Mebrane Structure (2.2) Flashcards
Describe the structure and properties of phospholipids
Phospholipids consist of a hydrophilic phosphate head with two hydrophobic fatty acid tails. They are also anchor proteins within the membrane
Explain why phospholipids form a bilayer in cell membranes
Because their fatty acid tails are poorly soluble in water, phospholipids spontaneously form bilayers in aqueous solutions, with the hydrophobic tails buried in the interior of the membrane and the polar head groups exposed on both sides, in contact with water
List the other components of cell membranes and give a function for each
Peripheral membrane proteins are exterior to and connected to the membrane by interactions with other proteins. Integral membrane proteins are inserted into the membrane and most pass through the membrane. Portions of these transmembrane proteins are exposed on both sides of the membrane. Cell membrane proteins have a number of different functions.
Structural proteins help to give the cell support and shape.
Cell membrane receptor proteins help cells communicate with their external environment through the use of hormones, neurotransmitters, and other signaling molecules.
Transport proteins, such as globular proteins, transport molecules across cell membranes through facilitated diffusion.
Glycoproteins have a carbohydrate chain attached to them. They are embedded in the cell membrane and help in cell to cell communications and molecule transport across the membrane.
Explain why the cell membrane is called a fluid mosaic
It is called a fluid mosaic model as within the membrane there is a pattern of different types of molecules distributed across the membrane (mosaic) and these molecules move around in a fluid fashion (fluid)
Explain how the level of cholesterol affects membrane fluidity
Without cholesterol, the phospholipids in your cells will start to get closer together when exposed to cold, making it more difficult for small molecules, like gases to squeeze in between the phospholipids like they normally do. Without cholesterol, the phospholipids start to separate from each other, leaving large gaps.
Explain how saturated and unsaturated phospholipid tails affects membrane fluidity
These kinks (unsaturated) play a role in membrane fluidity because they increase the space between the phospholipids, making the molecules harder to freeze at lower temperatures. In addition, the increased space allows certain small molecules, such as CO2 and O2, to cross the membrane quickly and easily.
