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The speed doesn't necessarily determine the permeability, but the size does. Smaller molecules such as O2 can easily enter the cell while CO2 leaves the cell. There are other criteria that also determines whether a molecule can pass through the plasma membrane such as its solubility. Fat soluble molecules such as steroids can easily pass through the membrane.
Oxygen molecules are small and nonpolar, which allows them to easily pass through the hydrophobic lipid bilayer of the cell membrane via simple diffusion. Glucose molecules, on the other hand, are larger and polar, making it more difficult for them to move through the nonpolar interior of the lipid bilayer. They require specific transport proteins or channels to facilitate their movement across the membrane.
That is a semi-permeable membrane.
Also small molecules.Basically because the cell membrane is amphipathic; a polar head and non-polar tails make up the double layered membrane with non-polar tails sticking inward and polar heads outward. This means that the non-polar middle, the lipid part, does not allow hydrophyllic substances to pass easily through the membrane while non-polar substances can pass through easily. Having to do with charge and solubility.
means that the cell membrane has some control over what can cross it, so that only certain molecules either enter or leave the cell
The speed doesn't necessarily determine the permeability, but the size does. Smaller molecules such as O2 can easily enter the cell while CO2 leaves the cell. There are other criteria that also determines whether a molecule can pass through the plasma membrane such as its solubility. Fat soluble molecules such as steroids can easily pass through the membrane.
Glucose is too big to pass throught.
Oxygen molecules are small and nonpolar, which allows them to easily pass through the hydrophobic lipid bilayer of the cell membrane via simple diffusion. Glucose molecules, on the other hand, are larger and polar, making it more difficult for them to move through the nonpolar interior of the lipid bilayer. They require specific transport proteins or channels to facilitate their movement across the membrane.
That is a semi-permeable membrane.
Glucose is too big to pass through.
Cell membrane is semipermeable and oxygen molecules have size required for easy passqge while Glucose molecules do not have that size required for easy passage.
Also small molecules.Basically because the cell membrane is amphipathic; a polar head and non-polar tails make up the double layered membrane with non-polar tails sticking inward and polar heads outward. This means that the non-polar middle, the lipid part, does not allow hydrophyllic substances to pass easily through the membrane while non-polar substances can pass through easily. Having to do with charge and solubility.
means that the cell membrane has some control over what can cross it, so that only certain molecules either enter or leave the cell
Waste can pass through a membrane due to its size and composition. Membranes have small pores or channels that allow smaller molecules or ions to pass through, while larger molecules or particles are blocked. Additionally, the chemical properties of the waste may also play a role in its ability to pass through a membrane.
The property of a membrane or other material that allows some substances to pass through it more easily than others.Selective permeability refers to the control that a cell membrane has in terms of what it allows to cross it. This gives the cell membrane the ability to choose which molecules enter or leave.
When a cell's membrane is permeable, it means that only certain proteins and other molecules can go in and out of the porous membrane, through protein pumps and other pathways. Some molecules stay inside the cell, while others float outside. Starches, for example, are large molecules that cannot pass through the membrane.
molecule A is a SImple Sugar WHile B Is Starch