Chapter 7: Membrane Structure and Function

Question 1

allowing some substances to cross it more easily than others

Answer 1

selective permeability

Question 2

molecules containing hydrophobic and hydrophilic regions

Answer 2

amphipathic molecules

Question 3

the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids is called what

Answer 3

fluid mosaic modle

Question 4

the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids what

Answer 4

weak hydrophobic interactions

Question 5

form the main fabric of the membrane

Answer 5

phospholipids

Question 6

determine most of the membrane’s functions

Answer 6

proteins

Question 7

are bound to the surface of the membrane

Answer 7

peripheral proteins

Question 8

penetrate the hydrophobic core

Answer 8

integral proteins

Question 9

integral proteins that span the membrane

Answer 9

transmembrane proteins

Question 10

cell-surface membrane functions

Answer 10

• Transport
• Enzymatic activity
• Signal transduction
• Cell-cell recognition
• Intercellular joining
• Attachment to the
  cytoskeleton and
  extracellular matrix
  (ECM)

Question 11

membrane carbohydrates covalently bonded to lipids

Answer 11

glycolipids or glycoproteins

Question 12

are selectively permeable,
regulating the cell’s molecular traffic

Answer 12

Plasma membranes

Question 13

can dissolve in the lipid bilayer and
pass through the membrane rapidly

Answer 13

Hydrophobic (nonpolar) molecules

Question 14

molecules including ions and polar
molecules do not cross the membrane easily

Answer 14

Hydrophilic molecules

Question 15

allow passage of hydrophilic
substances across the membrane

Answer 15

transport proteins

Question 16

have a hydrophilic channel that certain molecules or
ions can use as a tunnel

Answer 16

channel proteins

Question 17

greatly facilitate
the passage of water molecules

Answer 17

aquaporins

Question 18

bind
to molecules and change shape to shuttle them
across the membrane

Answer 18

carrier proteins

Question 19

is the tendency for molecules to spread
out evenly into the available space

Answer 19

diffusion

Question 20

the region along which the density of a
chemical substance increases or decreases

Answer 20

concentration
gradient

Question 21

The diffusion of a substance across a biological
membrane is what

Answer 21

passive transport

Question 22

is the diffusion of water across a
selectively permeable membrane

Answer 22

osmosis

Question 23

is the ability of a surrounding solution to
cause a cell to gain or lose water

Answer 23

tonicity

Question 24

Solute concentration is the same
as that inside the cell; no net water movement
across the plasma membrane

Answer 24

isotonic

Question 25

Solute concentration is greater than that inside the cell; cell loses water

Answer 25

Hypertonic solution

Question 26

Solute concentration is less than that inside the cell; cell gains water

Answer 26

Hypotonic solution

Question 27

help maintain water balance

Answer 27

cell walls

Question 28

a firm cell

Answer 28

turgid

Question 29

a limp cell

Answer 29

flaccid

Question 30

plant cells lose water in this environment

Answer 30

hypertonic environment

Question 31

what effects happens when the membrane pulls away from the cell wall, causing the plant to wilt

Answer 31

plasmolysis

Question 32

create osmotic problems for organisms that have cells without rigid walls

Answer 32

Hypertonic or hypotonic environments

Question 33

the control of solute concentrations and water balance, is a necessary adaptation for life in such environments

Answer 33

osmoregulation

Question 34

transport proteins speed the passive movement of molecules across the plasma membrane

Answer 34

facilitated diffusion

Question 35

provide corridors that allow a specific molecule or ion to cross the membrane

Answer 35

channel proteins

Question 36

facilitate the diffusion of water

Answer 36

aquaporins

Question 37

facilitate the transport of ions

Answer 37

ion channels

Question 38

open or close in response to a stimulus

Answer 38

gated channels

Question 39

undergo a subtle change in shape that translocates the solute-binding site across the membrane

Answer 39

carrier proteins

Question 40

requires energy, usually in the form of ATP hydrolysis, to move substances against their concentration gradients

Answer 40

Active transport

Question 41

determine most of the membrane’s functions

Answer 41

proteins

Question 42

form the main fabric of the membrane

Answer 42

phospholipid

Question 43

allows cells to maintain concentration gradients that differ from their surroundings

Answer 43

active transport

Question 44

A pump where a transport protein is energized by transfer of a phosphate group from the hydrolysis of ATP

Answer 44

sodium-potassium pump

Question 45

is the voltage across a membrane

Answer 45

membrane potential

Question 46

is created by differences in the distribution of positive and negative ions across a membrane

Answer 46

voltage

Question 47

drive the diffusion of ions across a membrane

Answer 47

electrochemical gradient

Question 48

the ion’s concentration gradient

Answer 48

chemical force

Question 49

the effect of the membrane potential on the ion’s movement

Answer 49

electrical force

Question 50

a pump where there is a transport protein that generates voltage across a membrane

Answer 50

electrogenic pump

Question 51

is the major electrogenic pump of animal cells

Answer 51

sodium-potassium pump

Question 52

The main electrogenic pump of plants, fungi, and bacteria is what

Answer 52

proton pump

Question 53

actively transports hydrogen ions (H+) out of the cell

Answer 53

proton pump

Question 54

help store energy that can be used for cellular work

Answer 54

Electrogenic pumps

Question 55

occurs when active transport of a solute indirectly drives transport of other substances

Answer 55

Cotransport

Question 56

in what process does the transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell

Answer 56

exocytosis

Question 57

the cell takes in macromolecules by forming vesicles from the plasma membrane

Answer 57

endocytosis

Question 58

a reversal of exocytosis

Answer 58

endocytosis

Question 59

three types of endocytosis

Answer 59

* Phagocytosis * Pinocytosis * Receptor-mediated endocytosis

Question 60

“cellular eating”

Answer 60

Phagocytosis

Question 61

“cellular drinking”

Answer 61

Pinocytosis

Question 62

a cell engulfs a particle in a vacuole

Answer 62

Phagocytosis

Question 63

molecules dissolved in droplets are taken up when extracellular fluid is “gulped” into tiny vesicles

Answer 63

pinocytosis

Question 64

binding of specific solutes to receptors triggers vesicle formation

Answer 64

receptor-mediated endocytosis

Question 65

Receptor proteins, receptors, and other molecules from the extracellular fluid are transported in the what

Answer 65

vesicles

Question 66

use receptor-mediated endocytosis to take in cholesterol

Answer 66

human cells

Question 67

Individuals with the disease familial hypercholesterolemia have missing or defective what

Answer 67

LDL receptor proteins