Chapter 11

Question 1

Functions of the cell membrane

Answer 1

receiving information, import/export of small molecules, capacity for movement and expansion

Question 2

Basic structure of the membrane and function

Answer 2

Lipid bilayer; serves as a permeability barrier to most water soluble molecules

Question 3

which formation of phospholipids is energetically favorable

Answer 3

sealed compartments of bilayer membrane

Question 4

fatty acid structure

Answer 4

carboxyl group attached to hydrocarbon tail

Question 5

phospholipid structure

Answer 5

two fatty acid tails attached to a glycerol, which is attached to a phosphate group and a hydrophilic group

Question 6

which functional group does a hydrocarbon chain need to have to be a fatty acid

Answer 6

carboxyl group (fatty acids are carboxylic acids)

Question 7

triglyceride polarity

Answer 7

completely nonpolar; hydrophobic; only found in lipid droplets

Question 8

lipase function

Answer 8

breaks TG into glycerol and fatty acids

Question 9

saturated fatty acids

Answer 9

no double bonds between C atoms, straight line

Question 10

monounsaturated fatty acids

Answer 10

1 double bonds between C atoms; causes kink

Question 11

polyunsaturated fatty acids

Answer 11

2 or more double bonds between C atoms

Question 12

fatty acid categorization (X:X)

Answer 12

(Carbons: Double Bonds)

Question 13

what type of hydrocarbon chains are more rigid

Answer 13

saturated (pack tightly) and longer

Question 14

what type of hydrocarbon chain is more fluid

Answer 14

unsaturated (less packed) and shorter

Question 15

at a higher temp, mb fluidity is high– to reduce membrane fluidity . . .

Answer 15

longer and more saturated hydrocarbon chains

Question 16

cholesterol impact on mb fluidity

Answer 16

acts as a buffer; increases fluidity in cold temps, decreases fluidity in warm temps

Question 17

functions of membrane proteins

Answer 17

transporters and channels, anchors, receptors, and enzymes

Question 18

integral membrane proteins

Answer 18

directly attached to lipid bilayer, only removable by disrupting membrane (transmembrane, monolayer associated, lipid-linked)

Question 19

peripheral membrane proteins

Answer 19

attached to integral membrane proteins, can be removed without disrupting membrane bilayer

Question 20

transmembrane protein

Answer 20

amphipathic; extend through bilayer; single pass or multi-pass; alpha helices or beta barrel

Question 21

amphipathic helix in a multi-pass membrane protein/monolayer associated protein

Answer 21

hydrophilic side chains on one side of helix, hydrophobic on opposite side

Question 22

multipass membrane channel structure

Answer 22

alpha helices in rings with hydrophilic side chains pointing in and hydrophobic side chains facing membrane. (act as channels for small hydrophilic molecules)

Question 23

are alpha helices and beta sheets motifs or domains

Answer 23

motifs

Question 24

alpha helices form hydrogen bonds within one peptide backbone with amino acids that are ____ amino acids away

Answer 24

4

Question 25

beta sheets form hydrogen bonds between amino aicds _______

Answer 25

of adjacent peptide backbones

Question 26

beta barrels are found in what type of protein

Answer 26

porin proteins (water filled pores in mitochondrial and bacterial outer membranes)

Question 27

beta barrel structure and function

Answer 27

16-stranded beta-sheet in its tertiary structure; hydrophobic side chains on the outside, hydrophilic on the inside allow small nutrients and inorganic ions across membranes

Question 28

cell cortex structure

Answer 28

meshwork of fibrous proteins that is attached to cytosolic surface of membrane via anchor proteins

Question 29

cell cortex function

Answer 29

determines shape and mechanical properties of the cell/PM

Question 30

cortex is made largely of what protein

Answer 30

spectrin; consists of actin filaments as well; connected to PM by spectrin/transmembrane protein interaction

Question 31

which part of the bilayer are glycolipids mainly found

Answer 31

non-cytosolic

Question 32

where do glycolipids acquire their sugar groups

Answer 32

golgi

Question 33

what is the glycocalyx composed of

Answer 33

sugars attached to both lipids and proteins in the extracellular surface of the PM

Question 34

glycocalyx function

Answer 34

absorbs water, slimy surface, prevents blood cells sticking to one another/blood vessel walls, cell-cel recognition, motility

Question 35

oligosaccharides on glycolipids and glycoproteins of neutrophils function

Answer 35

"ID tags" recognized by lectins of endothelial cells lining the blood vessels at infection site, allowing neutrophils through the tissue into infection site

Question 36

new phospholipids are produced by what

Answer 36

enzymes bound to the cytosolic half of the ER membrane; causing curvature by addition of phospholipids only to cytosolic half

Question 37

scramblase function

Answer 37

proteins that randomly transfer phospholipids from one monolayer to another, allow symmetric membrane growth NONSPECIFIC, BIDIRECTIONAL, NO ENERGY required

Question 38

flippases

Answer 38

enzymes in golgi membrane that remove specific phospholipids from the non-cytosolic side and flip to cytosolic side, making membrane asymmetrical ENERGY REQUIRED

Question 39

when vesicles form from an organelle and merge with the PM, how does the orientation of the bilayers change?

Answer 39

It doesn't, cytosolic side remains cytosolic

Question 40

how do cells contain proteins in specialized membrane domains on the surface of cells/organelles

Answer 40

anchor to cell cortex anchor to ECM surface proteins of 2 cells anchor each other diffusion barrier restricts diffusion of proteins to certain side of cell

Question 41

example of a lateral diffusion barrier

Answer 41

cells in the intestine have a side that uptake nutrients, and a side that exports solutes into the bloodstream apical membrane proteins (uptake) are prevented from crossing to basal domain and vice versa by a tight junction

Question 42

FRAP

Answer 42

used to measure the rate of lateral diffusion of membrane proteins

Question 43

FRAP steps

Answer 43

fluorescently labeled (GFP) membrane proteins bleached in small area fluorescent intensity recovers as unbleached proteins diffuse into area rate of "fluorescent recovery" is direct measure of rate of lateral diffusion in the membrane

Question 44

detergents

Answer 44

small amphipathic lipid-like molecules that from phospholipids by only have one tail

Question 45

how do detergents work

Answer 45

single tail allows them to squeeze into membranes and aggregate into micelles trapping and separating lipids

Question 46

how are detergents used to solubilize and reconstitute membrane proteins

Answer 46

detergent added to membrane solution, which solubilizes proteins and creates lipid-detergent micelles protein of interest separated from solution addition of pure phospholipids/detergent micelles creates protein/artificial bilayer complex