Which of the following types of molecules can never move across the phospholipid bilayer of a cell membrane by simple diffusion? Group of answer choices Steroids Fats Lipids Ions

Cell membranes consist mainly of a _________. a. carbohydrate bilayer and proteins b. protein bilayer and phospholipids c. phospholipid bilayer and proteins

Cell membranes consists mainly of ________ and ________ . a. lipids; carbohydrates c. lipids; phospholipids b. phospholipids; protein d. phospholipids; ECM

For each of the following sentences, fill in the blanks with the best word or phrase selected from the dropdown list. Not all words or phrases will be used; each word or phrase should be used only once. The backbone amino group of every amino acid in an a-helix form a hydrogen bond with backbone carbonyl group of the amino acid four positions away. Therefore, the protein backbone is [Select] of the helix, with the amino acid side chains [Select] of the helix. For a single-pass transmembrane protein, the amino acids in the transmembrane segment have [Select] ✓side chains.