Organelles are small structures within cells that perform dedicated functions.
As the name implies, you can think of organelles as small organs. There are a dozen different types of organelles commonly found in eukaryotic cells. In this course we will focus our attentions on only a handful of organelles. We will examine these organelles with an eye to their role at a molecular level in the cell, and leave descriptive cell biology for another course. For example, our interest in the mitochondrion lies in its ability to generate energy in a form that is useful to the cell, and to that end we are interested in how the membrane structure allows the energy generation to proceed, but we will not spend much time naming mitochondrial structures or discussing their distribution in different cell types.