Unit II

Question 1

Passive Transport/Diffusion

Answer 1

particles moving from a higher gradient to a lower gradient, dose NOT use ATP

Question 2

Active Transport

Answer 2

against gradient, energy must be extrated from ATP

Question 3

Lipid/Fat Soluble substances that can diffuse through the cell membrane:

Answer 3

Substance must be lipid-soluble or polarized/electrically neutral

• oxygen
• carbon dioxide
• nitrogen
• alcohol

Question 4

Selectively permeable for size, shape, and/or electrical charge

Answer 4

Protein Channel

Question 5

More leaky, Na+ leak channels or K+ leak channels?

Answer 5

K+ leak channels are MORE leaky then Na+

Question 6

Ligand (Chemical) Gated Channels

Answer 6

a chemical messenger, ligand, binds to the receptor site, the channel stays open until the ligand is removed from the receptor site

Question 7

Voltage-Gated Channels

Answer 7

activated/open by changes in the electrical charge across the cell membrane

Question 8

Two types of gated channels:

Answer 8

Ligand-gated channels and voltage-gated channel

Question 9

FAST Voltage-gated Na+ Channel

Answer 9

• activated when the cell membrane is -60mV
• channel is lined with negative charges
• close when the cell membrane is +20mV

Question 10

SLOW Voltage-Gated K+ Channel

Answer 10

• take until +20mV for the channel to open

- closes when the cell returns to resting membrane state (-90mV)

Question 11

Facilitated Diffusion (Carrier Mediated Diffusion)

Answer 11

• still a PASSIVE process
• have a tendency to become saturated
  ex. glucose transporters
• glucose enter partway through the channel and then opens up on the other side
• insulin is NOT the glucose transporter, but in some cells it regulates the transporters

Question 12

Insulin Independent Glucose Transporters

Answer 12

• neurons and the nervous system
• hepatocytes in the liver (insulin does ^ transport)
• proximal tubules of kidney
• small intestine
• exercising skeletal muscle fibers requries less insulin then resting skeletal muscle fibers

Question 13

Factors that affect the rate of glucose transport diffusion:

Answer 13

Increase Diffusion:

• increased surface membrane area
• thinner the membrane permeability
• more permeable
• larger gradient
• more lipid-soluble
• more protein channels
• increased temperature
• increased gradient across the membrane

Question 14

Membrane gradients that affect rate of diffusions:

Answer 14

• concentration gradient
• electrical gradient
• pressure gradient
• usually a combination

Question 15

Secondary Active Co-Transport is only seen in TWO places:

Answer 15

1. Small Intestine

2. Proximal Tubules of the Kidney

Question 16

Where does Secondary Active Counter-Transport take place?

Answer 16

Renal tubules of kidney

Question 17

Endocytosis

Answer 17

• active transport mechanism
  1. Pinocytosis
  2. Phagocytosis