Chapter 11 part 2

Question 1

Cells in a multicellular organism communicate with _____________, and this can be __________

Answer 1

signalling molecules, long or short distance

Question 2

What are cell junctions? How do they work?

Answer 2

Can connect cytoplasms of cells, which lets molecules that act as signals dissolved in cytosol pass between cells

Question 3

What is cell surface molecule communication? Where is it found?

Answer 3

(molecule on cell surface binds to receptor on another molecule)

This type of local signaling is especially important in embryonic development, the immune response, and in maintaining adult stem cell populations.

Question 4

paracrine signaling

Answer 4

Signalling cells release molecules which regulate target cells

Question 5

Synaptic signalling

Answer 5

Nerve cells release molecules called neyrotransmitters across a synapse to a target cell

Question 6

Endocrine signalling

Answer 6

Endocrine cells secrete hormones (usually through the bloodstream) and bind to a specific receptor on a specific type of cell

Question 7

What are hormones?

Answer 7

A type of secreted chemical that travels long distances through bodily fluids and acts on target cells to change their function

Question 8

What are the three steps of cell communication?

Answer 8

1. Signal reception (signalling molecule binds to receptor protein)
2. Signal transduction (Once molecule binds to receptor, receptor changes somehow and converts bond to cellular response. Usually takes several steps).
3. Cellular response

Question 9

How does the GPCR signaling pathway work?

Answer 9

1. GCPR is activated
2. G protein binds to GCPR
3. GTP displaces GDP (Activates g protein)
4. Activated G protein dissociates from receptor and binds to enzyme which alters its shape/function
5. Enzyme can start up next step, which causes cellular response
6. G protein hydrolyzes GTP, turns it back into GDP and phosphate (Inactivates GTP)
   6 G protein leaves enzyme, inactivates it. G protein can be reused, GTPase functino shuts down activity quickly when signaling molecule leaves.

Question 10

How does the receptor tyrosine kinase signaling pathway work?

Question 11

What do receptor tyrosine kinases do?

Answer 11

Regulate cell growth and division by receiving growth factors

Question 12

What does GCPR do?

Answer 12

Helps many neurotransmitters and hormones act

Question 13

Most water-soluble signaling molecules bind to specific sites on ______________ receptor proteins that transmit information from the _____________ to the ________________.

Answer 13

transmembrane, extracellular environment, inside of the cell

Question 14

A g protein coupled receptor is what kind of receptor?

Answer 14

Cell-surface transmembrane receptor

Question 15

What do GCPRs work with?

Answer 15

G protein

Question 16

What do G proteins do?

Answer 16

Bind GTP

Question 17

What are GCPRs used for?

Answer 17

Yeast mating factors, neurotransmitters, hormones, embryonic development, sensory reception

Question 18

What do G proteins function as? How do you know what state it’s in?

Answer 18

Molecular on/off switches, whether GDP/GTP is attached
GDP makes it inactive, receptor and GTP make it active (usually working with an enzyme)

Question 19

How does a GTP molecule bind to its receptor?

Answer 19

Once the receptor activates, it changes shape and lets GTP molecule bind to it.

Question 20

What do RTKs do?

Answer 20

Phosphorylate tyrosines on other RTK in a dimer

Question 21

What is the tyrosine kinase’s structure and function?(ADD FUNCTION)

Answer 21

The part of the receptor protein that extends into the cytoplasm

Question 22

Intracellular receptor proteins are found in either the ______or _______ of _____________

Answer 22

cytoplasm or nucleus, target cells

Question 23

The signal-activated receptor activates __________, which activates _____________, and so on, until _________ is activated.

Answer 23

another molecule, yet another molecule,the protein that produces the final cellular response

Question 24

How is protein activity regulated?

Answer 24

Phosphorylation and dephosphorylation of proteins

Question 25

What do protein kinases do?

Answer 25

Phosphorylate proteins from ATP

Question 26

What do phosphorylation cascades look like?

Answer 26

1.Signaling molecule binds to receptor, which activates a relay molecule.
2. That activates protein kinase 1, which activates protein kinase 2, etc (phosphorylation cascade).
3. Active protein kinase phosphorylates protein, which causes response.
4. Protein phosphatases dephosphorylate proteins, inactivating them

Question 27

Protein phosphatases do what?

Answer 27

Dephosphorylate proteins (inactivates them)