Chapter 7 Flashcards
Aquaporin
A membrane protein that enables water molecules to pass through the membrane.
Amphipathic
Has both a hydrophilic region and a hydrophobic region
Fluid mosaic model
The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
A membrane is held together primarily by ____
Hydrophobic interactions
The membrane remains fluid to a lower temperature if it is rich in phospholipids with ….
Unsaturated hydrocarbon tails.
Cholesterol can be thought of as a…
Fluidity buffer for the membrane because it resists changes in membrane fluidity that can be caused by changes in the temperature.
Like a tile mosaic, a membrane is…
A collage of different proteins, often clustered together in groups, embedded in the fluid matrix of the lipid bilayer.
Proteins determine most of the membrane’s functions.
True
Integral proteins
Penetrate the hydrophobic interior of the lipid bilayer. Transmembrane proteins span through the entire membrane.
The hydrophobic interior of an integral protein consists of…
Non polar amino acids usually coiled into alpha helices
Peripheral proteins
Are not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins.
Six major functions performed by proteins of the plasma membrane
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and ECM
How membrane sidedness arises:
The asymmetrical arrangement of proteins, lipids, and their associated carbohydrates in the plasma membrane is determined as the membrane is being built by the ER and Golgi apparatus.
What molecules can cross the lipid bilayer of the membrane easily?
Non-polar, hydrophobic, molecules
The hydrophobic interior of the membrane impedes direct passage through the membrane of….
Ions and polar molecules, which are hydrophilic
Channel proteins
-Transport proteins
Have a hydrophilic channel
Ex. Aquaporins
Carrier proteins
-Transport protein
Hold onto their passengers and change shape in a way that shuttles them across the membrane.
The concentration gradient itself represents ___________ and drives diffusion
Potential energy