Phosphate groups
The cell membrane is made out of two layers , a nonpolar and polar part. The polar part is the hydrophilic part , meaning water loving , and the nonpolar is hydrophobic part - water hating. The polar/hydrophilic part is inside of the membrane and the outer portion is the hydrophobic/nonpolar . You don't want the cell to exist in water or be soluble in water because then we would dissolve , all our cells , tissues etc. That's why the cell membranes outer portion is nonpolar and is not miscible with water . The cell membrane allows water molecules to come in and out of the cell by osmosis , and that is when water molecules can free out and in of the cell through the cell membrane .
The cell membrane is mostly composed of phospholipid molecules. Each of these has a polar head and a non-polar tail part. The polar bits are attracted to water (hydrophilic) , and the non-polar parts repel water (hydrophobic). In the membrane, they form a double layer - like a sandwich - the polar heads stick out, and the tails form the middle, like the filling inside the sandwich. This way, the inner and the outer surfaces of the membrane are hydrophilic, being on "good terms" with the water in the outer environment and the water in the cytoplasm. At the same time, the membrane separates these two aqueous environments from each other - exactly because there is a non-polar middle layer, that does not allow polar substances to cross to the other side.
Small hydrophobic molecules can cross the cell membrane easily because the membrane is made up of a lipid bilayer that repels water but allows non-polar molecules, like hydrophobic ones, to pass through.
The hydrophilic heads of phospholipids in the cell membrane attract water molecules. These heads have a charge that interacts with the polar water molecules, allowing them to form hydrogen bonds with the water. This hydrophilic property helps create a stable structure for the cell membrane.
It depends on what type of selectively permeable membrane. The cell membrane, which is an example of a selectively permeable membrane, allows the passage of non-polar molecules (such as steroid hormones) and small uncharged polar molecules (such as water).
Phosphate groups
Phosphate groups
Phosphate groups
phosphate groups
Phosphate groups
Phosphate groups
phosphate groups
phosphate groups
The cell membrane is made out of two layers , a nonpolar and polar part. The polar part is the hydrophilic part , meaning water loving , and the nonpolar is hydrophobic part - water hating. The polar/hydrophilic part is inside of the membrane and the outer portion is the hydrophobic/nonpolar . You don't want the cell to exist in water or be soluble in water because then we would dissolve , all our cells , tissues etc. That's why the cell membranes outer portion is nonpolar and is not miscible with water . The cell membrane allows water molecules to come in and out of the cell by osmosis , and that is when water molecules can free out and in of the cell through the cell membrane .
The polarity of water molecules, due to their unequal distribution of charge, allows them to form hydrogen bonds with the polar head groups of phospholipids in the cell membrane. This attraction helps water molecules adhere to the membrane and interact with the hydrophilic regions of phospholipids. Additionally, the small size of water molecules enables them to move freely through the cell membrane.
Usually Ions and charged molecules (salts dissolved in water), large polar molecules (glucose), and macromolecules.
The cell membrane is mostly composed of phospholipid molecules. Each of these has a polar head and a non-polar tail part. The polar bits are attracted to water (hydrophilic) , and the non-polar parts repel water (hydrophobic). In the membrane, they form a double layer - like a sandwich - the polar heads stick out, and the tails form the middle, like the filling inside the sandwich. This way, the inner and the outer surfaces of the membrane are hydrophilic, being on "good terms" with the water in the outer environment and the water in the cytoplasm. At the same time, the membrane separates these two aqueous environments from each other - exactly because there is a non-polar middle layer, that does not allow polar substances to cross to the other side.