Quiz 4 - Cells

Question 1

What are the two general types of membrane transport

Answer 1

• Passive
• Active

Question 2

What is passive transport?

Answer 2

• No energy required for movement of substances down concentration gradients (high to low) across membrane

Question 3

What is active transport?

Answer 3

• Energy, in the form of ATP, required to move substances AGAINST gradients (low to high) across membrane

Question 4

What is simple diffusion and what kind of substances can pass through it?

Answer 4

• The movement from High to Low concentration (no energy needed)
• Nonpolar substances, hydrophobic, some gases

Question 5

What is facilitated diffusion?

Answer 5

-Diffusion through PROTEINS
-Channels and carrier proteins move specific molecules across cell membrane
-No energy needed (high to low)

Question 6

What is a carrier protein?

Answer 6

• alternates between two conformations, moving a solute across the membrane as the shape of the protein changes

-can transport the solute in either direction

-down the gradient

Question 7

What kind of substances pass through by facilitated diffusion?

Answer 7

Polar, hydrophillic

Question 8

What is Osmosis?

Answer 8

• Diffusion of water from high conc of water to low conc of water across a semi-permeable membrane

Question 9

What are aquaporins?

Answer 9

Water channels, allowing water to move rapidly into and out of cells

Question 10

Explain Ion (electrogenic Pumps)

Answer 10

• proteins that generate voltage across a membrane
• in animal cells: SODIUM/POTASSIUM PUMP
• in plants,fungi,bacteria: proton pump

Question 11

What is the electrochemical gradient

Answer 11

• 2 forces:
  1) Chemical: conc gradient
  2) Electrical: charge diff across membrane favours movement of cations in and anions out.

Question 12

Explain how the sodium-potassium pump works

Answer 12

• Type of active transport system that moves 3 Na+ ions out for every 2 K+ ions it pumps into the cell.
  -Requires ATP

Question 13

Explain how the proton pump works

Answer 13

• Actively transports protons out of cell, thus transferring positive charge
• Cytoplasm to extracellular fluid (requires ATP)

Question 14

What is co-transport?

Answer 14

• occurs when active transport of a specific solute indirectly drives the active transport of another solute
• involves transport by a membrane protein
• driven by a conc gradient (ATP required)

Question 15

What is the difference between antiport and symport?

Answer 15

antiport can move particles in different ways (opp direction), whereas symport can only do it in one direction

Question 16

What is bulk transport?

Answer 16

• Moving large molecules into and out of cell through vesicles and vacuoles
• Consists of endocytosis and exocytosis

Question 17

What is endocytosis and what does it consist of?

Answer 17

• the ingestion of large molecules in small vesicles

CONSISTS:
-phagocytosis
-pinocytosis
-receptor-mediated endocytosis

Question 18

What happens during phagocytosis?

Answer 18

-pseudopods extend from cell membrane and engulf particles; enter cell via membrane-bond sac
-fuse with lysosome for digestion

Question 19

what happens during pinocytosis?

Answer 19

-extracellular fluid and dissolved solutes enclosed in vesicle and brought into cell
-non specific process

Question 20

what happens during receptor-mediated endocytosis?

Answer 20

-coated pit regions of membrane contain receptors that bind extracellular substances
-material engulfed in vesicle
-receptors recycled back to membrane
-triggered by molecular signal

Question 21

What is exocytosis?

Answer 21

-The release of cellular material into the extracellular fluid
-Accomplished by fusing of vesicles with the plasma membrane