Chapter 7: Membrane Structure and Function Flashcards
Two types of cellular membrane proteins
Integral (transmembrane)
Peripheral (does not go through the bilayer
Amphipathic molecules?
Hydrophobic and hydrophilic components
Describe the movement of phospholipids across the membrane
Phospholipids in the plasma membrane can mice within the bilayer
Most lipids and some proteins drift laterally
Rarely do they flip flop transversely across the membrane
Do proteins move in the membrane?
Some drift within the bilayer
Move slower than lipids
Some moved by motor proteins in the cytoskeleton
Some never move and are anchored by The cytoskeleton
Cholesterol regulates the ___________ of a membrane
Fluidity
Cholesterol wedges between plasma membrane of animal cells
Two types of membrane proteins
Peripheral proteins- loosely bound, cytoplasmic side and exterior side
Integral proteins- within the membrane
Proteins that have a hydrophobic and hydrophilic regions, transmembrane proteins
Integral proteins
Covalent attachments of a lipid to an amino acid side chain within a protein
Lipid-anchored proteins
Six major functions of membrane proteins??
- transport
- enzymatic activity (speed up chemical reactions)
- signal transduction
- Cell-cell recognition
- intercellular joining
- attachment to the cytoskeleton and extracellular matrix (ECM)
Cells recognize each other by binding to surface molecules, often ___________, on the plasma membrane
Carbohydrates
Also glycolipids, glycoproteins, usually branched oligosaccharides with fewer than 15 sugar units
The asymmetrical distribution of proteins, lipids and associated carbohydrates in the plasma membrane is determined when the membrane is built by the _________________
ER and Golgi apparatus
What can pass through the plasma membrane rapidly, dissolve in the lipid bilayer?
Hydrophobic (nonpolar) molecules and gasses
What does not pass through the plasma membrane easily? Mostly transported through transport proteins
Hydrophilic/ polar molecules
What diffuses slowly across the PM?
Ions
Water enters through the plasma membrane though….
Aquaporins
What allows the passage of hydrophilic substances or certain ions across the membrane?
Transport proteins