Chapter 2- Membrane Diffusion

Question 1

Simple Diffusion

Answer 1

-Flow of small, uncharged non-polar substances

(O2 and CO2) across cell membrane down the concentration gradient (high to low) WITHOUT using energy

Question 2

Osmosis

Answer 2

-simple diffusion that involves water molecules (water is polar, but small enough to cross membrane)

Question 3

Facilitated transport

Answer 3

• integral proteins allow large hydrophilic molecules to cross cell membrane.
• these proteins are: uniporters, symporters, antiporters

Question 4

Uniporters

Answer 4

-facilitated transport of single substance in one direction

Question 5

Symporters

Answer 5

-facilitated transport of two substances in the same direction

Question 6

Antiporters

Answer 6

-facilitated transport of two substances in the opposite direction

Question 7

Channel proteins

Answer 7

-open tunnels that face both sides of bilayer.

Question 8

Carrier Proteins

Answer 8

-binds to molecule on one side and changes shape to transport to the other side

Question 9

Passive diffusion

Answer 9

• type of facilitated transport that is done by channel proteins
• bringing molecules down their concentration gradient without energy use.
• Similar to simple diffusion but a channel protein is used.
• Ex: porins for hydrophilic molecules and ion channels for ions.

Question 10

Active Transport

Answer 10

-substances travel against their concentration gradient and require the consumption of energy by carrier proteins.

Question 11

Primary Active transport

Answer 11

• uses ATP hydrolysis to pump molecules against their gradient.
• Ex: Sodium-potassium (Na+/K+) pump

Question 12

Secondary active transport

Answer 12

-uses FREE energy released when other molecules flow down their concentration gradient to pump the desired molecule across the membrane.

Question 13

Cytosis

Answer 13

-the bulk transport of large, hydrophilic molecules across the cell membrane and requires energy.

Question 14

Endocytosis

Answer 14

• cell membrane engulfing an extracellular substance internalizing it
• via vesicle or vacuole

Question 15

Phagocytosis

Answer 15

-cellular EATING around solid objects

Question 16

Pinocytosis

Answer 16

-cellular DRINKING around dissolved materials (liquids)

Question 17

Receptor-mediated endocytosis

Answer 17

-requires the binding of dissolved molecules to peripheral membrane receptor proteins, which initiates endocytosis

Question 18

Exocytosis-

Answer 18

• material is RELEASED to the extracellular environment, via vesicle secretion
• opposite of endocytosis