All living things are made of cells, which vary greatly in size but generally range from 10 to 1000 micrometers. The document outlines the key organelles found within cells, including the nucleus that controls the cell, mitochondria that generate energy, the endoplasmic reticulum and ribosomes that produce proteins, and chloroplasts in plant cells that capture sunlight to produce food. It also notes that cells are surrounded by a cell membrane and some have additional protective cell walls, with various organelles like vacuoles, lysosomes, and Golgi bodies serving specialized storage and transport functions within the cell.
