CH 9 Cell Communication

Question 1

What are the four steps of cell signalling?

Answer 1

Receptor activationSignal transductionResponseTermination

Question 2

Define receptor activation

Answer 2

The signal nods to a receptor which is then activated

Question 3

Define signal transduction

Answer 3

Signal is transmitted to the interior of the cell by a signal transduction pathway

Question 4

Define response

Answer 4

Cell responds for example by activating an enzyme or turning on transcription

Question 5

Define termination

Answer 5

The response is terminated so that new signals can be received

Question 6

What is the most important factor for communication in bacterial cells?

Answer 6

The number of cells (cell density)

Question 7

What are the four types of signalling and how far does the signal travel?

Answer 7

Endocrine - large distancesParacrine - up to 20 cellsAutocrine - cell is the signalling and responding cell (self)Juxtacrine - direct physical contact

Question 8

During endocrine signalling how is the signalling molecule transmitted?

Answer 8

Though the circulatory system

Question 9

Why do Paracrine signalling cells not signal themselves?

Answer 9

They do not contain receptors

Question 10

Does juxtacrine signalling cause a confirmational change ?

Answer 10

Yes

Question 11

Define ligand

Answer 11

Signalling molecule

Question 12

Define ligand binding site

Answer 12

Location on the receptor to which the ligand binds

Question 13

Polar molecules require which type of receptors to communicate?

Answer 13

Cell surface receptors

Question 14

Non Polar molecules require which type of receptors to communicate?

Answer 14

Intracellular receptors

Question 15

What are the three types of cell surface receptors?

Answer 15

G protein coupled receptorsReceptor kinasesLigand gated ion channels

Question 16

How are ions able to pass through ligand-gated ion channels?

Answer 16

Confirmational change, changes the shape of the ion channel to allow ones to pass through

Question 17

What are the three phases of G protein activation?

Answer 17

Alpha subunit is joined by three subunits and G protein is inactiveG protein gets bound by an activated receptor causing GDP to turn into GTP therefore activating the proteinActivated G proteins binds and activates target protein

Question 18

Explain the amplification of the adrenaline signal

Answer 18

Each activated receptor activates multiple G proteins which activates adenylyl Cyclase enzymesEach adenylyl Cyclase enzyme produce cAMP which activates protein kinase AEach protein kinase A activates multiple protein targets

Question 19

Explain termination of the G protein signal

Answer 19

Signal molecule detaches from the receptor after a certain amount of timeGTP is converted back to GDP in the G protein Enzymes in cytosol degrade cAMPPhosphotases removes phosphate groups from proteins causing them to become in active

Question 20

Explain receptor kinase activation and signalling

Answer 20

Signalling molecules bind to receptor causing a confirmational changeThis creates a dimer Each member of the receptor pair attaches phosphate groups to the other member The phosphate groups provide binding sites for intracellular signalling proteins

Question 21

Explain the MAP kinase pathway

Answer 21

Signalling molecule binds to inactive receptor causing it to be come active this activate the Ras proteinRas protein activates kinase 1 converting ATP to ADP which activates kinase 2 so fourth down to kinase 3 Causing change in gene expression

Question 22

What are the four essential elects for communication?

Answer 22

Signalling cellSignalling moleculeReceptor moleculeReceptor cell