Joint 6 - Cell Communication & Proliferation

Question 1

how do receptor molecules have effects on many different cells?

Answer 1

different cells can have a receptor for the same receptor molecule/signal

Question 2

what do different combinations of receptors on a cell determine?

Answer 2

the cells behaviour
a cell can have multiple diff receptors
a diff combo of these signals changes function

Question 3

2 ways a extraceullular signal can bind?

Answer 3

• to extraceullular cell surface receptor [hydrophilic signal molecules]
• to intraceullar receptors or enzymes [hydrophobic signal molecules]

Question 4

steps a signalling pathway?

Answer 4

• signal mol bind to receptor [primary transduc]
• signal spreads in cell [relay]
• signal strength increase [amplify]
• protein receives moer than one signal input and produce the output [integrate]
• signal passed to other pathways [distribute]

Question 5

how is cell signalling regulated?

Answer 5

• by kinases and phosphatases
• alters the proteins conformation
• form docking site to allow other attachment

Question 6

role of GTPases in intracellular signalling?

Answer 6

• switch a signal on or off
• active if bound to GTP
• inactive if bound to GDP
• when signal entrs the GTPase has its GDP –> GTP
• carry signal forward

Question 7

types of extraceullar receptors inv in signalling?

Answer 7

• ion-ion channel receptors
• enzyme coupled recep
• g-protein coupled receptors

Question 8

structure of a g-protein?

Answer 8

• a-b-g subunits
• a unit bound to either GDP/GTP
• signal detected - a subunit changes shape

Question 9

how does a g-protein allow signal to pass through?

Answer 9

signal binds to receptor [confom change]
conformational change in G-proteins a-unit
exhnage of GDP to GTP 
a unit dissociates b/g stay together
both active and can downstream signals

Question 10

genenration of cyclic AMP?

Answer 10

Adenylcyclase + ATP

[cyclic AMP phosphodiesterase changes camp to amp to switch signal off]

Question 11

use glycogen breakdown by ADRENALINE pathway as a example to show interaction between camp and g-proteins?

Answer 11

• when the g protein activates it causes avtivation of camp

- camp activates PKA