Lect 4 - Cell Anatomy (Signals)

Question 1

Paracrine
- Target cell proximity
- Mode of transport

Answer 1

Target cells are neighbors
Diffusion

Question 2

Synaptic
- Target cell proximity
- Mode of transport

Answer 2

Target cells are close
Sometimes neurons are long meaning signal travels longer distance

Diffusion

Question 3

Endocrine
- Target cell proximity
- Mode of transport

Answer 3

Target Cells are long distance
Travels through blood

Question 4

Ligand

Answer 4

Molecule that binds to a receptor’s binding site

Question 5

If a messenger can cross a plamsa membrane what kind of trait must it posess

Answer 5

Non polar
Lipophilic

Question 6

Agonist

Answer 6

Binds to a receptor and activates it

Question 7

Antagonist

Answer 7

Binds to a receptor and does not activate it

Question 8

Intracellular Recepotrs

Answer 8

Lipophilic messengers can cross through the plasma membrane to bind to receptors in the cytosol or within the nucleus

Question 9

Receptor in cytosol

Answer 9

Lipophilic messenger diffuses across plasma membrane to bind receptor in cytosol

Forms a receptor ligand complex which can then enter the nucleus

Receptor-ligand complex functions as a transcription factor to change rate of DNA transcription

Question 10

Ionotropic Receptor

Answer 10

Ligand binds to receptor to open ion channel

Question 11

Enzyme Linked Receptor (Tyrosine Kinase)

Answer 11

Ligand binds to receptor
–> Conformational Change
–> Activates Tyrosine Kinase
–> Phosphorylates proteins
Leads to a response in cell

Question 12

Gs

Answer 12

Ligand binds to receptor releasing G-protein’s alpha subunit

–> Activates Adenylate Cyclase
–> Converts ATP into cAMP
–> Activates Phosphokinase A
–> PKA phosphorylates proteins leading to cell response

Question 13

Gi

Answer 13

Activation of G-protein releases alpha subunit which inhibits adenylate cyclase

Question 14

Gq

Answer 14

Ligand binds receptor to activate G protein releasing alpha subunit
–> Activates phospholipase C
–> Converts PIP2 into IP3 and DAG
IP3 moves to cytosol to cause release of calcium
DAG activates Protein Kinase C
–> PKC activates proteins

Question 15

Ca2+ Ion Channel

Answer 15

Ligand binds receptor which goes through a conformational change to allow Calcium into the cell

Ca2+ binds to calmodulin
–> Forms a Ca2+-Calmodulin complex
–> Activates a protein kinase
–> Response in cell