Chapter 8 Flashcards
Shorter fatty acids had (higher/lower) melting point
Lower
Saturated fatty acid examples
No DB
Palmitate and Stearate
Which glycophospholipids have H-bonding head groups?
All except phosphatidylcholine
Why are archaeal lipids more stable than glycerophospholipids?
Acyl attached by ether linkage (not ester)
Why do antibiotics decrease vitamin K?
50% made by bacteria
Melting points of fatty acids
Double bonds: more important
More DB = low mp
Length: shorter = lower mp
Animal fatty acids are solids because they are
Longer, more saturated
Does cholesterol promote crystallization or fluidity?
Neither
Decreases fluidity (movement of acyl)
Decreases crystallization (preventing close packing of groups)
Why can steroids be intracellular proteins?
They are nonpolar and pass through the bilateral
Why do glycerosphingolipids pack loosely?
They have larger head groups.
Are lipid rafts more or less fluid than the membrane? Why?
Less fluid
Why? –>
- Presence of cholesterol
- Saturated acyl chains
Locations of glycerophospholipids (Hint: based on head groups)
Ethanolamine and serine: Inner leaflet
Choline- outer leaflet
Glycerol- both leaflets
What phospholipases cleave what stuff?
A1/A2: Acyl Chains
C: phosphate derivative
D: Polar Group
Fatty Acids
not free in cell, too disruptive
form micelles
Even numbered C chains
Triglycerides
Functions structure
Storage for fuel
Hormone signaling
Glycerol + 3 fatty acyl chains
Ester bond
Adipose Tissue globules
Glycerophospholipids
Glycerol + 2 fatty acyl chains +
1x phosphate derivative (head group)
Ester bond
Sphingolipids:
Backbone of serine and palmitate
Amide Bond - attaches 2nd fatty acyl group to serine nitrogen
Sphingomyelins head groups
phosphocholine or phosphoethanolamine
Glycolipids head groups
Cerebroside- monosaccharide
Ganglioside- oligosaccharide head group
In a glycerophospholipids, ____esterified at position 1 and 2, ___ at position 3
Acyl groups
Phosphate
How do omega 3:6 ratio for inflammation work?
Compete for enzymes that convert fatty acids to signaling molecules.
Archaeal membrane differences:
Glycerol has opposite chirality
Acyl chains on C2 and C3
Tails are branched, not straight
Hydrocarbon tails attached by ETHER bond, not ester. (harder to degrade)
Name some isoprenoids
Ubiquinone
Cholesterol
tails of archaeal membrane lipids
Vitamins
Waxes
Protect plants from water loss
Alcohol + Fatty acids
Vitamin A
Vision- too little = blind, too much= birth defects
From beta-carotene
Retinol oxidized to retinal, aldehyde with is light receptor in the eye
Vitamin D
Too little: Rickets (stunt growth, deformed bones)
Too much: Abnormal calcification of tissues
D2- plants
D3- cholesterol
UV light by liver and kidneys
Calcium deposits in bones and teeth
Vitamin E
Alpha-tocopherol
Hydrophobic molecule in cell membranes Immune function (antioxidant)
Deficiency: membrane damage
Vitamin K
1/2 by intestinal bacteria, rest from green plants
carboxylation of glutamate residues in proteins involved in BLOOD CLOTTING.
Poor coagulation: prevents Glu carboxylation, inhibits normal protein function, excessive bleeding
What CAN make the bilayer?
Glycerophospholipids
Sphingolipids
Why can’t these make the bilayer:
Fatty acids
Triacylglycerols
Pure Cholesterol
Fatty acids? Form spheres
Tri? no, almost completely NP
Cholesterol? no, only single polar hydroxyl group
Rafts
Near Crystalline
Tight Cholesterol and Spingolipids
Important for signaling: can anchor proteins
What causes lipid asymmetry?
Orientation of lipid synthesizing enzymes in ER.
Alpha Helix
20 to transverse
hydrophobic in middle, larger chains
Charged residues: where it’s exposed to solvent
Beta barrel
interior hydrophilic, exterior phobic
side chains in beta sheet point alternately to each face, so some point to interior, others to bilayer → thus, can’t predict form primary sequence
Some large ones have central water whole
Smallest are about 8 strands
The alpha helix and beta barrel are subtypes of
integral membrane proteins
Where do most lipid-linked proteins face?
interior
The one weird long named lipid linked protein thing.
almost always face external surface of cell, found in sphingolipid- cholesterol rafts
C-terminus attached to sugar chain
lipid-carbohydrate group (attach phosphotal and oxitial groups)
Getting those pesky proteins out the membrane: How to
Peripheral: Easy, some salt
Integral: detergent, destroy the whole membrane
lipid-linked: salt usually works
Do membrane proteins move?
laterally only
Do membrane proteins diffuse freely?
No, interactions with cytoskeletal elements
