Membrane transport

Question 1

Active transport

Answer 1

requiring energy and ATP

Question 2

Passive transport

Answer 2

no energy required

Question 3

Concentration

Answer 3

the amount of solute (substance) in a solvent (liquid)

Question 4

Concentration gradient

Answer 4

more solute in one part of a solvent than another

Question 5

Diffusion

Answer 5

-a function of the concentration gradient
-molecules mix randomly
-solute spreads through solvent
-eliminates concentration gradient
-solutes move down a concentration gradient

Question 6

Factors affecting diffusion

Answer 6

• distance
• molecule size
• temperature
• gradient size
• electrical forces

Question 7

Simple diffusion

Answer 7

• diffuse through plasma membrane
• lipid-soluble compounds (alcohols, fatty acids, and steroids)
• dissolved gases (oxygen and carbon dioxide)

Question 8

Osmosis

Answer 8

• the diffusion of water across the cell membrane
• water molecules diffuse across the membrane toward the solution with more solutes

Question 9

Osmotic pressure

Answer 9

• the force of a concentration gradient of water
• equals the force (hydrostatic pressure) needed to block osmosis
• no osmosis

Question 10

Hypotonic

Answer 10

• swells
• less solutes and loses water through osmosis

Question 11

Hypertonic

Answer 11

• shrivels
• more solutes and gains water by osmosis

Question 12

Carrier-meditated transport

Answer 12

*- carrier-mediated transport of ions and organic substrates
- facilitated diffusion
- active transport
* characteristics
- Specificity : one transport protein, one set of substrates
- Saturation limits: rate depends on transport proteins, not substrate
- Regulation: cofactors such as hormones

Question 13

Facilitated diffusion

Answer 13

• passive
  Carrier proteins transport molecules too large to fit through channel proteins (glucose, amino acids):
• molecules bind to receptor site on carrier protein
• protein changes shape, molecules pass through
• receptor site is specific to certain molecules

Question 14

Active transport

Answer 14

• move substrates against concentration gradient
• require energy, such as ATP
• ion pumps move ions (Na+, K+, Ca2+, Mg 2+)
• exchange pump countertransports two ions at the same time

Question 15

Sodium-potassium exchange pump

Answer 15

• active transport
• carrier mediated
• sodium out, potassium in
• 1 ATP moves 3 Na & 2K

Question 16

Vesicular transport (or bulk transport)

Answer 16

-materials move into or out of the cell in vesicles
- endocytosis ( active transport using ATP)
- exocytosis

Question 17

Pinocytosis

Answer 17

Endosomes “drink” extracellular fluid

Question 18

Phagocytosis

Answer 18

Engulf large objects in phagosomes