BB451 exam 1 - Lipids and Cell Membranes Flashcards
lipids always have at least…
1 part that is very non polar
lipid bilayer
nonpolar tails inside, polar heads outside
form structure by themselves when in water
move across bilayer easily …
water, oxygen, CO2, CO
non-polar tails contain just
C and H
saturated
no double bonds
saturated fatty acids –> atherosclerosis
unsaturated
1 or more double bonds
polyunsaturated = more than 1
double bonds usually in cis configuration
trans fat
double bond in trans configuration
not natural, result of chemical treatment
polar heads have …
ionized carboxyl group
omega #ing
start at methyl end, count towards double bond
delta #ing
start at carboxyl end, count towards double bond
common in biochem
essential fatty acids
can’t make, need in diet
delta >9
ex: linoleic and linolenic
fat structure
glycerol with 3 fatty acids
glycerophospholipid structure
glycerol with 2 fatty acids, a phosphate group
2 main categories of molecules in membranes
glycerophospholipids/ phosphoglycerides
sphingolipids
phosphatidate/ phosphatidic acid
simplest glycerophospholipid
branch point for synthesis of glycerophospholipids and fats
attach new things to phosphate on phosphatidic acid –>
new glycerophospholipids
general name: phosphatidyl -X
most sphingolipids don’t have
phosphate
fatty acid attached to amine –>
sphingolipid
looks like sphingosine because has amine
sphingolipids have 2 __
fatty acids
important b.c. structural restriction for what can fit in bilayer
sphingolipids found more often in…
nerve and brain tissue
ex: sphingomyelin
attachment of sugars to sphingolipids
single sugar –> cerebroside
complex sugars –> ganglioside
steroids
lipids derived from cholesterol
not derived from fatty acids
cholesterol
important for membrane stability
prominent in brain membranes (14% of dry weight of brain)
microbes that live in hydrothermal vents have..
different lipid in membranes: ether lipids (instead of ester bonds)
fatty acids in water –>
micelle: tails point into circle, heads point out
ex: soap, central nonpolar sticks to grease
liposome
artificial lipid bilayer (used in labs)
donut shaped, water in middle, looks like cell
mix glverophospholipids and sphingolipids in water –> spontaneously form structure
liposomes useful for
to fuse with cell and deliver certain substances into cell, when not easily transported across membrane
4 types of membrane proteins
integral - across both layers, difficult to remove
peripheral - into only 1 side of membrane, easy to remove
anchored - linked to a molecule (fatty acid) embedded in bilayer
associated - associates with membrane by H-bonding with an integral protein, easy to remove
bacteriorhodopsin
integral membrane protein
used light, chemistry, and mechanics to move proteins across a membrane
found in bacteria that are photosynthetic
vitamin A allows use of light
trans cis kicks protons out
membrane spanning proteins have __
non polar membrane crossing regions
polar short sections
(can use computer to predict aa sequence and if it’s a membrane protein)
prostaglandins
arise from arachadonic acid by prostaglandin synthase (COX enzyme, peripheral protein)
associated with pain, inflammation and uterine contraction
prostaglandin synthesis inhibited by
NSAIDs (inhibit cox enzymes)
Asprin and stomach problems
some prostaglandins necessary for synthesis of intestinal tissue (COX 1), NSAIDs can cause stomach issues
tried to inhibit just cox 2 in joints…
ex: vioxx, Celebrex
recall for side effect of damaging heart tissue
___ retain fluidity at lower temps
shorter, more unsaturated fatty acids
ex: fish membranes - unsaturated and polyunsaturated
___ not as fluid
longer, saturated fatty acids
fluid mosaic model
things moving in membrane very fast
use laser to bleach cell in specific place, watch how long it takes to for color to disappear
lateral diffusion
rapid
transverse diffusion
flip-flop
very slow
flipase catalyzes (fact that we have flipases = arrangement is important)
Tm
midpoint of conversion between solid and fluid state
* a temperature
(midpoint of steep part of curve between flat states)
cholesterol and Tm
cholesterol does not change Tm
widens the range of the transition temps between solid and fluid
Sodium Potassium ATPase
integral membrane protein that performs active transport
*3 Na out, 2 K in
movement essential to maintain osmotic balance
antiport
used to drive other pumps
Na/K ATPase is ___ transport mechanism…
electrogenic transport mechanism
bacterial membranes
have layers and covalent bonds
different aa’s in D configuration (cant be attacked by proteases)
receptor mediated endocytosis
ex: cholesterol enters via LDLs that attach to receptors on cell’s surface
entire LDL with cholesterol taken into cell
