Cell Transport and Permeability

Question 1

Passive Transport

Answer 1

• uses kinetic energy
• high to low concentration (down concentration gradient)
• speed of diffusion based on size, temp and concentration

Question 2

Simple diffusion

Answer 2

• diffuse directly through layer
• fat soluble can pass through
• ex. gases, steroid hormones, fatty acids

Question 3

Facilitated diffusion

Answer 3

• uses transmembrane proteins, as carriers or channels
• used for substances that cant pass layer
• limited

Question 4

Carrier-mediated facilitated diffusion

Answer 4

• transport polar molecules or classes of molecules (sugars, aa)
• protein changes shape to move binding site
• limited (saturable)

Question 5

Channel-mediated facilitated diffusion

Answer 5

• transport substances (ions or h2O)
• channels open and close
• limited (saturable)

Question 6

leakage channels

Answer 6

• always open
• move according to concentration gradient
• limited (saturable, bcos of limited channels)

Question 7

gated channels

Answer 7

• controlled by chemical or electrical signals

- limited (saturable, bcos of limited channels)

Question 8

Osmosis

Answer 8

• diffusion of solvents (specifically h2O)
• diffuses until concentration of water is same on both sides
• solutes cannot move through layer

Question 9

Osmolarity

Answer 9

• total concentration of solute particles in solution

Question 10

Tonicity

Answer 10

• cell experiences net gain or loss of water

- ability for solution to change cell shape by osmotic flow

Question 11

isotonic

Answer 11

• same concentration of solutes inside and outside of cell
• no gain or loss of water
• no cell shape change

Question 12

Hypertonic

Answer 12

• more solute concentration inside than outside
• cell lose water and shrivel
• water moves into hypertonic solution, so cell loses water

Question 13

Hypotonic

Answer 13

• less solute concentration inside than outside
• cell gains water and swells
• hypotonic solution loses water
• if there are no solutes in extracellular solution, cell can rupture

Question 14

Hemolysis

Answer 14

• RBC placed in distilled water

- they rupture as water floods into them

Question 15

Benedicts test

Answer 15

• tests presence of glucose
• if present, turns different color or creates precipitate
• solution stays blue = negative

Question 16

AgNO3 test

Answer 16

• presence of sodium chloride (NaCl)

- forms white precipitate if present

Question 17

Active Transport

Answer 17

• needs ATP to occur
• for molecules or ions
• moves against concentration gradient

Question 18

primary active transport

Answer 18

• sodium-potassium pump (Na/K pump)
• 3 Na out
• 2 K in

Question 19

secondary active transport

Answer 19

• depends on ion gradient (primary active trans.)
• uses cotransport protein
• use Na to drag solutes into cell

Question 20

Endocytosis

Answer 20

• process of ingesting material
• uses cell membrane to envelop material
• portion turns into vesicles
• comes into cell to be digested and broken down

Question 21

Phagocytosis

Answer 21

• cell eating
• forms pseudopod
• psuedopod trap particles within phagosome
• phagosomes bind w/ lysosome

Question 22

Phinocytosis

Answer 22

• cell drinking
• endocytosis of fluids
• “gulps” fluid containing dissolved molecules into vesicle
• no receptors
• droplet fuses w/ endosome (sorting enzyme)

Question 23

receptor-mediated endocytosis

Answer 23

• specific/selective
• receptors are proteins that bind to specific substances
• cell ingest and concentrates them
• released inside cell or by lysosome

Question 24

Exocytosis

Answer 24

• eject substance from inside to outside
• stimulated by cell surface signal
• used for hormone secretion, neurotransmitter release, mucus secretion and ejection of water
• membrane and vesicle fuse and pore opens