Cells are the basic building blocks of all living things and come in two main types: eukaryotic and prokaryotic. Eukaryotic cells are more complex than prokaryotic cells and have specialized structures called organelles, such as mitochondria, chloroplasts, and ribosomes. The cell membrane encloses the cell, controls what enters and exits, and is composed of a double layer of phospholipids with embedded proteins.

Cells are the basic building blocks of all living things and come in two main types: eukaryotic and prokaryotic. Eukaryotic cells are more complex than prokaryotic cells and have specialized structures called organelles, such as mitochondria, chloroplasts, and ribosomes. The cell membrane encloses the cell, controls what enters and exits, and is composed of a double layer of phospholipids with embedded proteins.