By Passive transport i can onlythink of glucose, but by active transport material like water, carbon dioxide, amino acids, sodium and potasium and of course oxygen! :)
small and nonpolar.
Hydrophobic
Facilitated diffusion is the process in which a membrane protein helps (facilitates) a substance pass through the bilayer. For example, water is too big a molecule to passively diffuse through the phospholipid bilayer and does not need to be actively imported. So the solution to this, is to put a transmembrane protein in the bilayer to form a channel big enough for the water molecule to pass through. I don't know how much you need to know, but just as a side note, the channel protein will be in its secondary structure, either as a beta sheet or alpha helix. I hope that helps.
In hot water molecule were moving around faster so substances diffuse faster than in cold water.
Yes, hydrogen diffuses faster than methane. The hydrogen molecule, H2, is the smallest of all molecules and it is considerably smaller than the methane molecule, CH4. Smaller molecules move faster, and therefore diffuse faster, at any given temperature, than larger molecules.
why does Co2 diffuse faster than So2
All gases diffuse to a homogenous phase.
an ion
Hydrophobic centre of the phospholipid bilayer prevents non-liquid soluble molecules from passing through.
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.
Glucose does not readily diffuse across a lipid bilayer. In order for glucose to travel into the cell, it needs the help of a transport protein. This is called a facilitated diffusion.
Ions cannot diffuse through a phospholipid bilayer because they are not able to dissolve in lipids, hence the phosphoLIPID bilayer . Also, since they have an electrical charge, they are repelled by the membrane.
Salts are soluble. The phospholipid bilayer membrane of cell walls are permeable to water and thus allow water and water-soluble substances, like salts, diffuse through.
Facilitated diffusion is the process in which a membrane protein helps (facilitates) a substance pass through the bilayer. For example, water is too big a molecule to passively diffuse through the phospholipid bilayer and does not need to be actively imported. So the solution to this, is to put a transmembrane protein in the bilayer to form a channel big enough for the water molecule to pass through. I don't know how much you need to know, but just as a side note, the channel protein will be in its secondary structure, either as a beta sheet or alpha helix. I hope that helps.
molecules that can survive the hydrophobic interior of the lipid bilayer
Water cannot diffuse a plasma membrane because of the fact that the phosphate heads of the phospholipids are hydrophilic, the hydrocarbon tails of the phospholipids are hydrophobic, meaning they repel water. The bilayer phospholipid model of the plasma membrane shows that the phophates face outward on either side of the membrane and the lipid tails are in the middle of the bilayer.
The structure of cell membrane allows nonpolar molecules to diffuse, but not polar molecules. Membrane architecture is in the form of a phospholipid bilayer. A single phospholipid has a "head" composed of a polar NH3 group, and two "tails" composed of nonpolar fatty acids. The lipids spontaneously arrange themselves into bilayers with the hydrophilic heads directed outward, and the hydrophobic tails facing inward. Because nonpolar solvents can only dissolve nonpolar solutes, polar molecules cannot mix with the nonpolar inside of the lipid bilayer. A polar molecule cannot cross the cell's lipid membrane without aid from a carrier protein. While this is true, there are multiple forces that dictate whether or not a molecule can cross a phospholipid membrane, including electrochemical gradients and size. Very small and non-polar molecules have a very easy time crossing the phospholipid bilayer. However, very small, polar molecules like water can also cross the phospholipid bilayer due to hydrostatic pressure and concentration gradient differences. Water will, but with some difficulty because of it's polarity. Aquaporins, protein channels embedded into cellular membranes allow for sufficient amounts of water to diffuse into cells.
Because there is a hydrophobic core in the phospholipid bilayer, it may be difficult for water molecules to pass through the membrane. Therefore, there are proteins that aid this process called aquaporins.
Nonpolar molecules like lipid-soluble substances (e.g., steroid hormones, oxygen, and carbon dioxide) are most likely to passively diffuse across the plasma membrane by dissolving in the lipid bilayer. This type of diffusion does not require a specific transport protein and can occur directly through the phospholipid bilayer due to the molecules' hydrophobic nature.