The phosphate group is negatively charged, making the head polar and hydrophilic—or “water loving.” A hydrophilic molecule (or region of a molecule) is one that is attracted to water. Despite differences in structure and function, all living cells in multicellular organisms have a surrounding cell membrane.

As the outer layer of your skin separates your body from its environment, the cell membrane (also known as the plasma membrane) separates the inner contents of a cell from its exterior environment. This cell membrane provides a protective barrier around the cell and regulates which materials can pass in or out

phosphate group — negatively charged, making the head polar and hydrophilic—or “water loving.” A hydrophilic molecule (or region of a molecule) is one that is attracted to water. cell membrane — membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane. hydrophilic — describes a substance or structure attracted to water. anticodon — consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an mRNA molecule.

Be able to describe the molecular components that make up the cell membrane; explain the major features and properties of the cell membrane; compare and contrast different types of passive transport with active transport, providing examples of each.