Biological Membranes

Question 1

What type of compounds are allowed to easily pass through the cell membrane ?

Answer 1

Fat soluble compounds

*Larger H20 soluble compounds require carrier to pass

Question 2

What theory underlies the structure & function of the cell membrane ?

Answer 2

Fluid mosaic model

Question 3

How do triacylglycerols & glycerophospholipid (aka phospholipids) differ ?

Answer 3

Phospholipids have a phosphate group, triacylglycerols don’t

Question 4

What are the main functions of cholesterol ?

Answer 4

Maintain membrane fluidity & synthesize steroids

Question 5

Which class of lipids are extremely hydrophobic & mainly constitutes plant cell membranes ?

Answer 5

Waxes

*Composed of long-chain fatty acids & long-chain alcohol

Question 6

What are the 3 membrane proteins as accounted for by the fluid mosaic model ?

Answer 6

Transmembrane: pass completely through lipid bilayer
Embedded: either exterior or interior
Membrane-associated (peripheral): bound through electrostatic interactions w/ lipid bilayer
*Transmembrane + embedded = integral proteins

Question 7

Cell-cell junctions are comprised of proteins that allow cells to recognize each other & contribute to cell differentiation & development. These proteins are known as ?

Answer 7

CAM: cell adhesion molecules

Question 8

What are the different cell-cell junctions & how they do they carry out their functions ?

Answer 8

Gap (connexons formed from 6 connexin molecules): allow for direct cell-cell communication
Tight: prevent solutes from leaking into the space btwn cells by a paracellular route
Desmosomes: bind adjacent cells by adhering to their cytoskeletons
*Hemidesmosomes: attach epithelial cells to underlying structures (especially basement membrane)

Question 9

What are the 3 possible relationships between H20 & solute conc. via osmosis ?

Answer 9

Hypertonic: high solute conc. outside cell
Isotonic: equilibrium
Hypotonic: low solute conc. outside cell

Question 10

A physical property of solutions that is dependent on the conc. of dissolved particles but not on the identity of those particles is known as ?

Answer 10

Colligative property

Question 11

Simple diffusion for molecules that are impermeable to the membrane is known as ?

Answer 11

Facilitated diffusion

Question 12

What is the difference between pinocytosis & phagocytosis ?

Answer 12

Pino is related to fluids & dissolved particles, while phago is related to large solids