BB451 exam 1 - Lipids and Cell Membranes

Question 1

lipids always have at least…

Answer 1

1 part that is very non polar

Question 2

lipid bilayer

Answer 2

nonpolar tails inside, polar heads outside

form structure by themselves when in water

Question 3

move across bilayer easily …

Answer 3

water, oxygen, CO2, CO

Question 4

non-polar tails contain just

Answer 4

C and H

Question 5

saturated

Answer 5

no double bonds

saturated fatty acids –> atherosclerosis

Question 6

unsaturated

Answer 6

1 or more double bonds
polyunsaturated = more than 1
double bonds usually in cis configuration

Question 7

trans fat

Answer 7

double bond in trans configuration

not natural, result of chemical treatment

Question 8

polar heads have …

Answer 8

ionized carboxyl group

Question 9

omega #ing

Answer 9

start at methyl end, count towards double bond

Question 10

delta #ing

Answer 10

start at carboxyl end, count towards double bond

common in biochem

Question 11

essential fatty acids

Answer 11

can’t make, need in diet
delta >9
ex: linoleic and linolenic

Question 12

fat structure

Answer 12

glycerol with 3 fatty acids

Question 13

glycerophospholipid structure

Answer 13

glycerol with 2 fatty acids, a phosphate group

Question 14

2 main categories of molecules in membranes

Answer 14

glycerophospholipids/ phosphoglycerides

sphingolipids

Question 15

phosphatidate/ phosphatidic acid

Answer 15

simplest glycerophospholipid

branch point for synthesis of glycerophospholipids and fats

Question 16

attach new things to phosphate on phosphatidic acid –>

Answer 16

new glycerophospholipids

general name: phosphatidyl -X

Question 17

most sphingolipids don’t have

Answer 17

phosphate

Question 18

fatty acid attached to amine –>

Answer 18

sphingolipid

looks like sphingosine because has amine

Question 19

sphingolipids have 2 __

Answer 19

fatty acids

important b.c. structural restriction for what can fit in bilayer

Question 20

sphingolipids found more often in…

Answer 20

nerve and brain tissue

ex: sphingomyelin

Question 21

attachment of sugars to sphingolipids

Answer 21

single sugar –> cerebroside

complex sugars –> ganglioside

Question 22

steroids

Answer 22

lipids derived from cholesterol

not derived from fatty acids

Question 23

cholesterol

Answer 23

important for membrane stability

prominent in brain membranes (14% of dry weight of brain)

Question 24

microbes that live in hydrothermal vents have..

Answer 24

different lipid in membranes: ether lipids (instead of ester bonds)

Question 25

fatty acids in water –>

Answer 25

micelle: tails point into circle, heads point out
ex: soap, central nonpolar sticks to grease

Question 26

liposome

Answer 26

artificial lipid bilayer (used in labs)
donut shaped, water in middle, looks like cell
mix glverophospholipids and sphingolipids in water –> spontaneously form structure

Question 27

liposomes useful for

Answer 27

to fuse with cell and deliver certain substances into cell, when not easily transported across membrane

Question 28

4 types of membrane proteins

Answer 28

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

Question 29

bacteriorhodopsin

Answer 29

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

Question 30

membrane spanning proteins have __

Answer 30

non polar membrane crossing regions
polar short sections
(can use computer to predict aa sequence and if it’s a membrane protein)

Question 31

prostaglandins

Answer 31

arise from arachadonic acid by prostaglandin synthase (COX enzyme, peripheral protein)
associated with pain, inflammation and uterine contraction

Question 32

prostaglandin synthesis inhibited by

Answer 32

NSAIDs (inhibit cox enzymes)

Question 33

Asprin and stomach problems

Answer 33

some prostaglandins necessary for synthesis of intestinal tissue (COX 1), NSAIDs can cause stomach issues

Question 34

tried to inhibit just cox 2 in joints…

Answer 34

ex: vioxx, Celebrex

recall for side effect of damaging heart tissue

Question 35

___ retain fluidity at lower temps

Answer 35

shorter, more unsaturated fatty acids

ex: fish membranes - unsaturated and polyunsaturated

Question 36

___ not as fluid

Answer 36

longer, saturated fatty acids

Question 37

fluid mosaic model

Answer 37

things moving in membrane very fast

use laser to bleach cell in specific place, watch how long it takes to for color to disappear

Question 38

lateral diffusion

Answer 38

rapid

Question 39

transverse diffusion

Answer 39

flip-flop
very slow
flipase catalyzes (fact that we have flipases = arrangement is important)

Question 40

Tm

Answer 40

midpoint of conversion between solid and fluid state
* a temperature
(midpoint of steep part of curve between flat states)

Question 41

cholesterol and Tm

Answer 41

cholesterol does not change Tm

widens the range of the transition temps between solid and fluid

Question 42

Sodium Potassium ATPase

Answer 42

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

Question 43

Na/K ATPase is ___ transport mechanism…

Answer 43

electrogenic transport mechanism

Question 44

bacterial membranes

Answer 44

have layers and covalent bonds

different aa’s in D configuration (cant be attacked by proteases)

Question 45

receptor mediated endocytosis

Answer 45

ex: cholesterol enters via LDLs that attach to receptors on cell’s surface
entire LDL with cholesterol taken into cell