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If by why you mean how, then the answer lies in the fact that cell membranes have special transport channels for different materials. Essentially, the phospholipid bilayer means that the outside of the cell membrane is charged (polar) and the inside is uncharged (non-polar). Whilst uncharged molecules can easily squeeze in between the phospholipids, the charged molecules have a problem. Because they carry a charge it means that they cannot enter the area in the middle where there is no charge, so there are special protein channels. These channels are lined with charge and allow the passage of polar (charged) molecules through the cell membrane.
Wiki User
∙ 12y ago
Wiki User
∙ 13y agoNon polar molecules can pass through easily since the middle part of cell is hydrophobic as well. However, the size of this non polar molecule has to be relatively small to fit in between the pores (between the phospholips). If bigger, they must use other methods like protein channels.
It is much harder for polar molecules to pass through since the middle part is hydrophobic. However, polar molecules like water can pass through since they go through extremely fast and because they are extremely SMALL molecules. Bigger ones have no chance of going through phospholipds.
Wiki User
∙ 13y agoBecause the plasma membrane has a hydrophobic inner layer.
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Why do most substances have to be assisted through the plasma membrane?
The plasma membrane is made from tightlypack phospholipids. The plasma membrane prevents polar molecules and large molecules from diffusing freely. Fatty (lipophilic) molecules can easily pass through. since cells often need water soluble materials such as water and sugars, transporters and pores need to be made out of proteins to let those molecules through. One of the most important pumps is the Na+/K+ ATPase pump which maintains gradients of sodium and potassium across the cell membrane
How much glycoproteins are in the cell membrane?
there are 2% of the molecules in plasma membrane and 50% of its weight these are the protins in the animal cells.
Is the cytoskeleton in the plasma membrane?
No. It is attached to the plasma membrane though, which is important. The cytoskeleton gives cells shape and rigidity etc and so it is important for it to be attached to the plasma membrane. The cytoskeleton is composed of molecules that are located in the cytoplasm but that are attached to the plasma membrane via specific proteins. Hope that helps!
The cell membrane also is called the?
The cell membrane is also known as the plasma membrane or the cytoplasmic membrane. It is a biological membrane that separates all cells' interior from the outside, though can be permeated by selection ions and molecules. Its basic function is to protect the cell from its surroundings.
Does prokaryotic or eukaryotic cells contains plasma membrane?
Both eukaryotic cells and prokaryotic cells have a plasma membrane.
Which structure regulates passage of molecules into and out of cells?
The cell membrane is a membrane separating the inside of the cell from the outside environment. This structure is also known as the plasma membrane or the cytoplasmic membrane.
What are chemical messengers that pass through the plasma membrane of cells and have receptor molecules in the cytoplasm?
mitochondria
Why do most substances have to be assisted through the plasma membrane?
The plasma membrane is made from tightlypack phospholipids. The plasma membrane prevents polar molecules and large molecules from diffusing freely. Fatty (lipophilic) molecules can easily pass through. since cells often need water soluble materials such as water and sugars, transporters and pores need to be made out of proteins to let those molecules through. One of the most important pumps is the Na+/K+ ATPase pump which maintains gradients of sodium and potassium across the cell membrane
Which cell or cells have a plasma membrane?
ALL CELLS HAVE a plasma membrane
How do some molecules get into cells?
Some molecules get into cells by going through their permeable membrane.
How much glycoproteins are in the cell membrane?
there are 2% of the molecules in plasma membrane and 50% of its weight these are the protins in the animal cells.
Is the cytoskeleton in the plasma membrane?
No. It is attached to the plasma membrane though, which is important. The cytoskeleton gives cells shape and rigidity etc and so it is important for it to be attached to the plasma membrane. The cytoskeleton is composed of molecules that are located in the cytoplasm but that are attached to the plasma membrane via specific proteins. Hope that helps!
How do glucose molecules cross a plasma membrane on the apical side of epithelial cells?
secondary active transport
The cell membrane also is called the?
The cell membrane is also known as the plasma membrane or the cytoplasmic membrane. It is a biological membrane that separates all cells' interior from the outside, though can be permeated by selection ions and molecules. Its basic function is to protect the cell from its surroundings.
Does prokaryotic or eukaryotic cells contains plasma membrane?
Both eukaryotic cells and prokaryotic cells have a plasma membrane.
Do plant and animal cells have a plasma membrane?
do animal have a plasma membrane
How does osmosis occur in cells?
Osmosis is the process of movement of water molecules from its higher conc. to its lower conc. through a semi permeable membrane. In cells ,the plasma membrane is a selectively permeable membrane, when a cell is placed in a hypotonic medium, water travels into the cell referred to as endosmossis. similarly when water molecules moves out, it is termed as exosmosis.
