cell communication

Question 1

autocrine signal

Answer 1

a cell targets itself; signal affects the cell secreting it

Question 2

signaling across gap junctions

Answer 2

a cell targets a cell connected by gap junctions

Question 3

paracrine signalling

Answer 3

a cell targets nearby cell

Question 4

example of paracrine signaling

Answer 4

synapse: paracrine signal causes neurotransmitter secretion

Question 5

endocrine signalling

Answer 5

a cell targets a distant cell through the bloodstream

Question 6

steps of responding to a signal

Answer 6

reception
transduction
response

Question 7

reception: signal molecules bind to

Answer 7

receptors; receptor does not move signal molecule, only connects to it

Question 8

signals are ligands, what is a ligand?

Answer 8

small molecules that bind to larger molecules

Question 9

membrane receptors location

Answer 9

-Partly inside and outside the membrane, making it a connection point between outside and inside of the cell.
-They detect signals outside the cell and make signals inside the cell
(Hydrophilic signals cannot pass through membrane)

Question 10

categories of membrane receptors

Answer 10

 G protein coupled
 Receptor tyrosine kinases
 Ion channel

Question 11

G protein coupled receptors have multiple

Answer 11

transmembrane regions

Question 12

G protein coupled receptors have an internal or external site for signal molecules?

Answer 12

external

Question 13

G protein coupled receptors have an internal connection to

Answer 13

G protein

Question 14

how are G protein coupled receptors activated?

Answer 14

by attaching GTP so that it can activate 1 cell process

Question 15

receptor tyrosine kinases energizes something by…

Answer 15

giving it ATP

Question 16

kinase:

Answer 16

transfer phosphate from ATP to give energy to another molecule to activate things

Question 17

how many tyrosine amino acids in receptor tyrosine kinases?

Answer 17

6 tyrosine amino acids, each can hold phosphate to form ATP

Question 18

ion channels:

Answer 18

channel that ions can pass through

Question 19

in ion channels, ions must move…

Answer 19

down concentration gradient

Question 20

intracellular receptors

Answer 20

found INSIDE cell (often in nucleus) and detects signals that can pass through cell membrane

Question 21

transduction definition

Answer 21

converting info from one form to another

Question 22

pathway:

Answer 22

series of interactions that accomplish something
-Each triggers the next like falling dominoes

Question 23

phosphorylation

Answer 23

take phosphate off ATP and give it to something

Question 24

phosphorylation cascades:

Answer 24

pathway of enzymes, and each adds phosphate to the next

Question 25

dephosphorylation

Answer 25

removes a phosphate group, deactivates enzyme, turns off pathways

Question 26

dephosphorylation is accomplished by

Answer 26

protein phosphatases

Question 27

where can response to a signal occur?

Answer 27

in cytoplasm (turns enzyme pathways on or off) or in the nucleus (turns genes on or off)

Question 28

response regulation: control mechanisms

Answer 28

signal amplification, different responses in different cells, pathway optimization, ending signal

Question 29

signal amplification:

Answer 29

*phosphorylation often occurs in cascades, where each step can activate multiple molecules of the next step.
*Small amount of signal can cause a large response, so you can control length of cascade to control signal.

Question 30

different responses in different cells:

Answer 30

*Receptor can be connected to different pathways
*Pathways determines cell behavior change
*Cells respond differently to same signal

Question 31

pathway optimization

Answer 31

*Pathway efficiency is determined by how close to each other steps are (where is B relative to A?)

Question 32

if proteins for each step are far apart, pathway is _____.

Answer 32

slower

Question 33

scaffolding proteins:

Answer 33

position pathway components in proper order to maximize pathway efficiency (holds protein A next to protein B)

Question 34

ending signal

Answer 34

Cell signal pathways must be inactivated when no longer needed

Question 35

when external signal becomes weak…

Answer 35

pathways are turned off

Question 36

apoptosis:

Answer 36

controlled cell suicide

Question 37

possible reasons for apoptosis:

Answer 37

-Cells only needed during one portion of development
-Cell damage
-Infected cells
-Cells no longer function properly