9th grade science
posted by Miranda .
where are the cell and plasma membranes located
Since this is not my area of expertise, I searched Google under the key words "cell and plasma membranes" to get these possible sources:
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
A landslide may be caused when friction is ______ by moisture
I think what you mean is the cell membrane/plasma membrane of a cell. If so, they are the same thing.
Unlike the cell wall, the plasma membrane is flexible. In a plant cell, the plasma membrane pushes out against the cell wall to keep its shape. It is always immediately against the cell wall.
The plasma membrane's job is to regulate, or control, everything that goes in or out of the cell. The plasma membrane can be thought of as the cell structure that "chooses" what goes in the cell and what doesn't, and what comes out of the cell and what doesn't--much like the doorkeeper of an exclusive area.
The plasma membrane, which is found in all eukaryotic cells, is made of a double layer of phospholipids (fos-foh-lip-ids) and proteins. The phospholipids make up a bilayer with the tails pointing inward, toward each other. Look at the insert that Mr. Speck is pointing at. The round part is called the head of the phospholipid, and the stick-like end is called the tail of the phospholipid. The head is made of glycerol and phosphate. The heads in the double layer are hydrophilic, meaning that they attract water. The tail of a phospholipid is made of fatty acids. The tails in the double layer are hydrophobic, meaning that they repel water. Phospholipids can move horizontally to allow small molecules, such as water, oxygen, and carbon dioxide to enter the cell.
The job of the plasma membrane proteins is to help move large molecules through the phospholipid bilayer or to aid in cell recognition (to help the plasma membrane keep track of and decide what goes in or out). There are two types of membrane proteins: integral proteins and peripheral proteins. Integral proteins are imbedded completely through the membrane (in the middle). Peripheral proteins are attached on either the inner or outer surface of the plasma membrane.