Plasma Membrane and Fluid Mosaic Model

Flashcards covering the structure and function of the plasma membrane, phospholipids, peripheral and integral proteins, and the fluid mosaic model.

What basic functions does the cell membrane provide for a cell?

It provides a boundary between the interior of the cell and the outside environment, allowing cells to establish internal environments and controlling the transport of materials in and out of the cell.

Why are phospholipids described as amphipathic?

Phospholipids are amphipathic because they contain both hydrophilic (water-attracting) and hydrophobic (water-avoiding) regions.

How do the chemical properties of a phospholipid's head and tail differ?

The phosphate head is polar and hydrophilic (attracted to water molecules), whereas the fatty acid tail is non-polar and hydrophobic (avoids water).

How do phospholipids spontaneously arrange in an aqueous environment?

They form a bilayer where the hydrophobic fatty acid tails are located inside the bilayer and the hydrophilic heads are exposed to the aqueous outside and aqueous inside environments.

What are peripheral membrane proteins and what are their characteristic properties?

Peripheral proteins are loosely bound to the surface of the membrane and are hydrophilic with charged and polar side groups.

What are integral proteins and transmembrane proteins?

Integral proteins span the membrane with hydrophobic nonpolar side groups penetrating the interior and polar hydrophilic side groups. Transmembrane proteins are specific integral proteins that cross the entire membrane.

What six major functions do embedded membrane proteins play?

1. Transport
2. Cell-cell recognition
3. Enzymatic activity
4. Signal transduction
5. Intercellular joining
6. Attachment for extracellular matrix of cytoskeleton

How does the Fluid Mosaic Model describe the structure and mobility of the cell membrane?

It describes the membrane as a mosaic of protein molecules in a fluid bilayer of phospholipids. The structure is not static, allowing most lipids and some proteins to shift and flow along the surface or across the bilayer.

What holds the structure of the fluid mosaic model together?

It is held together primarily by hydrophobic interactions, which are weaker than covalent bonds.

What is the role of cholesterol in eukaryotic cell membranes?

Cholesterol, a type of steroid randomly distributed and wedged between phospholipids, regulates membrane bilayer fluidity under different environmental conditions.

What is the distinction between a glycoprotein and a glycolipid?

A glycoprotein is one or more carbohydrates attached to a membrane protein, whereas a glycolipid is a lipid with one or more carbohydrates attached.

How do carbohydrates and lipids in the cell membrane function as markers?

Their diversity and location on the membrane enable them to function as markers.