Membrane Proteins

Question 1

diffusion

Answer 1

spontaneous movement of a substance from 1 region to another, often w/ net movement from high conc. to low conc.

Question 2

facilitated diffusion

Answer 2

passive transport of a substance across a membrane w/ assistance of transmembrane carrier proteins or channel proteins

Question 3

carrier protein

Answer 3

specialized membrane proteins that change shape during the transport process

Question 4

channel protein

Answer 4

enable ions or polar molecules to move across lipid bilayers efficiently in response to existing gradient

Question 5

active transport

Answer 5

movement of ions/molecules across membrane against an electrochemical gradient

• requires energy & assistance of transport protein
• must counteract entropy ↓

Question 6

protein models

Answer 6

(1) fluid mosaic model

(2) sandwich model

Question 7

freeze-fracture electron microscopy

Answer 7

innovative technique for visualizing surface of plasma membranes

Question 8

peripheral membrane protein

Answer 8

protein that binds to membrane w/out passing through & a protein does not span entire lipid bilayer & associates w/ only one side of bilayer

• some only found in interior cell
• others only found on exterior cell
• often attached to transmembrane proteins
• come off easily

Question 9

integral membrane protein

Answer 9

protein that spans membrane & has segments facing both interior & exterior surfaces

• hydrophobic embedded part
• some transmembrane parts

aka. transmembrane protein

Question 10

detergent

Answer 10

small amphipathic molecule used to solubilize hydrophobic molecules in aq. solution

Question 11

electrochemical gradient

Answer 11

combo of ion’s [] gradient & electrical (charge) gradient across a membrane that affects ion diffusion across membrane

electrical + chemical -> diffusion

Question 12

channel proteins

Answer 12

types of pores in cell membrane

• enable ions / polar molecules to move across lipid bilayer in response to existing gradient
• selective: permits particular types of ions or small molecules to pass through only

Question 13

gated channel

Answer 13

channel protein that opens/closes in response to specific stimulus

(ie) aquaporin & ion channel
(ie) voltage & ligand gated

Question 14

aquaporin

Answer 14

type of channel protein in which water moves cross plasma membrane over 10x faster than w/out aquaporin

“water-pores”

Question 15

ion channel

Answer 15

specialized protein channel that allows certain ions to diffuse across plasma membrane down an electrochemical gradient
- form pores in membrane, which is where ions move through

Question 16

passive transport

Answer 16

powered by diffusion along electrochemical gradient

• no need energy
• use gradients as force

(ie) facilitated diffusion

Question 17

secondary active transport

Answer 17

gradient set up by pump provides energy required to pwr movement of diff. molecule against its particular gradient

• link passive to active
• glucose movement in small intestine against [] gradient
• Na+ down gradient, glucose against gradient
• no ATP

aka. cotransport

Question 18

pump

Answer 18

protein membrane that can:

(1) hydrolyze ATP
(2) change shape
(3) pwr active transport of specific ion/small molecule across plasma membrane against electrochemical gradient
- independent of gradients

Question 19

primary active transport

Answer 19

critical for membrane potential

Question 20

channel fcn

Answer 20

(1) passive transport
(2) facilitated diffusion
(3) electrochemical gradient

Question 21

carrier protein fcn

Answer 21

(1) passive transport
(2) facilitated diffusion
(3) electrochemical gradient

Question 22

voltage gated

Answer 22

charge (+/-) depends on open/close

Question 23

ligand gated

Answer 23

depends on if ligand (binds to receptor) is on channel or not

Question 24

membrane-associated proteins

Answer 24

(1) peripheral membrane protein
(2) integral membrane protein
(3) glycoprotein

Question 25

glycoprotein

Answer 25

only present on exterior of cell or inside of golgi

• creates diff. blood types
• cell receptors