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cell membranes are made of a lipid bilayer, molecules with hydrophilic heads and hydrophobic tails. These molecules arrange in parallel lines with the tails facing inwards towards each other and the heads facing outwards towards the water. Hydrophobic molecules are drawn into the lipid bilayer, trying to get away from the water.
Wiki User
∙ 11y ago
Wiki User
∙ 9y agoSmall hydrophobic substances cross the membrane by diffusion. Larger molecules are transported through aqueous compartments of cells or through extracellular space by water-soluble carriers.
Anonymous
They cross through protein channels. Since they cannot pass the simple diffusion like hydrophobic molecules can, they have to use protein channels. It cannot pass through the cell membrane through diffusion because the barrier of the membrane is hydrophobic. So, they use the proteins attached to the cell membrane to cross through the cell membrane.
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What substances normally fail to cross cell membranes under any circumstances?
Big molecules and charged molecules or atoms.
What is the main reason Na and K ions CANNOT easily diffuse through plasma membranes?
they are hydrophilic and can't cross the hydrophobic region of the plasma membrane
In the digestive process the macromolecules are broken down into small molecules that can cross cell membranes This process is called?
dehydration synthesis
He characteristics that best describe the tail of a phospholipid molecule are .?
The most notable characteristic is amphipathicity, meaning it is hydrophilic on one end and hydrophobic on the other. This allows it to form a bilayer, of which cell membranes are made. If a molecule were to cross through the membrane, it would need to diffuse through a hydrophilic region, a hydrophobic region, and another hydrophilic region, which is difficult for most molecules. This is why the phospholipid bilayer is a good way to separate a cell from its environment.
What kind of substance cannot pass through the cell membrane?
lipids, and ribosomeslipids
What is a factor that determines whether molecules can cross a cell membranes?
mass
What is most likely to occur if the sugar molecules can cross the membranes?
Sugar molecules move outside of the membrane.
What kind of substances do protein channels allow to cross membranes?
Ions and large molecules
What substances normally fail to cross cell membranes under any circumstances?
Big molecules and charged molecules or atoms.
What is the main reason Na and K ions CANNOT easily diffuse through plasma membranes?
they are hydrophilic and can't cross the hydrophobic region of the plasma membrane
What gives water the ability to cross the hydrophobic region of a cell membrane when other small polar molecules and ions cannot?
Bc its fckn water
In the digestive process the macromolecules are broken down into small molecules that can cross cell membranes This process is called?
dehydration synthesis
He characteristics that best describe the tail of a phospholipid molecule are .?
The most notable characteristic is amphipathicity, meaning it is hydrophilic on one end and hydrophobic on the other. This allows it to form a bilayer, of which cell membranes are made. If a molecule were to cross through the membrane, it would need to diffuse through a hydrophilic region, a hydrophobic region, and another hydrophilic region, which is difficult for most molecules. This is why the phospholipid bilayer is a good way to separate a cell from its environment.
Is this question true or false most polar molecules cannot cross cell membranes without the help of certain proteins?
true
What kind of substance cannot pass through the cell membrane?
lipids, and ribosomeslipids
What is the sequence that represents the cross section of a bilayer?
hydrophillic head, hydrophobic tail, hydrophobic tail, hydrophillic head
What materials crossed the membrane and why did they cross?
Materials that can cross the cell membrane include small non-polar molecules like oxygen and carbon dioxide, as well as small polar molecules like water. These molecules can freely pass through the lipid bilayer of the membrane due to their small size and compatibility with the hydrophobic environment of the lipid tails. However, larger molecules and charged ions require specific protein channels or transporters to cross the membrane.
