Cells and Tissues
Cells are composed of their cytoplasm, which includes the cytosol and organelles, the nucleus and the surrounding plasma membrane. You should know that the plasma membrane is a double layer of phospholipid molecules and that these molecules have a hydrophilic end and a hydrophobic end. The plasma membrane contains proteins including the ATPase (the sodium-potassium pump) which moves sodium ions out of the cell while moving potassium ions into the cell. Other proteins act as receptors and as pores or gateways into the cell. You should know the names and function of some of the organelles within cells. For example, you should know that mitochondria produce ATP and that ribosomes synthesise proteins from amino acids.