Table of Contents
- 1 What allows passage through the cell membrane?
- 2 What is the term for the nature of the cell membrane that allows some things to pass and not others?
- 3 Is osmotic pressure generated if solutes diffuse freely?
- 4 Why is the cell membrane said to be selectively permeable?
- 5 What are the solutes in a cell?
What allows passage through the cell membrane?
The plasma membranes of many cells also contain water channel proteins (aquaporins), through which water molecules are able to cross the membrane much more rapidly than they can diffuse through the phospholipid bilayer. Thus, specific channel proteins allow the passage of Na+, K+, Ca2+, and Cl- across the membrane.
What is the term for the nature of the cell membrane that allows some things to pass and not others?
The cell membrane is semipermeable (or selectively permeable). It is made of a phospholipid bilayer, along with other various lipids, proteins, and carbohydrates. The unique structure of the cell membrane allows small substances (like oxygen or carbon dioxide) to easily pass through.
What a cell membrane is because it allows only certain substances to enter or leave a cell?
The cell membrane is selectively permeable, or “semi-permeable”, meaning that the membrane only allows certain substances to enter or leave the cell.
Does the cell membrane allow solutes to enter the cell?
You might think that solutes will flow into our out of the cell until the solute concentrations are equal across the membrane. However, not all molecules can pass through the cell membrane. The plasma membrane (lipid bilayer) is significantly less permeable to most solutes than it is to water.
Is osmotic pressure generated if solutes diffuse freely?
No, if solutes diffuse, no osmotic pressure is generated.
Why is the cell membrane said to be selectively permeable?
The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Transport proteins make passage possible for molecules and ions that would not be able to pass through a plain phospholipid bilayer.
How is the cell membrane regulate the movement of materials into and out of the cell?
The cell membrane controls what goes in and out by having protein channels that act like funnels in some cases and pumps in other cases. Active transport requires energy, because protein machines actively grab molecules on one side of the membrane and push them through to the other side.
How do solutes cross the cell membrane?
Facilitated diffusion is a process by which solutes diffuse across membranes that they wouldn’t normally get through on their own. They pass through with the aid of transport proteins.
What are the solutes in a cell?
A solute is a substance dissolved in a liquid, the solvent: water in this Demonstration. Osmosis is the movement of water across a cell membrane. Cells use osmosis to maintain concentration equilibrium (the concentrations of solute inside and outside the cell are equal).