Lecture 8 Membranes

Question 1

amphipathic molecules

Answer 1

containing hydrophobic and hydrophillic regions

Question 2

fluid mosaic model

Answer 2

membrane is a fluid structure with a “mosaic” of various proteins embedded (“bobbing”) in it

Question 3

membrane

Answer 3

collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer

Question 4

peripheral proteins

Answer 4

bound to the surface of the membrane

Question 5

integral proteins

Answer 5

penetrate the hydrophobic core

Question 6

transmembrane

Answer 6

integral proteins that span the membrane

Question 7

transport proteins

Answer 7

allow the passage of a specific hydrophilic substance across the membrane

Question 8

channel proteins

Answer 8

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

Question 9

aquaporins

Answer 9

channel protein that facilitates the passage of water

Question 10

carrier proteins

Answer 10

bind to molecules and undergo a subtle change of shape to translocate the solute-binding site across the membrane

Question 11

passive transport

Answer 11

diffusion of a substance across a membrane with no energy investment

Question 12

diffusion

Answer 12

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

Question 13

concentration gradient

Answer 13

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

Question 14

osmosis

Answer 14

the diffusion of water across a selectively permeable membrane

Question 15

tonicity

Answer 15

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

Question 16

isotonic

Answer 16

solute concentration is same of that inside the cell; no net water movement across the plasma membrane

Question 17

hypertonic

Answer 17

solute concentration is greater than that inside the cell, cell loses water.

Question 18

hypotonic

Answer 18

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

Question 19

facilitated diffusion

Answer 19

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

Question 20

channel proteins

Answer 20

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

Question 21

ion channels

Answer 21

channel protein that open or lose in response to a stimulus (gated channels)

Question 22

active transport

Answer 22

moves substances against their concentration gradients

Question 23

electrogenic pump

Answer 23

transport protein that generates voltage across a membrane, helps store energy which can be used for cellular work

Question 24

proton pump

Answer 24

transports H+ inside / outside the cell

Question 25

membrane potential

Answer 25

voltage difference across a membrane

Question 26

electrochemical gradient

Answer 26

drive the diffusion of ions across a membrane

Question 27

chemical force

Answer 27

ion’s concentration gradient

Question 28

electrical potential

Answer 28

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

Question 29

cotransport

Answer 29

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