Exam 3: Ch 10 Biomembrane Structure

Question 1

membrane transport proteins

Answer 1

enable ions, sugars, aa and vitamins to cross the semi permeable phospholipid bilayer

Question 2

receptors

Answer 2

proteins in the cell membrane that allow the cell to recognize chemical signals to adjust metabolism or gene expression

Question 3

cytoskeleton

Answer 3

a network of protein filaments in the cytosol

provide mechanical support for shape and cell movement

Question 4

fluid mosaic model

Answer 4

individual lipids can move horizontally in the membrane and spin in place (but not flip orientation)

membrane fluidity

noncovalent van der waals interactions

Question 5

most common phospholipid in membranes

Answer 5

phosphoglycerides

Question 6

amphipathic membrane structure

Answer 6

fatty acid hydrophobic hydrocarbon tails

polar hydrophilic heads

Question 7

3 types of membrane lipid

Answer 7

phospholipids

sphingolipids

sterols

Question 8

amphipathic things spontaneously form…

Answer 8

micelles

liposomes

membrane bilayers

Question 9

artificial membranes lack _____

Answer 9

proteins

Question 10

lipid raft

Answer 10

less fluid patches of membrane

more cholesterol (stability)

contain plasma membrane proteins involved in transmitting extracellular signals to the inside

Question 11

sphingolipids have different head groups than phospholipids

Answer 11

phosphotidylinositol

signaling molecule

DIAG - diacyl glycerol triphosphate

Question 12

why dont cells fall apart if the membrane is so fluid?

Answer 12

cell walls (plants/bacteria)

ECM

cholesterol

Question 13

type of structure formed by pure phospholipids depends on…

Answer 13

length of tails

degree of saturation

temperature

Question 14

leaflet

Answer 14

half of the phospholipid bilayer

Question 15

phosphatidylcholine

Answer 15

type of phosphoglyceride

most abundant phospholipid in membrane

choline polar head group (OH + phosphate)

Question 16

phospholipases

Answer 16

enzymes that celave ester bonds

produce lysophospholipids (only 1 acyl tail) that are signaling molecules

recognized by receptors and affect physical properties of the memb.

Question 17

plasmalogens

Answer 17

ether linkage - greater chemical stability

human brain and heart

Question 18

structure of sterols

Answer 18

4 rings

cholesterol has an OH on one ring

Question 19

effect of sterols on membranes

Answer 19

structural support

prevent extremely tight packing to allow more fluidity

Question 20

fluorescence recovery after photobleaching (FRAP)

Answer 20

phospholipids with a fluorescent substituent are used to monitor lipid movement

shows lateral movement of proteins and lipids

Question 21

do sphingomyelins form more gel-like and thicker bilayers than phosphoglycerides?

Answer 21

yes

Question 22

bilayers made of cylindrical lipids (long tails and large head groups) are ____, while bilayers made from cone lipids (small head groups) are ______

Answer 22

flat, curved

Question 23

flippase

Answer 23

ATP powered transport proteins

flip exoplasmic lipids (phospholipids) from cytosolic leaflet to exoplasmic leaflet where they function

ex. phosphatidylserine flipped to exoplasmic side where it activates enzymes involved in blood clotting

Question 24

lipid droplet

Answer 24

vesicles made of triglycerides and cholesterol esters that originate from the ER and serve as lipid storage

Question 25

extracellular domain functions

Answer 25

bind extracellular molecules like signaling proteins, ions, and small metabolites

Question 26

intramembrane domain functions

Answer 26

form channels/pores

organize membrane proteins into larger assemblies

Question 27

intramembrane domain functions

Answer 27

anchoring cytoskeletal proteins to the membrane to trigger intracellular signaling pathways

organizing membrane proteins into larger assemblies

Question 28

integral membrane proteins (transmembrane)

Answer 28

span the bilayers and have 3 domains (cytosolic, exoplasmic, transmembrane)

can be attached to ECM

transmembrane domain made of alpha helices and beta sheets

Question 29

lipid-anchored membrane proteins

Answer 29

bound covalently to 1+ lipid molecules

hydrophobic domain embedded in one leaflet and serves as the anchor

Question 30

peripheral membrane proteins

Answer 30

bound to the memb. indirectly by interactions w/ integral or lipid-anchored memb. proteins or directly by interactions w/ head groups

can be attached to ECM too

Question 31

single-pass transmembrane protein

Answer 31

has only 1 membrane spanning alpha helix

ex. Glycophorin A

Question 32

multipass transmembrane protein

Answer 32

an important group has 7 membrane spanning alpha helices

ex. G protein-coupled cell-surface receptors (bacteriorhodopsin)

Question 33

aquaporin

Answer 33

highly conserved proteins that transport water, glycerol, and other hydrophilic molecules

multipass (6 alpha helices) tetramers of 4 identical subunits

ex. glycerol channel Glpf

Question 34

aquaporin 0

Answer 34

most abundant protein in the plasma membrane of fiber cells in the lens of the eye

annular phospholipids - form a tight ring

Question 35

multiple beta strands in _____ form membrane spanning barrels

Answer 35

porins

hydrophilic interior and hydrophobic exterior

Question 36

2 examples of lipid-anchored membrane proteins

Answer 36

Ras (GTPase superfamily)

Rab (GTPase superfamily)

Question 37

orientation of transmembrane glycoproteins/glycolipids

Answer 37

carbohydrate chains in exoplasmic domain

makes them available to interact with ECM, lectins, growth factors, and Ab

Question 38

proteins can be removed from membranes by ______ or high-____ solutions

Answer 38

detergents, high-salt solutions

Question 39

detergent

Answer 39

amphipathic molecules that disrupt membranes by intercalating into them

ex. bile salts, SDS

Question 40

critical micelle concentration (CMC)

Answer 40

concentration of detergent at which micelles form