CH 12

Question 1

What molecules diffuse faster

Answer 1

small hydrophobic nonpolar

Question 2

Channels v Transporters

Answer 2

Channels allow molecules of appropriate diffuse to passively diffuse

Transporters allow passive diffusion of specific molecules or ions

Question 3

Osmosis

Answer 3

Water moving down its gradient
Based on conc. of solutes

Question 4

Aquaporins

Answer 4

channels that allow water to passively diffuse

Question 5

How do Protozoan, Animal cells, and Plant cells deal with too much intracellular water

Answer 5

Protozoan - expelling water vacuoles

Animal Cells - Diffusion

Plant Cells - Creates vacuoles to reinforce cell wall (turgor pressure)

Question 6

Na+ Pump Function

Answer 6

Pumps out Na+ and K+ into cell
process done with ATP

Question 7

What drives the transport of solutes in Plants, Bacteria and Fungi

Answer 7

H+ pumps

Question 8

What drives the concentration of glucose across animal cells

Answer 8

Na+ gradient

Question 9

Pumps:

Answer 9

Actively transport a solute across its gradient

Question 10

Na+ and K+ concentrations

Answer 10

K+ high in cell
Na+ high outside cell

Question 11

Differences in concentrations of ions across cell creates what

Answer 11

Membrane potential - difference in charge across membrane

Question 12

Na+ Pump process

Answer 12

Pump phosphorylized
Changes conformation releasing Na
K Binds
Dephosphorylated
Changes conformation releasing K inside cell

Question 13

Ca Pump

Answer 13

keeps Ca levels low inside cell

Ca can cause a lot of interactions so needs to be regulated

Question 14

Symport vs Antiport

Answer 14

Symport - energy providing molecule and molecule go in same direction

Antiport - energy providing molecule and molecule go in opposite directions

Question 15

What drives the transfer of glucose across cells?

Answer 15

electrochemical Na+ gradient

Question 16

Gut epithelial cell example

Answer 16

Na+ symport takes glucose in with Na+ from Gut Lumen

Glucose passively diffuses out to extracellular fluid

Na+ is pumped out in the Na+ pump to take K+ in

Question 17

Ion Channels are _____ & ________

Answer 17

Ion-selective & gated

Question 18

K+ selectivity filter

Answer 18

K+ can fit through despite being larger than Na+ because it is dehydrated

Na+ is not dehydrated so it is not energetically favorable

Question 19

Ion channel conformations

Answer 19

Open and Closed

Question 20

Membrane Potential Is Governed by…

Answer 20

the Permeability of a
Membrane to Specific Ions

Question 21

When K+ leak channels allow K+ to diffuse out the cell, what does this do?

Answer 21

create membrane potential

Question 22

Na+ Pump charge differences

Answer 22

Pumps 3 Na+ out, 2 K+ in

HELPS make inside of cells more negative

Question 23

Patch clamp technique

Answer 23

Method to measure ion channel activity

Question 24

How does acetylCholine affect channels

Answer 24

Opens and closes faster

Question 25

4 types of gated channels

Answer 25

Mechanically Ligand gated (extracellular and intracellular) Voltage-Gated

Question 26

Mechanically gated channels:

Answer 26

respond to physical stress by tilting the channel with a filament, causing it to open i.e. Helps us hear, venus flytraps detect prey

Question 27

Voltage gated channels Structure/Function

Answer 27

Has voltage sensors sensitive to membrane potential change Causes open state when threshold reached

Question 28

Axon resting potential is

Answer 28

-60mv (more negative than positive)

Question 29

Axons vs dendrites

Answer 29

Axons conduct signals away from cell body Dendrites receive signals from other axons of other cells

Question 30

what happens to membrane potential when neuron is stimulated

Answer 30

Will become depolarized (value closer to 0)

Question 30

what does depolarization do to a ion gate

Answer 30

Allows Na+ channels open transiently Na+ further depolarizes the membrane to 40+mv

Question 31

Neuron resting potential value First depolarization value to open Na+ Gates Peak action potential value

Answer 31

-60 mv -40 mv +40 mv

Question 32

How does depolarization help open an ion gate

Answer 32

positive charges on the gate attract to negative ones and twist to expose themselves to the negative charges, opening the gate

Question 33

How far does an action potential travel along an axon? What direction?

Answer 33

The whole length Only goes forwards because the inactive state prevents the potential from going back.

Question 34

How do voltage gated K+ channels fit into action potentials

Answer 34

restores K+ concentrations and membrane potential to resting potential.

Question 35

Most energy used by the brain is used to what

Answer 35

Power Na+ pumps that restore membrane potential

Question 36

Synaptic vesicles

Answer 36

store neurotransmitters

Question 37

How do synaptic vesicles release neurotransmitters

Answer 37

Ca2+ binds to proteins on the vesicles causing them to fuse to the plasma membrane and release them into the Cleft.

Question 38

Where does the action potential reach?

Answer 38

Triggers voltage gated Ca2+ channels in presynaptic nerve terminal.

Question 39

where do neurons connect to target cells

Answer 39

Synapses

Question 40

Acetylcholine receptor structure

Answer 40

5 subunits, 2 identical ones

Question 41

Excitatory neurotransmitters examples

Answer 41

glutamate, acetylcholine - depolarizes membrane

Question 42

Inhibitory

Answer 42

(GABA) and glycine – opens Cl- channels and Cl- enters the cell inhibiting postsynaptic membrane from depolarizing