Adaptaions to specific environmental conditions
Variation in lipid compositions among cell membranes
Ability to change the lipid composition in response to temp changes has evolved in organisms that live where
Temperatures may vary
What is a membrane?
- Acollage of different proteins
-embedded in the fluid matrix of the lipid bilayer
What do proteins determine?
most of the membranes specific functions
Peripheral proteins are bound to what?
The surface of the membrane
Integral proteins penetrate
The hydrophobic core.
What are trans membrane proteins?
Integral proteins that span the membrane
The hydrophobic regions of proteins consist of what?
One or more stretches of non polar amino acids, often coiled in alpha helices
What are six major functions of membrane proteins?
-attachment to the cytoskeleton and extracellular matrix (ecm
Cells recognize each other by?
binding to surface molecules
What do surface molecules often contain
carbohydrates on the extracellular surface of the plasma membrane
Membrane carbohydrates may be covalently bonded to?
Lipids (forming glycolipids)
Or More commonly to proteins (forming glycoproteins)
carbohydrates on the external side of the plasma membrane vary among?
species, individuals, and even cell types in an individual