Chapter 11- Membrane Structure

Question 1

cell membranes consist of a _____ double layer, or a ____ of lipid molecules

Answer 1

continuous, bilayer

Question 2

the ____ ____ provides the basic structure and barrier function of all cell membranes

Answer 2

lipid bilayer

Question 3

Membrane lipid molecules are ___, meaning they have both hydrophobic and hydrophilic regions

Answer 3

amphipathic

Question 4

three major classes of membrane lipid molecules

Answer 4

phospholipids, sterols, glycolipids

Question 5

the lipid bilayer is ____, and individual lipid molecules are able to ___ within their own monolayer

Answer 5

fluid, diffuse

Question 6

cells that live at different temperatures maintain their membrane fluidity by modifying their ___ ____ of their membranes

Answer 6

lipid composition

Question 7

Membrane proteins are responsible for most functions of membranes including, ___ of small, ___-___ molecules across the lipid bilayer

Answer 7

transport, water-soluble

Question 8

______ proteins extend across the lipid bilayer usually as one or more alpha helices, but sometimes as a ___ sheet rolled into the form of a barrel

Answer 8

Transmembrane, beta

Question 9

Other membrane proteins do not extend across the lipid bilayer but are ___ to ___ or ___ side of the membrane

Answer 9

attached, one, another

Question 10

most cell membranes are supported by an attached ____ of ____

Answer 10

framework, proteins

Question 11

many of the proteins and some of the lipids exposed on the surface of the cell have attached ___ __

Answer 11

suagr chains

Question 12

the ____ ____ helps protect and lubricate the cell surface, while also being recognized in cell to cell recongition

Answer 12

carbohydrate layer

Question 13

specialized layer of cytoplasm on the inner face of the plasma membrane. In animal cells, it is rich in actin filaments that govern cell shape and drive cell movement

Answer 13

cell cortex

Question 14

this short rigid lipid molecule, found in large amounts in the membrane, makes the lipid bilayer less flexible

Answer 14

cholesterol

Question 15

soapy substance used to solubilize membrane proteins

Answer 15

detergent

Question 16

protective layer of carbohydrates on the outside surface of the plasma membrane formed by sugar residues of membrane glycoproteins, proteoglycans, and glycolipids

Answer 16

glycocalyx

Question 17

functionally and specialized region in the membrane of a cell or organelle; typically characterized by the presence of specific proteins

Answer 17

membrane domain

Question 18

organic molecule that contains a full complement of hydrogen, aka no double bonds

Answer 18

saturated

Question 19

organic molecule that contains one or more double bonds or triple bonds between its carbon molecules…. creates a kink

Answer 19

unsaturated

Question 20

structure of cell membranes is determined by the way the membrane lipids behave in an ____ environment

Answer 20

aqueous

Question 21

the molecules of a bilayer are able to ____ ____ to eliminate a free edge if a tear is made

Answer 21

spontaneously rearrange

Question 22

the ___ and more ___ the packing of phospholipid tails, the more viscous and less fluid the bilayer will be

Answer 22

closely, regular

Question 23

the two major properties of hydrocarbon tails that affect how tightly they pack in the bilayer are ___ & ____

Answer 23

length, number of double bonds they contain

Question 24

lipid bilayers that contain a larger proportion of unsaturated hydrocarbon tails are more ___ than those with lower proportions

Answer 24

fluid

Question 25

new phospholipids can be synthesized by ___ bound to the cytosolic surface of the ___

Answer 25

enzymes, ER

Question 26

proteins constitute around ___% of the mass of most plasma membranes

Answer 26

50

Question 27

proteins directly attached to lipid bilayer that can be removed only by disrupting the bilayer with detergents are known as

Answer 27

integral membrane proteins

Question 28

these proteins can be released from the membrane by more gentle extraction procedures that interfere with protein-protein interactions but leave lipid bilayer intact

Answer 28

peripheral membrane proteins

Question 29

in many transmembrane proteins the polypeptide chain crosses the membrane only ___

Answer 29

once

Question 30

____ proteins allow the passage of small nutrients, metabolites, and inorganic ions across their outer membrane, and also prevent unwanted larger molecules from crossing

Answer 30

porins

Question 31

proteins in the plasma membrane that have oligosaccharides linked to them are called

Answer 31

glycoproteins

Question 32

membrane proteins that contain one or more long polysaccharide chain

Answer 32

proteoglycans