video 4 second messengers

Question 1

what is the first step in regulating PKA regulation gene transcription

Answer 1

-free catalytic enzymes from the

PKA can translocate from cytosol into the nucleus

Question 2

which 4 different receptors can activate phospholipase C signalling

Answer 2

PLC
DAG/IP3
Ca2+
PKC

Question 3

what does the ER membrane acts as a store for?

Answer 3

calcium

Question 4

what does IP3 do

Answer 4

diffuse through cells and bind to specific ion channels located in the membrane of endoplasmic reticulum

Question 5

what chemical does IP3 binding allow the release of

Answer 5

calcium

Question 6

what does IP3 increase

Answer 6

increases intracellular cytosolic calcium within the cell

Question 7

what is the function of calcium

Answer 7

-acts as a second messenger

Question 8

what activity does calcium regulate

Answer 8

the activity of some cellular proteins (some PKC proteins)

Question 9

if you add _____to a cell surface receptor, calcium stored in the ER is released within milliseconds

Answer 9

a ligand

Question 10

what protein does DAG activate

Answer 10

kinase C family members

Question 11

PKC family members are regulated by both…?

Answer 11

calcium and DAG

Question 12

the binding of both calcium and DAG creates a conformational change in an enzyme that does what

Answer 12

activates its catalytic activity

Question 13

what is MAPK an abbreviation of

Answer 13

Mitogen Activated Protein KInase

Question 14

List the pathway within MAPK signalling pathway

Answer 14

Ligand-receptor-first intracellular target-effector-downstream targets

Question 15

how is information amplified so that small inputs can yield large changes in output

Answer 15

on biological systems a specific threshold must be reached for an outcome to occur

Question 16

Name the 3 factors that affect whether a signalling pathway reaches its threshold

Answer 16

• production and breakdown of second messengers
• if a ligand remains bound to the receptor for too long, the receptor-ligand complex internalised by endocytosis and broken down inside the cell
• positive and negative feedback loops affect the strength of a signalling pathway

Question 17

what happens when you increase the ligand concentration in a cell (amplifying a signalling pathway)

Answer 17

• if you increase the concentration of a ligand within a population, every single cell in the population responds to the ligand–more and more receptors in each individual cell are being activated
• If a few cells in the population respond to a ligand and all of the receptors get activated, you fully activate the signalling pathway within that cell, you reach the biological outcome instantly-on/off scenario

Question 18

name the 4 amplification mechanisms involving enzymes

Answer 18

-turning a small input into a large output (e.g. binding of adrenaline to adrenoreceptors results in the synthesis of many cyclic AMP molecules
-2 camp can activate on PKA catalytic subunit
-Each pka catalytic subunit can phosphorylate multiple target molecules
-second level of amplification can involve several reactions in which the product of one reaction can activate an enzyme downstream
-

Question 19

what is the overall biological output of a pathway regulated by

Answer 19

feedback loops

Question 20

name the steps in positive feedback loops

Answer 20

• downstream target ‘B’ thats regulated by upstream molecule ‘A’
• molecules B has a positive feedback loop - activates A even further
• this results in a stonger signal

Question 21

name the steps in negative feedback loop

Answer 21

• downstream target B regulated by upstream molecule A
• molecule B has a negative feedback loop - inhibits A
• results in a weaker signal