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What you are referring to is the lipid bilayer, which is basically the cell membrane. Animal cells have this so that they can control what enters and leaves the cell. (This is called being selectively permeable) This helps the animal cell maintain homeostasis, which is controlling your insides despite outside conditions.
What else can I help you with?
What kind of lipid make up the bilayer that form cell membrane?
Phospholipids, where one end is hydrophobic and the other is hydrophilic.
A Phospholipid molecule has a head and the two tails are found where?
The head of a phospholipid molecule is hydrophilic, meaning it is attracted to water, and is found on the outside of the lipid bilayer. The two tails are hydrophobic, meaning they repel water, and are located on the inside of the lipid bilayer.
How does the structure of the plasma membrane allow materials to move across it in both directions?
The structure of the plasma membrane consists of the phospholipid bilayer, which gives it a fluid structure, and not rigid, allowing the materials ease to pass through. Next, there are also integral proteins which can be thought of as 'tunnels', allowing the materials to come in and out. Then, there are peripheral proteins which also aid in getting the materials inside an out. On the cell membrane, there are receptors which recognize outside materials, and if they are really big, the cell engulfs these molecules through endocytosis [pinocytosis, and phagocytosis, which are basically for liquid molecules, and solid molecules]. This takes us back to the fluidity of the cell membrane. That's roughly how the cell membrane allows for the entering and exiting materials.
Can polar molecules and molecules that have chargers sneak through the nonpolar middle portion of the phospholipid bilayer?
Polar molecules and charged molecules generally cannot easily pass through the nonpolar middle portion of the phospholipid bilayer due to the hydrophobic nature of this region. Instead, they are typically transported across the membrane by specific transport proteins such as channels or carriers.
Can water move through the middle of a membrane?
Yes, water can move through the middle of a membrane through a process called osmosis.
Which part of a phospholipid molecule is found in the middle of a lipid bilayer?
The hydrophobic tails of the phospholipid molecule are found in the middle of a lipid bilayer. These tails are composed of fatty acid chains that are repelled by water and therefore are oriented towards the interior of the membrane to avoid contact with the surrounding water.
When a membrane is freeze fractured the bilayer splits down the middle between the two layers of phospholipids In the electron micrograph of a freeze-fractured membrane the bumps seen on the fracture?
Integral Proteins.
Why would a substance not be able to pass through a membrane by diffusion?
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.
What kind of lipids make up the bilayer that forms the cell membrane?
Phospholipids
Why are fat soluble molecules the only molecules that permeate across a cell membrane?
Because small non polar molecules are the ones able to cross due to the fact that the membrane consists of a phospholipid bilayer where the middle is composed on non polar tails
What kind of lipid make up the bilayer that form cell membrane?
Phospholipids, where one end is hydrophobic and the other is hydrophilic.
Where is cholesterol found in cell membrane?
The plasma membrane is present in all prokaryotic and eukaryotic cells. It is the semi-permeable membrane that encloses the cell. So to clearly answer your question, the plasma membrane is found on the outside of the cell; it encircles the cell.
Cell membranes are made up of what?
Cell membranes are primarily composed of phospholipids, proteins, cholesterol, and carbohydrates. The phospholipids form a bilayer, with hydrophobic tails facing inward and hydrophilic heads facing outward. Proteins embedded in the membrane provide structure and function, while cholesterol helps maintain membrane fluidity. Carbohydrates on the outer surface are involved in cell recognition and communication.
What is the composition of plasma membrane?
there are four main parts of the plasma membrane of a cell. 1) the lipid bilayer: this is made up of amphipathic molecules, with the polar heads on the outsides and the non polar tails in the middle. this part is semi-permeable. 2) the proteins: these work as canals to pump larger molecules through the bilayer which couldn't otherwise fit. 3) the carbohydrates: these are different on each cell and are used as the "chemical id tag" for identifying other cells. 4) the cholesterol: this is used to keep the lipid bilayer as plasma instead of turning into a solid. hope this helps (:
A Phospholipid molecule has a head and the two tails are found where?
The head of a phospholipid molecule is hydrophilic, meaning it is attracted to water, and is found on the outside of the lipid bilayer. The two tails are hydrophobic, meaning they repel water, and are located on the inside of the lipid bilayer.
How do water soluble molecules enter or exit a cell?
Water molecules move by osmosis through the cell membrane which is a selectively permeable membrane. Since the middle of the lipid bilayer is hydrophobic, the movement of water is made possible by water channels or aquaporins in the membrane.
How are proteins positioned within the membrane?
The protein is anchored into the membrane by its nonpolar region, but the protein remains moblie. To explain it more, the middle section of the protein is made of many nonpolar amino acids. This nonpolar coil fits into the nonpolar interior of the lipid bilayer allowing the protein to float in the membrane.
