No, the rates of absorption and diffusion are not constant for all molecules. They depend on factors like molecular size, charge, solubility, and membrane permeability. Larger molecules, charged molecules, and less lipid-soluble molecules typically have slower rates of absorption and diffusion compared to smaller, uncharged, and lipid-soluble molecules.
Facilitated diffusion requires the presence of membrane channels or transporters to move molecules across the membrane. Osmosis, on the other hand, does not require membrane channels as it involves the passive movement of water molecules through the lipid bilayer of the membrane.
Lipid-soluble substances can easily pass through the cell membrane due to the presence of phospholipids that make up the membrane. These substances can dissolve in the lipid bilayer and diffuse through it, allowing them to enter the cell more readily. In contrast, substances that are not lipid-soluble may require specific transport mechanisms to facilitate their entry into the cell.
the solubility theory of membrane permeability simply describes that a membrane can only be freely permeable to substances that can dissolve in it. this was the most basic theory posed to explain how substances passed through membranes of cells. another way of explaining this is that substances that can freely or passively diffuse across membranes when they have the same chemical or physical properties as the membrane.
Vitamin C is water soluable so the only way it can be transported is by faciliated difficusion using a channel protein. Channel proteins allow polar, watersoluable substances and ions to pass across the cell membrane using faciliated diffusion. Vitamin D is lipid soluble therefore it can pass through using simple diffusion because the phospholipid bilayer lets it pass through down its concentration gradient.
Small or lipid soluble solutes can pass through the cell membrane via simple diffusion. This process occurs without the need for energy or specific transport proteins, as these solutes can move freely through the lipid bilayer of the membrane due to their size or lipid solubility.
simple diffusion
No, the rates of absorption and diffusion are not constant for all molecules. They depend on factors like molecular size, charge, solubility, and membrane permeability. Larger molecules, charged molecules, and less lipid-soluble molecules typically have slower rates of absorption and diffusion compared to smaller, uncharged, and lipid-soluble molecules.
Facilitated diffusion requires the presence of membrane channels or transporters to move molecules across the membrane. Osmosis, on the other hand, does not require membrane channels as it involves the passive movement of water molecules through the lipid bilayer of the membrane.
Lipid-soluble substances can easily pass through the cell membrane due to the presence of phospholipids that make up the membrane. These substances can dissolve in the lipid bilayer and diffuse through it, allowing them to enter the cell more readily. In contrast, substances that are not lipid-soluble may require specific transport mechanisms to facilitate their entry into the cell.
because of lipid insolubility
Facilitated diffusion is a process whereby a substance passes through a membrane with a aid of an intermediary or a facilitator. The facilitator is an integral membrane protein that spans the width of the membrane. The force that drives the molecule from one side of the membrane to the other is the force of diffusion. and Diffusion is the process of movement of a substance from the region of higher concentration to the region of lower concentration so as to spread uniformly. Difference : Facilitated diffusion is when polar or charged molecules cross the cell membrane through a trans membrane channel protein. Diffusion is when small, non-polar molecules cross the cell membrane directly through the lipid bilayer. they can do so as they are hydrophobic and hence can pass through the hydrophobic core of the lipid bilayer. crossing the lipid bilayer is difficult for charged/polar particles as they are hydrophilic and large (as they may have hydration shells due to their charged nature), hence they have to cross through transport proteins.
Facilitated diffusion is a process whereby a substance passes through a membrane with a aid of an intermediary or a facilitator. The facilitator is an integral membrane protein that spans the width of the membrane. The force that drives the molecule from one side of the membrane to the other is the force of diffusion. and Diffusion is the process of movement of a substance from the region of higher concentration to the region of lower concentration so as to spread uniformly. Difference : Facilitated diffusion is when polar or charged molecules cross the cell membrane through a trans membrane channel protein. Diffusion is when small, non-polar molecules cross the cell membrane directly through the lipid bilayer. they can do so as they are hydrophobic and hence can pass through the hydrophobic core of the lipid bilayer. crossing the lipid bilayer is difficult for charged/polar particles as they are hydrophilic and large (as they may have hydration shells due to their charged nature), hence they have to cross through transport proteins.
the solubility theory of membrane permeability simply describes that a membrane can only be freely permeable to substances that can dissolve in it. this was the most basic theory posed to explain how substances passed through membranes of cells. another way of explaining this is that substances that can freely or passively diffuse across membranes when they have the same chemical or physical properties as the membrane.
Lipid solubility determines if it will diffuse across. The presence of specific protein carrier molecules determines if it will be transported across the membrane.
Certain substances, such as small molecules and ions, are able to cross the cell membrane. The ability of a substance to cross the membrane is determined by its size, charge, and solubility in the lipid bilayer of the membrane.
Vitamin C is water soluable so the only way it can be transported is by faciliated difficusion using a channel protein. Channel proteins allow polar, watersoluable substances and ions to pass across the cell membrane using faciliated diffusion. Vitamin D is lipid soluble therefore it can pass through using simple diffusion because the phospholipid bilayer lets it pass through down its concentration gradient.