Biochem 1- Chapter 12
What term describes molecules that have both hydrophilic and hydrophobic moieties?
amphipathic
glycolipids
carbohydrate containing lipid derived from sphingosine where the carbohydrate is linked to the primary alcohol of sphingosine
phospholipids
include 4 components: fatty acid, a platform, a phosphate, and an alcohol
What is the most common process by which lipids and proteins move in the membrane bilayer?
lateral diffusion
Fatty acids can be saturated or unsaturated
saturated = single bonds unsaturated = double bonds
What important property is conferred on membranes by transport systems?
selective permeability
what ion characteristics move through membranes easiest?
smaller and more polar
What is the number of carbons found in the most commonly observed fatty acids?
16 or 18
name fatty acids for the#C:#double bonds
18:0 is octadecanoic acid (octadecane) 18:1 is octadecenoic acid 18:2 is octadecadienoic acid
How many molecules thick are membranes?
2
Which of the following statements is consistent with the structure of biological membranes
The membrane lipids self-assemble to form the lipid bilayer
) Which of the following membranes would be the most fluid?
a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids
The most common motif found in membrane spanning proteins is
a helices of nonpolar amino acids that pass through the membrane
What substance inhibits prostaglandin H2 synthase-1 by blocking the channel through which the substrate, arachidonate, travels?
acetylsalicylic acid
cholesterol helps maintain fluidity in membranes
acts as a buffer system
cerebrosides
are the simplest glycolipids, containing only one sugar
In addition to phospholipids and glycolipids, which of the following is a major type of membrane lipid?
cholesterol
Which of the following helps regulate membrane fluidity in animals?
cholesterol
when double bonds are present, they are commonly in the -- configuration
cis
What protein polymerizes into a lattice network around a budding membrane?
clathrin
amphipathic molecules
containing hydrophobic and hydrophilic regions
fatty acids in biological systems usually contain _____ number of carbon atoms:
even
What membrane components contain carbohydrates?
glycolipids
2 common platforms in phospholipids
glyercol (phosphoglycerides/phosphoglycerols) and sphingosine
What property is used to determine the probability that a segment of a protein will be found embedded in a membrane?
hydropathy
fatty acids
key constituents of lipids named based on their parent hydrocarbons chains of H-bearing carbon atoms that have a carboxylic acid at one end and a methyl group at the other end
cholesterol
lipid based on a steroid nucleus with the attachment of a fatty acid on one side and hydroxyl group on the other. The hydroxyl group interacts with phospholipid heads
What complex is observed between cholesterol and membrane phospholipids?
lipid raft
Membranes are primarily comprised of
lipids & proteins.
short chain fatty acids have a --- melting temperature than long chain fatty acids with the same saturation
lower
unsaturated fatty acids have a --- melting temperature than saturated fatty acids of the same C chain length
lower
The low incidence of protein or lipid flip-flop in a membrane preserves
membrane asymmetry.
Which of the following membrane-bound organelles is thought to have evolved from bacteria by endosymbosis?
mitochondria
2 different naming systems
one starts as C 2 and 3 are alpha, beta other starts at methyl C as omega
Carbohydrate residues attached to the membrane lipids are almost always
positioned on the extracellular side of the membrane
gangliosides
type of sphingolipids (sphingosine or sphingoid backbone) GLYCOLIPIDS glycosidic linages - no phosphate grou; polar head group is oligosaccharides with one or more *N-acetylneuramanic acid (NANA/stalic acid)* at the terminus this contains a *negative charge* play a role in cell interaction, recognition, and signal transduction
The degree of membrane fluidity in bacteria depends mainly on the percentage of
unsaturated fatty acids.
What force(s) stabilize(s) the lipid bilayers?
van der Waals interactions and electrostatic and hydrogen bonding between the polar heads and surrounding water
