Cell Signaling

Question 1

Signaling molecule

Answer 1

Ligand

Question 2

A molecule that ligands bind to

Answer 2

Receptor Protein

Question 3

What process does the binding of a ligand to a receptor protein initiate?

Answer 3

Signal Transduction

Question 4

Signaling cells that can also bind to the ligand that is released, such that signal and target cell can be the same/similar to each other; cell targets itself

Answer 4

Autocrine Signaling

Question 5

Intracellular mediators that allow small signaling molecules to move between cells; cell targets other cell connected by gap junctions

Answer 5

Direct Signaling Across Gap Junctions

Question 6

Move by diffusion through extracellular matrix (ex: synaptic signals and neurotransmitters; cell targets nearby cell

Answer 6

Paracrine Signaling

Question 7

Signals from distant cells that typically produce a slower response with long-lasting effect (ex: hormones); cell targets distant cell through bloodstream

Answer 7

Endocrine Signaling

Question 8

Why is autocrine signaling important?

Answer 8

Important for cell death

Question 9

When does autocrine signaling occur?

Answer 9

Early development

Question 10

What does autocrine signaling regulate?

Answer 10

Pain sensation

Question 11

What is direct contact signaling important in?

Answer 11

Early development

Question 12

What type of response does paracrine signaling initiate?

Answer 12

Quick and short-lived with local effects

Question 13

In what does paracrine signaling occur?

Answer 13

Animals

Question 14

What organisms use endocrine signaling extensively?

Answer 14

Animals and plants

Question 15

What type of receptor is located within a cell and bind with hydrophobic ligands that can easily cross the plasma membrane?

Answer 15

Intracellular Receptor

Question 16

What type of receptor is located on the plasma membrane to bind hydrophilic ligands outside the cell?

Answer 16

Cell Surface/Membrane Receptor

Question 17

Enzyme that adds a phosphate to a protein

Answer 17

Protein Kinase

Question 18

Enzyme that removes a phosphate from a protein

Answer 18

Phosphatase

Question 19

Channel-linked receptors that open to let a specific ion pass in response to a ligand

Answer 19

Chemically Gated Ion Channels/Ion Channel-Linked

Question 20

Receptor is an enzyme that is activated by the ligand; almost all are protein kinases

Answer 20

Enzymatic Receptors

Question 21

G-protein (bound to GTP) assists in transmitting the signal from receptor to enzyme

Answer 21

G-Protein Coupled Receptors

Question 22

What generates second messengers?

Answer 22

Membrane Receptors

Question 23

Small molecules that propagate a signal after it has been initiated by the binding of the signaling molecule to the receptor

Answer 23

Second Messenger

Question 24

Protein that functions to link transcriptional activators to the transcription complex

Answer 24

Coactivators

Question 25

Influence cell cycle, cell migration, cell metabolism, and cell proliferation and is a membrane receptor; alteration to function can lead to cancer

Answer 25

Receptor Tyrosine Kinase (RTK)

Question 26

What are RTKs composed of?

Answer 26

Single transmembrane protein, extracellular ligand-binding domain, intracellular kinase domain (catalytic site of receptor acts as a protein kinase)

Question 27

What happens when a ligand binds to an RTK?

Answer 27

Dimerization and autophosphorylation occur and cellular response follows

Question 28

What is a kinase cascade?

Answer 28

Series of protein kinases that phosphorylate each other in succession and amplified the signal because a few signal molecules can elicit a large cell response

Question 29

Thought to organize the components of a kinase cascade into a single protein complex and binds to individual kinase; must rely on substrates being near

Answer 29

Scaffold Proteins

Question 30

Small GTP binding protein that is the link between the RTK and MAP kinase cascade; mutated in many human tumors

Answer 30

Ras Proteins

Question 31

Protein bound to GTP

Answer 31

G-Protein

Question 32

Receptors bound to G proteins where a G protein is a switch turned on by the receptor and activates an effector protein

Answer 32

GPCR (G-Protein Coupled Receptor)

Question 33

When are G-proteins active?

Answer 33

When bound to GTP

Question 34

What composes most effector proteins?

Answer 34

Enzymes

Question 35

What does adenylyl cyclase produce?

Answer 35

cAMP

Question 36

What does cAMP do?

Answer 36

Binds and activates PKA which phosphorylates specific proteins

Question 37

What are examples of second messengers?

Answer 37

Calcium, inositol phosphates, phospholipase C