface of the cell membrane can interact with other proteins on the surface of other cells, allowing cells to communicate with each other.
The cell membrane also contains receptors that can bind to hormones and other molecules outside the cell, triggering a response inside the cell.
The cell interior is filled with cytoplasm, which contains organelles such as the nucleus, mitochondria, and ribosomes. The nucleus contains the cells’ genetic material, and the mitochondria produce energy for the cell.
The ribosomes are responsible for protein synthesis. The cell also contains cytoskeleton proteins that give the cell its shape and help it move.
Cell Organelles
Cell organelles are small, specialized parts of a cell that carry out specific functions. Some organelles are found in all cells, while others are found only in certain types of cells. The organelles that are found in all cells are the plasma membrane, nucleus, cytoplasm, and mitochondria.
The plasma membrane is the boundary of the cell. It is a thin, flexible layer of lipid (fat) and protein that surrounds the cell and separates the inside of the cell from the outside environment. The nucleus is the largest organelle in the cell. It is a round, dense structure that contains the cell’s genetic material (DNA). The cytoplasm is the gel-like substance that surrounds the nucleus and contains the organelles of the cell. The mitochondria are the organelles that produce energy for the cell.
Endocytosis and Exocytosis
Endocytosis is the process by which cells absorb molecules by engulfing them in their cytoplasm. The cell membrane wraps around the particle or molecule and pinches off, creating a vesicle. The vesicle then moves to the cell’s interior, where the particle or molecule is released.
Exocytosis is the process by which cells expel molecules by ejecting them from the cell. The cell membrane wraps around the particle or molecule and pinches off, creating a vesicle. The vesicle then moves to the cell’s exterior, where the particle or molecule is released.
