CHP 5 (INC) Flashcards
What is the plasma membrane composed of?
A thin layer of lipids and proteins, it separates the cell from its surroundings
Why is the plasma membrane important?
In order to maintain the internal environment, cells of all organisms must constantly exchange molecules and ions with the fluid environment that surrounds them.
What do transport proteins do?
They move particular ions and molecules, including water in a directed way across the membrane
What is the biological membrane consisted of?
Lipids and proteins assembled into a thin film, this membrane separates the aqueous solution outside the cell from the aqueous solution inside the cell.
What are the two major types of lipids in membranes?
Phospholipids and sterols.
What are phospholipids composed of within the phosphate group
A polar (electrically charged end) with a nonpolar (uncharged end) containing two nonpolar fatty acid tails. The polar end is hydrophilic and the nonpolar end in hydrophobic.
Name a few characteristics of the phospholipid Bilayer
In a bilayer the polar ends of the phospholipid molecules are located that the surfaces facing the aqueous media. The nonpolar fatty acid chains assemble in the membrane interior in a nonpolar region that excludes water. At low temperatures the phospholipid bilayer freezes into a semisolid gel like state. When a phospholipid bilayer is shaken in water, it breaks and spontaneously forms small vesicles.
What is the structure of a sterol?
A nonpolar carbon ring with a nonpolar side chain at one end and a single polar group (–OH) at the other end
What is the main sterol in animal membranes?
Cholesterol, it is important for keeping the membranes fluid.
What do recognition proteins do?
They identify a cell as part of the same individual or as foreign
What do receptor proteins do?
Recognize and bind molecules from other cells that act as chemical signals, such as hormones.
What do cell adhesion proteins do?
They bind cells together by recognizing and binding receptors or chemical group on other cells.
Where are glycolipids and glycoproteins found?
They are found on the outer surface of cell membranes. They form a surface coat called the glycocalyx.
