Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions..
There are two distinct types of cells: prokaryotic cells and eukaryotic cells. Though the structures of prokaryotic and eukaryotic cells differ (see prokaryote, eukaryote), their molecular compositions and activities are very similar. The chief molecules in cells are nucleic acids, proteins, and polysaccharides.
The Four Main Types of Cells Epithelial Cells. These cells are tightly attached to one another.,Nerve Cells. These cells are specialized for communication.,Muscle Cells. These cells are specialized for contraction. Connective Tissue Cells.
