Andrew P Smith Cells and Tissues Parts of a standard cell Cytoplasm – “cell matter” Cytoplasm is the watery environment inside the cell. This extra-cellular fluid consists of all of a cell's internal contents, and is mostly made of water. Cytoplasm includes salts, an assortment of organic molecules, including many enzymes that catalyze reactions, as well as water. The cytoplasm is separated from the watery extra-cellular fluid, which is outside, by the plasma membrane. It contains discrete membrane-enclosed structures called organelles. Each of the organelles performs a specific cellular function.Plasma membrane – 7.0nm thick the plasma membrane serves as the interface between the machinery in the interior of the cell and the extra-cellular fluid (ECF) that bathes all cells. The lipids in the plasma membrane are chiefly phospholipids like phosphatidyl ethanolamine and cholesterol. Phospholipids are amphiphilic with the hydrocarbon tail of the molecule being hydrophobic; its polar head hydrophilic. As the plasma membrane faces watery solutions on both sides, its phospholipids accommodate this by forming a phospholipid bilayer with the hydrophobic tails facing each other.Nuclear membrane - The nuclear membrane insures that the interior of the nucleus is isolated from a cell's cytoplasm, allowing two different environments to be maintained. The membrane has two layers that enclose a distinct space in between, and although marked by large pores, the membrane is very selective, permitting only certain substances to enter or leave the nucleus. In
