BSCI330 cellular communication

Question 1

how do cells communicate withe each other

Answer 1

via receptors, which bind to signal molecule ligands

Question 2

what is the difference between hydrophobic and hydrophilic ligands

Answer 2

hydrophobic ligands can cross membranes to activate intracellular receptors while hydrophilic ligands have to bind to cell-surface transmembrane receptors

Question 3

what do second messengers do

Answer 3

transmit the signals from the cell surface to the effectors, which is required by signal transduction from cell-surface receptors

Question 4

what are the 3 basic modes of signaling

Answer 4

ion channels, enzyme-coupled receptors, G-protein-coupled receptors

Question 5

what are the 3 general cell communication steps

Answer 5

reception, transduction, response

Question 6

what is paracrine signaling

Answer 6

affect only cells in the immediate environment of the signaling cell

Question 7

what is endocrine signaling

Answer 7

travel long distances through the bloodstream to act on distant targets

Question 8

what is synaptic signaling

Answer 8

travel via axons

Question 9

what is autocrine signaling

Answer 9

a cell secretes signal molecules that can bind back to its own receptors

Question 10

what is contact-dependent signaling

Answer 10

bound to surface of cell so have to have cell-to-cell contact and only influence cells that contact it

Question 11

what happens when a cell doesn’t receive specific combination of signals

Answer 11

cell activates apoptosis

Question 12

what do cell responses vary according to

Answer 12

unique collection of receptor proteins

the intracellular signaling machinery by which the cell integrates and interprets what it receives

Question 13

what do morphogens do

Answer 13

diffuse out from signaling centers in developing tissues, creating a morphogen concentration gradient

Question 14

what are the types of cell signals

Answer 14

mechanical: adhesion to substrates, membrane distortion, sound

light

heat

chemical

Question 15

what can lipid soluble signals do

Answer 15

can diffuse across the plasma membrane
- steroid hormones and gaseous signaling molecules

travel to their target cells via carrier proteins

bind to intracellular receptors

Question 16

what are hydrophilic/lipid insoluble signals

Answer 16

polar, water soluble molecules

neurotransmitters, peptide hormones, growth factors

cannot cross cell membranes and must bind to sites on cell surface receptors

Question 17

what are the 3 major types of cell surface receptors

Answer 17

ligand-gated ion channels, enzyme coupled receptors, G-protein coupled receptors

Question 18

what are ligand-gated ion channels

Answer 18

binding to ligands causes channel to open and allows specific ions to flow through

Question 19

what are enzyme-coupled receptors

Answer 19

activate an enzyme when activated

Question 20

what are G-protein coupled receptors

Answer 20

activation of receptor causes a change in GTP vs GDP binding of a switch protein, which turns downstream enzymes on or off

Question 21

what is a kinase cascade

Answer 21

passing down phosphorylation of kinases

Question 22

what are first messengers

Answer 22

cell-surface receptors that carry the signal across plasma membrane

Question 23

what do second molecules do

Answer 23

combination of activated enzymes and small intracellular molecules called second molecules amplify the signal and spread it throughout the cell

Question 24

what do effector proteins do

Answer 24

regulate cell’s response

Question 25

what intracellular signaling proteins function as molecular switches activated by kinases/phosphatases

Answer 25

phosphorylation/dephosphorylation, GTPases, GTP-binding proteins

Question 26

what are signaling complexes

Answer 26

regulate speed, efficiency, and specificity of a cellular response

organized around a scaffold protein or assembled following receptor activation or assembled on phosphorylated phosphoinositide lipids

Question 27

what is Ras

Answer 27

on/off switching signaling protein - bound to GTP, released from protein when bound to GDP

initiates phosphorylation cascade

Question 28

what is the role of calcium as an intracellular messenger

Answer 28

has a key role in muscle contraction, cell division, fertilization, metabolism