Inside the cell wall lies the thin, cytoplasmic cell membrane. The cell membrane is composed of lipid and protein and regulates the passage of substances into and out of the cell, such as metabolites and waste products. Important metabolites are taken up by active transport as the cell membrane is relatively impermeable. The cell membrane is also the first barrier to toxic materials entering the cell and is important in degredation of extra-cellular nutrients. | Inside the cell wall lies the thin, cytoplasmic cell membrane. The cell membrane is composed of lipid and protein and regulates the passage of substances into and out of the cell, such as metabolites and waste products. Important metabolites are taken up by active transport as the cell membrane is relatively impermeable. The cell membrane is also the first barrier to toxic materials entering the cell and is important in degredation of extra-cellular nutrients. |