Which of the following correctly explains why the cell membrane only allows some substances through? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a The hard rigid texture of the membrane makes it difficult for anything to get through. b The phospholipids are very densely packed together creating a tight seal. c The alternating hydrophilic-hydrophobic-hydrophilic layers make the membrane semipermeable.
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Which of the following statements best describes a characteristic of biological membranes? A/ Phospholipids move laterally within the plane of the membrane. B/ Phospholipids are arranged with hydrophilic tails in the interior of the membrane. C/ Phospholipids generally occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. D/ Phospholipids never flip-flop from one layer of the membrane to the other. Which of the following statements best describes the structure of a membrane based on the fluid mosaic model? A/ The membrane is composed of a single layer of fluid phospholipids between two layers of hydrophilic proteins. B/ The membrane is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins. C/ The membrane is composed of a fluid bilayer of phospholipids between two layers of hydrophilic proteins. D/ The membrane is composed of a mosaic of fluid polysaccharides and amphipathic proteins.
Josee P.
Every cell is covered by a membrane that separates the cell from its outside environment. A major component of a cell membrane is its lipid bilayer, which is made of phospholipids. Phospholipids consist of two hydrophobic fatty acids joined by a glycerol molecule to a hydrophilic phosphate group. In the cell membrane, the hydrophilic heads of the phospholipids face outward and the hydrophobic tails face inward. How does the structure of phospholipids help them perform their function? A. It allows them to easily attach to substrates in the outside environment. B. It allows them to control the movement of substances into and out of the cell. C. It allows them to store energy and release it to the cellular environment. D. It allows them to store genetic information that can be used to make cell structures.
Madhur L.
In a cell membrane, explain why the lipid portion of the bilayer serves as a barrier to hydrophilic substances/solutes. What types of substances are able to pass through the phospholipid bilayer? Explain. What types of substances cannot pass through the phospholipid bilayer? Explain. In a cell membrane, explain how proteins make the membrane semipermeable and explain their role in homeostasis. What types of substances are able to cross the membrane via transport proteins? What types of substances do not cross the membrane via transport proteins? Describe the specificity of these types of proteins. Are large things like macromolecules transported across the membrane by transport proteins? Why not? How are large things (macromolecules, for example) transported in and out of the cell? Describe how endocytosis and exocytosis work. Is this active or passive transport? Are the processes in the table below exocytosis or endocytosis?
Shaiju T.
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