8 cell communication

Question 1

signal transduction

Answer 1

changing the form of a signal, either by releasing another chemical signal or binding to another cellular component

Question 2

typical communication between cell

Answer 2

signalling cell produces extracellular signal molecule detected by target cell

Question 3

target cell

Answer 3

have receptor proteins that recognize and respond to signal molecule and convert (signal transduction) to intracellular signaling molecules

Question 4

cell signaling

Answer 4

signal reception and transduction (transmission from exterior to interior of cell)

Question 5

examples of signal molecules

Answer 5

• proteins
• peptides
• amino acids
• nucleotides
• steroids
• fatty acid derivatives
• dissolved gases

Question 6

types of signals (4)

Answer 6

• endocrine signaling –> broadcasting on radio
• paracrine signaling –> sending flyer to select people
  
  • -> autocrine signaling –> writing reminder to yourself
• neuronal signaling –> phone call, long distance, but specific
• contact-dependent signaling –> in person

Question 7

endocrine cells

Answer 7

cells that produce hormones

Question 8

autocrine signaling

Answer 8

example of paracrine signal that respond to local mediators that they themselves produce

Question 9

mating factor

Answer 9

small protein secreted when yeast cell ready to mate

is detected by the opposite sex as chemical mating call

Question 10

neuronal signaling

Answer 10

neurons deliver message over long distance, but quickly and specifically to individual target cells.

Question 11

neurotransmitter

Answer 11

an extracellular signal molecule from an electrical pulse from nerve terminal

Question 12

paracrine signaling

Answer 12

diffuse signal molecule locally in the neighbourhood of the cell that produced signal

Question 13

hormone

Answer 13

secreting signal molecule, into blood stream, broadcasting to entire body

Question 14

contact dependent signaling

Answer 14

• intimate, short range communication

- no secreted molecule, instead direct physical contact of embedded receptor proteins

Question 15

response to signal

Answer 15

• receptors only hear and respond to one type of signal, and are deaf to all other signals
• many receptors accept the same signal molecule, but is interpreted differently by target cells

Question 16

types of extracellular signal molecules

Answer 16

• molecules too large or too hydrophilic to pass through membrane, use receptors on the surface of target cells
• molecules smaller, and more hydrophobic enough to pass into cytosol and bind to receptor proteins
• -> eg. steroid hormones; cortisol, estradiol, testosterone, thyroxine are hydrophobic that pass through membrane and bind to receptor proteins located in cytosol or nucleus

Question 17

nuclear receptors

Answer 17

protein receptors located in nucleus or cytosol that are activated by signal molecules binding to the receptor which them changes the conformation

Question 18

cortisol hormone example

Answer 18

cortisol hormone produced by adrenal gland crosses plasma membrane and binds to receptor protein which activates and enters nucleus through nuclear pore and binds to DNA and activates transcription of specific genes

Question 19

ligand

Answer 19

a signal molecule, hormone

Question 20

g-protein

Answer 20

protein attached to cytosolic side of membrane that binds to transmembrane protein that has changed conformation becomes activited and binds to enzyme that will change conformation and releasing another signal molecule cAMP (cyclic amp) that will elicit a cellular response

Question 21

second messengers

Answer 21

cAMP, different molecules from the initial ligand that amplify and carry the same signal

Question 22

phosphorylation cascade

Answer 22

when a signal molecule binds to protein that changes conformation and releases relay molecule, it interacts with intercellular proteins that exchange phosphate groups in a chain reaction, and then eventually reach the target cell, that will elicit a cellular response

Question 23

receptor mediated endocytosis

Answer 23

• when bulk quantities of signal molecules are accepted by receptors
• the signal molecule as a substrate bind to the receptors that buds off into a vesicle along with any additional solute that enters

Question 24

intercellular receptor

Answer 24

found in cytoplasm or nucleus, the signal molecule (ligand) must be able to pass through membrane, if small and non polar, and activate it
- can later enter nucleus and act as a transcription factor

Question 25

types of cellular responses

Answer 25

- gene activation or inactivation (if icr enters nuclear) - metabolic influence (activate enzyme that breaks down stored glycogen) - initiation or halting of cell division - -> malfunction can cause cancer, as regulates cell division

Question 26

receptors

Answer 26

- either in membrane or inside of cell - specifc ligands (substrates) that fit in the active sites - will change conformation that will initiate cellular response

Question 27

single pass receptor

Answer 27

is a cell surface receptor with one alpha helix transmembrane - -> receptor tyrosin kinase - -> protein tyrosin phosphate - -> protein serine/thyreonine kinase

Question 28

plasmodosmata

Answer 28

gap junctions where two plant cells overlap and send signal molecule (ligands)

Question 29

intracellular signaling pathways

Answer 29

- relay signal onward - amplify signal received to smaller messengers - integrate multiple signaling pathways and relaying - distribute signal to effector proteins that evoke cellular response

Question 30

signaling by protein phosphorylation

Answer 30

phosphate covalently added by protein kinase that transfers terminal phoshate group from ATP to signaling protein

Question 31

gtp binding protein

Answer 31

exchange gdp to gtp to recieve signal and switch back to gdp by hydrolyzing to release signal

Question 32

gefs

Answer 32

guanine nucleotide exchange factors promote exchange of gdp for gtp by switching on gtp binding protein on.

Question 33

gtpase activating proteins

Answer 33

stimulate hydrolysis of gtp to gdp switching off gtp binding protein off

Question 34

three classes of cell surface receptors

Answer 34

- ion channel coupled receptors change permeability of membrane potential and produce electric current

Question 35

g protein coupled receptors

Answer 35

activate membrane bound trimeric gtp binding proteins that activate enzyme or ion channel in membrane