Topic 3

Question 1

Phospholipids are amphipathic moleciules

Answer 1

containing hydrophopic and hydrophilic regions

Question 2

Fluid mosaic model

Answer 2

a membrane is a fluid structure with a “mosaic” of proteins embedded in it

Question 3

Larry Fry and Michael Edidin

Answer 3

differentially labelled membrane proteins of mouse and human cells

Question 4

Membrane fluidity

Answer 4

affects the permeability of the membrane and the function of its proteins

Question 5

Affect the fluidity of a membrane

Answer 5

Temperature
Fatty acid tails (longer=more viscous
shorter=fluid

Question 6

Sterols Regulate Membrane Fluidity

Answer 6

Animal cells insert cholesterol into bilayer Prevent freezing by stopping phospholipids from packing to tightly
Prevent melting by restraining phospholipid movent

Question 7

peripheral proteins

Answer 7

bound to the surface of the membrane

Question 8

integral proteins

Answer 8

penetrate the hydrophopic core and are embedded in membrane

Question 9

Transmembrane proteins

Answer 9

Integral proteins that span membrane

Question 10

Six major functions of membrane proteins

Answer 10

1) transport
2) enzymes
3) signalling
4) cell - cell recognition
5) intercellular joining
6) anchoring

Question 11

Two types of transport

Answer 11

Passive: based entirely on diffusion (moves down/with a concentration gradient
Active: Requires energy (Moves up/against a concentration gradient

Question 12

Tonicity

Answer 12

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

Question 13

isotonic solution

Answer 13

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

Question 14

hypertonic solution

Answer 14

solute concentration is greater than inside the cell; cell loses water

Question 15

hypotonic solution

Answer 15

solute concentration is greater than inside the cell; cell gain water

Question 16

carrier proteins

Answer 16

undergo subtle change in shape (conformation) that translocate the solute binding site across the membrane

Question 17

Aquaporins

Answer 17

allow water to move across the membrane at rates that can sustain life

Question 18

faciltated difussion

Answer 18

the solute moves down its concentration gradient and transport requires no energy

Question 19

active transport

Answer 19

moves substances against their concentration gradients

Question 20

The sodium-Potassium

Answer 20

a specific case of active transport

Question 21

Membrane potential

Answer 21

the voltage difference across a membrane

Question 22

Cotransport

Answer 22

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

Question 23

Large molecules, such as polysaccharides and proteins, cross membrane via…

Answer 23

vesicles (Bulk transport)

Question 24

Exocytosis

Answer 24

transport vesicles migrate to the membrane, fuse with it, and release their contents to the outside of

Question 25

Endocytosis

Answer 25

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