Cell Memebrane & Transportation study guide

Question 1

What is the function of a cell membrane

Answer 1

(gatekeeper) allows substances to enter and exit through the membrane

Question 2

what does selectively permeable mean?

Answer 2

Allows certain substances to pass, but does not to specific substances

Question 3

what factors determine whether a molecule can enter a cell or not

Answer 3

• size
• shape
• polarity
• chemical composition

Question 4

what are the 3 general means by which substances can enter cells?

Answer 4

diffusion, osmosis and active transport

Question 5

compare and contrast in terms of: 
 [ ] gradient 
energy requirements
types of molecules transported 
- diffusion
- osmosis
- facilitated transportation
- active transport
- phagocytosis 
- pinocytosis
- endocytosis
- receptor mediated endocytosis
- exocytosis

Answer 5

diffusion
osmosis
facilitated transportation
active transport
phagocytosis 
pinocytosis
endocytosis
receptor mediated endocytosis
exocytosis

Question 6

How does the cell membrane’s structure help in the transportation mechanisms for

• diffusion
• osmosis
• facilitated transportation
• active transport
• phagocytosis
• pinocytosis
• endocytosis
• receptor mediated endocytosis
• exocytosis

Answer 6

diffusion
osmosis
facilitated transportation
active transport
phagocytosis 
pinocytosis
endocytosis
receptor mediated endocytosis
exocytosis

Question 7

ways to increase/decrease diffusion rates

Answer 7

• temperature
• size
• [ ] gradient

Question 8

what is cytoplasmic streaming and how does it help with diffusion

Answer 8

• the movement of the fluid substance (cytoplasm) within a plant or animal cell
• allows movement of substances from a high [ ] to a low [ ] to speed up

Question 9

what is osmotic pressure and hydrostatic pressure and what is their inter-relationship between these two pressures

Answer 9

osmotic pressure: pressure exerted on membrane due to the flow of water

hydrostatic pressure: pressure due to the weight of liquid pushing back

• if osmotic pressure occurs, hydrostatic pressure will occur to create an eq’m

Question 10

what is the effect of an isotonic/hypertonic/hypotonic solution on an animal or plant cell?

Answer 10

Isotonic: remains the same

Hypertonic:

• Animal cell: Crenated (shrivels up)
• Plant cell: Plasmolysis (cell wall maintains shape of cell but contents insides shrivel up)

Hypotonic:

• Animal cell: Hemolysis (causes cell to expand, possibly making it explode)
• Plant cell: Turgor pressure (cell wall stretches but does not lose shape, contents inside expand, causing pressure to be created due to exerted by wall)

Question 11

provide examples of active transport in the body

Answer 11

• I+ ions from blood to thyroid gland

- Na+/K+ pump

Question 12

types of proteins and their functions

Answer 12

Channel protein: allows particular molecules or Ions to pass through cell membrane freely based on size

Carrier protein: selectively interacts with a specific molecule or Ion so that it can pass through cell membrane (usually requires ATP)

Receptor protein: used to allow a specific molecule to bind to it

Cell recognition protein: used to identify if celll is foreign to body

enzymatic protein: speeds up a chemical reaction