Cell communication

Question 1

What are the difference between secrete cell signals

Answer 1

signal locally: nearby target cells

signal long distance: Endocrine system

Question 2

What are the 3 main steps within cell signaling “simplified”

Answer 2

1. Reception
2. Transduction
3. Response

Question 3

Describe the reception process

Answer 3

Allows or causes protein activation

receptor can change shape or chemical state

Question 4

Transduction

Answer 4

Each activated protein causes a series of changes via phosphorylation- (phosphorylation cascade)

Question 5

Response

Answer 5

activated protein causes one or more functions to occur in cell.

Question 6

Describe Receptors characteristics

Answer 6

Lock and key analogy

Only target receptor and target cell will interact with the ligand= transduction

Question 7

What are the two type of receptors

Answer 7

Intracellular receptors

Membrane bound/ cell surface receptor

Question 8

Describe Intracellular receptors

Answer 8

Hydrophobic
least common
lipid soluble
can cross the Pm easily
- testosterones/ estrogen

Question 9

Describe Membrane bound receptors

Answer 9

Hydrophobic
more common
Needs help crossing the PM
eg: G protein coupled receptor/ ligand gated ion

Question 10

Describe the structure of the G protein coupled receptor

Answer 10

g protein coupled receptor
g protein which is active (GDP or inactive GTP)
ENzyme

Question 11

Describe the G protein

Answer 11

Like a molecular switch

has attached inactive “GDP” or active GTP

Question 12

Describe the G-protein receptor being activitated

Answer 12

1. Inactive state GDP is bound to G-protein/ enzyme is inactive
2. Receptor binds to G- protein receptor/ Gprotein generates GDP and binds to receptor protein,
3. Gprotein with GDP binds to enzyme and causes activation
4. Returns to inactive state Gprotein hydrolyses GDP back to GTP and phosphate

Question 13

Ligand gated receptors description of activation

Answer 13

1. Gate is closed / ions remain on the outside of the channel/ ligand is not bound to the receptor
2. Ligand binds to the receptor/ gates open and ions flow through the protein= cellular response
3. Ligand detaches gate closed. ion remain outside of the channel

Question 14

Where are Ligand gated receptors found mostly

Answer 14

In the Nervous system

Question 15

What is signal Transduction

Answer 15

signals relayed to target molecule by a cascade of molecular interactions

Question 16

What is a protein kinases job in transduction

Answer 16

enzyme which transfers a phosphate group from ATP- to another protein= activation.

Question 17

Describe Transduction

Answer 17

Protein Kinase- enzymes that transfer a phosphate group from ATP to another protein= activation

Phosphatase: enzymes which dephospholate= protein inactive but recyclable

Question 18

Describe secondary messengers

Answer 18

Sometimes small molecules are included in cascade eg. cAMP and calcium ions

Question 19

Describe cAMP and transduction

Answer 19

Atp releases cAMP = cAMP acts as a secondary messenger= downstream cascade= phosphorylation cascade

Question 20

Calciums involvement as a secondary messenger

Answer 20

High conc outside of the cell
low conc within the cell
Calcium pump maintains Ca outside of the cell and within the cell.

Question 21

What is a example of cellular response

Answer 21

Gene expression

- Transduction leads to one or more cellular activities

Question 22

Describe Adrenalin stimulation of glycogen breakdown

Answer 22

Phospholation cascade occurs
Glycogen is converted
Ampliciation occurs from 1 molecule
= Multiple glycogen phosphorylase
= generate alot of glycogen quickly!