Bio Test 2a

Question 1

what make up the neuron

Answer 1

cell body, axon, terminals and dendrites

Question 2

three conformations of Na+ Channel

Answer 2

closed
open
inactivated

Question 3

closed Na+ channel

Answer 3

polarized membrane, resting state, maintain membrane potential, -60 mV

Question 4

opened Na+ channel

Answer 4

membrane depolarized, Na+ flows in, -60 mV to 40 mV

Question 5

inactivated Na+ channel

Answer 5

allows channel to desensitize and not respond to second signal, if opened then could depolarize membrane more and damage cell

Question 6

what causes an action potential

Answer 6

depolarization of plasma membrane from -60 mV to -40 mV, mediated by voltage-gated Na+ channel

Question 7

propagation of action potentials

Answer 7

action potential travels away from site of depolarization, one direction only, movement of electrical signal

Question 8

synapse

Answer 8

specialized junctions between the transmitting and receiving cells

Question 9

voltage-gated Ca2+ channel

Answer 9

regulated by membrane potential

Question 10

electrical signals are converted to…

Answer 10

chemical signals

Question 11

neurotransmitter

Answer 11

small signaling molecule that converts an electrical signal to a chemical signal

Question 12

where are neurotransmitters stored?

Answer 12

synaptic vesicle

Question 13

what triggers the release of neurotransmitters?

Answer 13

the voltage-gated Ca2+ channels

Question 14

where does the conversion of electrical signal to chemical signal happen?

Answer 14

at the nerve terminals to relay the signal to the target cells

Question 15

process of converting chemical signal back to electrical

Answer 15

neurotransmitter diffuses across synaptic cleft
neurotransmitter binds to neurotransmitter receptor concentrated in postsynaptic membrane
transmitter-gated ion channels open
action potential generated on target cell

Question 16

excitatory neurons

Answer 16

cause postsynaptic cell to fire an action potential

Question 17

excitatory neurotransmitters

Answer 17

acetylcholine
gultamate
serotonin

Question 18

receptors for excitatory signals allow what two ions to pass?

Answer 18

Na+

Ca2+

Question 19

inhibitory neurons

Answer 19

prevent postsynaptic cell from firing

Question 20

strychnine

Answer 20

causes muscle spasms by blocking inhibitory signals

Question 21

curare

Answer 21

relaxes muscle by blocks excitatory signals

Question 22

inhibitory neurotransmitters

Answer 22

GABA

glycine

Question 23

receptors for inhibitory signals allow what ions through?

Answer 23

Cl-

Question 24

neurotransmitters are major targets for what?

Answer 24

psychoactive drugs

Question 25

What binds to GABA-gated Cl- channels?

Answer 25

barbiturates | tranquilizers

Question 26

What neurotransmitter's reuptake is blocked by an antidepressant?

Answer 26

serotonin

Question 27

What are the four ways of cell communication?

Answer 27

endocrine paracrine neuronal contact-dependent

Question 28

endocrine

Answer 28

long distance uses hormones as communication tool and are long-lived through the circulatory system

Question 29

paracrine

Answer 29

``` short distance (ex. growth factor) short-lived and have local effect might influence back to signaling cell, process called autocrine coordinate activities of neighboring cells ```

Question 30

neuronal

Answer 30

specific to nervous system signal molecules are neurotransmitters short-lived happens over a synapse

Question 31

contact-dependent

Answer 31

membrane proteins on contacting cells | between 2 adjacent cells

Question 32

intracellular receptors

Answer 32

smal hydrophobic signal molecules (hormones) | signal receptor complex enters nucleus and binds DNA

Question 33

what does the intracellular receptor NO do?

Answer 33

it cause the relaxation of smooth muscle cells

Question 34

what are the two types of intracellular receptors?

Answer 34

``` hormones Nitric oxide (NO) ```

Question 35

what are the three classes of cell surface receptors?

Answer 35

ion-channel-coupled receptors G-protein-coupled receptors enzyme-coupled receptors

Question 36

ion-channel-coupled receptors

Answer 36

ion channel and receptor

Question 37

what is a coupled receptor?

Answer 37

receptor that is also something else at the exact same time

Question 38

G-protein-coupled receptors

Answer 38

G-protein and receptor are completely separate but associate with each other

Question 39

enzyme-coupled receptors

Answer 39

a receptor that is also an enzyme at the same time

Question 40

characteristics of a signal cascade

Answer 40

``` binding of signal and receptor receptor pases the signal to intracellular signaling molecules signal amplification integration or divergence of signals trigger fast and/or slow responses ```

Question 41

what are two common mechanisms that amplify signals?

Answer 41

phosphorylation | GTP-GDP

Question 42

responses to a signal cascade

Answer 42

the cell survives the grows and divides the cell differentiates (gains a specialized function) the cell dies

Question 43

signal cascade

Answer 43

``` extracellular signal molecule receptor protein intracellular signaling molecules effector proteins cell responses ```

Question 44

why are cellular responses fast or slow?

Answer 44

When the response is fast, the receptor just changes the proteins function and cell structure, but when the response is slow, the receptor goes through the nucleus, binds to DNA and begins active transcription.

Question 45

activation of intracellular molecules can be done in what two ways?

Answer 45

phosphorylation | GTP-binding protein

Question 46

activation of intracellular molecules through phosphorylation

Answer 46

protein kinase is an enzyme that changes ATP to ADP by losing a phosphate group, then after the target cell has received signal, protein phosphatase removes the phosphate

Question 47

activation of intracellular molecules by GTP-binding protein

Answer 47

has binding site for GDP and GTP, takes off GDP and replaces with GTP through GTP binding, and after signal is received, GTP hydrolysis removes a phosphate to return it to GDP

Question 48

G-protein coupled receptors

Answer 48

- typical 7-pass transmembrane proteins - 3 domains: transmembrane intracellular extracellular - primarily for: vision, smell, taste and chemoreception

Question 49

G-protein

Answer 49

- 3 subunits or heterotrimer - alpha subunit binds GDP and GTP - breaks into two signaling units upon activation aplha and beta/lamda signaling units

Question 50

G-protein coupled receptor process

Answer 50

- an inactive g-protein comes into contact with transmembrane protein - the signal molecule signals the protein and the G-protein activates - protein breaks into two subunits through GTP binding - the beta/lambda complex comes to the channel and signals it to open - the alpha complex then goes through hydrolysis - the three subunits then reconnect an return to inactivated state