L14-16: Signal transduction+ molecular signaling

Question 1

what are the 2 factors that influence a cell’s membrane potential?

Answer 1

1. the electrical concentration gradients of different ions across the membrane
2. the permeability of the membrane to these ions

Question 2

the direction of change: depolarization

Answer 2

membrane potential becomes less negative (toward 0)

Question 3

direction of change; repolarization

Answer 3

bring back to resting membrane

Question 4

direction of change: hyperpolarization

Answer 4

more polarized than b4 (even more negative)

Question 5

function: receptor potential (local)

Answer 5

activated by receptors (Na+ receptor channel)
-depolarization & hyperpolarization

Question 6

function: synaptic potential (local)

Answer 6

post-synaptic as a result of synaptic activity
-depolarization

Question 7

function: action potential

Answer 7

happen at axon, involved in a change in membrane potential

Question 8

Electrical synapses

Answer 8

direct electrical connection
-ions flow thru gap junction channels (connexons)

Question 9

chemical synapses

Answer 9

neurotransmitter released
ions flow thru synaptic channels

Question 10

what are the criteria that define a neurotransmitter?

Answer 10

1. must be present in the presynaptic neuron
2. must be released in response to presynaptic depolarization & release must be calcium-dependent
3. specific receptors for the substance must be present on the postsynaptic cell

Question 11

3 types of chemical signaling mechanisms

Answer 11

1. synaptic (shortest)
2. paracrine
   -responses to allergens
   -tissue repair
   -the formation of scar tissue
   -in brains- neuropeptides
3. endocrine (longest)
   hormones

Question 12

3 types of cell signaling molecules

Answer 12

1. cell-impermeant
   -transmembrane receptors
2. cell-permeant (steroid, hormones)
   -intracellular receptor
3. cell-associated molecules
   -receptors

Question 13

channel-linked receptors

Answer 13

ion channels gated by a ligand
1. signal (ligand) binds
2. channel opens
3. ions flow membrane

Question 14

enzyme-linked receptors

Answer 14

1. signal binds
2. enzyme activated
3. enzyme generates product

Question 15

G-protein-coupled receptors

Answer 15

1. signal binds
2. g-protein binds
3. g-protein activated

Question 16

intracellular receptors

Answer 16

1. signal binds
2. activated receptor regulates transcription

Question 17

Fluorescence Resonance Energy Transfer (FRET)

Answer 17

low Ca+: cyan (absorption)
high Ca+: yellow (emission)
form when the emission overlaps the absorption
one molecule excites the other thru absorption thru light