What functions do membrane proteins serve? synthesize phospholipids for the maintenance and growth of the cell membrane transport nutrients into the cell that cannot otherwise cross the phospholipid bilayer transport wastes out of the cell that cannot otherwise cross the cell membrane prevent small, uncharged substances from crossing the phospholipid bilayer synthesize DNA within the cell using raw materials found outside the cell

transport nutrients into the cell that cannot otherwise cross the phospholipid bilayer transport wastes out of the cell that cannot otherwise cross the cell membrane

Explanation:

Cell membrane integral proteins especially trans-membrane proteins facilitate and regulate the movement of particular molecules across the cell membrane. Examples of these molecules are glucose and sodium ions. These molecules are either charged and cannot pass through the hydrophobic lipid layer of the cell membrane and/or are too large to pass through the cell membrane pores (like the aquaporins). Other types of cell membrane proteins are peripheral proteins. Collectively these proteins can have several other functions include cell signaling, enzymatic activity, cell-to-cell recognition, and etcetera.