Membrane Structure and Function

Question 1

Contents of the phospholipid bilayer

Answer 1

Hydrophilic head, hydrophobic tails, hydrophobic tails, hydrophilic head

Question 2

Fluid mosaic model

Answer 2

the membrane is a mosaic of proteins molecules bobbing an a fluid bilayer of phospholipids

Question 3

Unsaturated hydrocarbon tails

Answer 3

tails that are kinked and prevent packing, enhancing membrane fluidity

Question 4

Viscous hydrocarbon tails

Answer 4

unsaturated tiles pack together, increasing membrane viscosity

Question 5

Integral proteins

Answer 5

penetrate the hydrophobic interior of the lipid bilayer

Question 6

Peripheral proteins

Answer 6

appendages loosely bound to the surface of the membrane

Question 7

Functions of membrane proteins

Answer 7

transport, enzyme activity, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and the ECM

Question 8

Permeability of the lipid bilayer

Answer 8

nonpolar molecules can cross easily as they are hydrophobic

Question 9

Transport proteins

Answer 9

Channel proteins that certain molecules or ions can use its hydrophilic tunnel to pass through the membrane

Question 10

Carrier proteins

Answer 10

proteins that hold and change shape that shuttles things across the membrane

Question 11

Diffusion

Answer 11

the spontaneous movement of particles of any substance so that they spread out into available space until dynamic equilibrium is reached

Question 12

Concentration gradient

Answer 12

the region along which the density increases or decreases; potential energy and drives diffusion

Question 13

Passive transport

Answer 13

transportation of substances that does not require the cell to expend energy

Question 14

Osmosis

Answer 14

the passive transport of water; diffusion of water across a selectively permeable membrane

Question 15

Facilitated Diffusion

Answer 15

passive transport aided by proteins

Question 16

Ion channels

Answer 16

channels in the membrane that transport ions

Question 17

Gated channels

Answer 17

channels in the membrane that open in response to a stimulus

Question 18

Active transport

Answer 18

use of energy to transfer solutes against their gradients

Question 19

Membrane potential

Answer 19

the voltage across a membrane that acts as an energy source like a battery and affects that traffic of all charged substances across the membrane ;

Question 20

electrochemical gradient

Answer 20

two forces that drive diffusion of ions across the membrane is the ion concentration gradient (chemical force) and membrane potential on ions movement (electrical force)

Question 21

electrogenic pump

Answer 21

transport protein that generates voltage across membranep

Question 22

proton pump

Answer 22

transport protein that actively transports protons across membrane out of the cell

Question 23

Cotransport

Answer 23

active transport driven by a concentration gradient

Question 24

Exocytosis

Answer 24

the cell secretes molecules by the fusion of vesicles with the plasma membrane

Question 25

endocytosis

Answer 25

the cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane

Question 26

Ligans

Answer 26

any molecule that binds specifically to a receptor site on another molecule

Question 27

Phagocytosis

Answer 27

a cell engulfs a particle by extending pseudopodia around it and packing within a membranous sac (food vacuole) that will be digested after the food vacuole fuses with a lysosome

Question 28

Pinocytosis

Answer 28

the cell "gulps" ECF into tiny vesicles by infoldings of the plasma membrane