Mr. Excitement (pen-jen)- Cell Membrane structure Flashcards
what is term that defines a bilayer having a polar outer component and nonpolar inner component?
amphipathic
what is a micelle composed of and how is it arranged?
Fatty acid, or single hydrocarbon chains cluster with their polar head groups out and tails towards center
what biochemical structure composes a common bilayer?
phospholipids (they are shaped like cylinders)
what tends to be impermeable to the bilayer?
ionic solutes and large polar solutes
what are the two categories of phospholipids?
Glycerophospholipids
Sphingophospholipids
what is unique about cholesterol?
it is a sterol with a four ring hydrocarbon
what two molecules are covalently bound in a glycolipid?
carbohydrate and a lipid
what type of fatty acid is known to have “kinks” and what is a unique characteristic of that fatty acid?
unsaturated fatty acid. these types of fatty acids contain double bonds between some carbons, which alters there degree of unsaturation in membrane fluidity
the name implies that glycerophospholipids contain a glycerol backbone, but what other structures are essential for the formation of the lipid?
2 fatty acid tails
a phosphate group (PO4)
polar head
the glycerophospholipids are mainly differentiated based on their polar head groups. what are the most common polar head groups that make the phosphatidyl glycerophosolipids different?
ethanolamine, serine and choline
sphingosine has a long hydrocarbon chain that is part of its own structure. but what is unique about the 2nd hydrocarbon tail on sphingosine?
The binding of a fatty acid to the amino group on the sphingosine adds the 2nd hydrocarbon tail common to membrane lipids
in sphingomyelins what two structures tend to bind to the phosphate group?
ethanolamine, choline
how do shingolipids and glycolipids compare?
both contain a sphingosine backbone rather than a glycerol backbone
how do sphingolipids and glycolipids differ?
glycolipids contain sugar lipids instead of phosphate groups.
what makes membrane less permeable to small water soluble molecules and water. and also reduces fluidity?
cholesterol
what compound makes cholesterol weakly amphipathic?
The hydroxyl group makes the cholesterol weakly amphipathic, so it fits in the lipid bilayer in a specific orientation, with it’s –OH group towards the polar head groups of the phospholipids
why does viscosity play an important in affecting the functions inside a membrane?
Viscosity of the membrane can affect the rotation and diffusion of proteins and other bio-molecules within the membrane, thereby affecting the functions of these molecules
what 3 things contribute most to membrane fluidity?
lipid composition (cholesterol packing) and hydrophobic tails (saturated vs. unsaturated) temperature
how do long saturated tail affect fluidity?
membrane will be less fluid due to the increase in hydrophobic interactions between the tails and the surface
what type of hydrophobic tails increase fluidity and why?
Short, unsaturated tails result in less surface area for interaction