Cells in multicellular organisms are specialized to perform different functions. This is called cell differentiation.

Here's why:

* Structure determines function: Cells have different shapes and internal structures based on their specific role. For example, muscle cells are long and fibrous to allow contraction, while nerve cells have long extensions to transmit signals.

* Gene expression: Not all genes are active in every cell. Some genes are turned on or off depending on the cell's function. This allows cells to express specific proteins and perform specialized tasks.

Here are some examples of different cell types and their functions:

* Nerve cells (neurons): Transmit electrical signals throughout the body.

* Muscle cells: Contract to produce movement.

* Red blood cells: Carry oxygen throughout the body.

* White blood cells: Fight infections.

* Skin cells: Protect the body from the environment.

* Bone cells: Form and maintain bone tissue.

* Plant cells: Carry out photosynthesis, provide structural support, and store nutrients.

Although cells may perform different tasks, they all share some basic characteristics, such as a cell membrane, cytoplasm, and DNA. They also rely on similar processes, like protein synthesis and energy production.