Cell signalling

Question 1

What is autocrine signalling

Answer 1

Cell signals itself

Question 2

What is endocrine signalling?

Answer 2

Signal to a far away cell

Question 3

What is paracrine signalling?

Answer 3

Cell signals to a close by cell

Question 4

What is intercellular signalling?

Answer 4

How one cell communicates with other cells within the organism
- direct physical contact

Question 5

What is intracellular signalling?

Answer 5

How signals from a receptor are transmitted within the cell
- causes cellular behavioral changes

Question 6

How do extracellular signal molecules ligate to cells?

Answer 6

Ligands (ESM) can bind (ligate) to cell-surface receptors or intracellular receptor

Question 7

True or false: most signal molecules are hydrophobic?

Answer 7

Most are hydrophilic and unable to cross plasma membrane

Question 8

What is the difference between cell-surface receptors and intracellular receptors?

Answer 8

Cell-surface receptor are hydrophilic therefore are on the surface
Intracellular receptors are hydrophobic therefore are in the cell

Question 9

What are the four forms of intracellular signalling?

Answer 9

Contact-dependent
Paracrine
Synaptic
Endocrine

Question 10

What form of intercellular signalling are nerve cells?

Answer 10

Synaptic

Question 11

What form of intercellular signalling are hormones?

Answer 11

Endocrine

Question 12

What form of intercellular signalling are budding yeast cells?

Answer 12

Paracrine

Question 13

What form of intercellular signalling are immune cells?

Answer 13

Contact-dependent

Question 14

What is the difference between synaptic and endocrine signalling?

Answer 14

Endocrine: transport through blood stream
Synaptic: transport through axons

Question 15

What are the effects of cell signalling?

Answer 15

Survive, grow+divide, differentiate, die

Question 16

What are the receptor classes?

Answer 16

Nuclear, ion channels, G-protein coupled, enzyme coupled

Question 17

Explain nuclear receptors

Answer 17

Binding of ligand to receptor causes a conformational change

Question 18

Give an example of nuclear receptors

Answer 18

Steroid hormones signalling

Question 19

Explain ion-channel linked receptors

Answer 19

Convert chemical signals to electrical signals
- gap junctions

Question 20

Explain G-protein link receptor

Answer 20

Signal transduction involves the production of 2nd messengers
- chemokine receptors

Question 21

Explain enzyme-linked receptor

Answer 21

Protein kinase receptors
- insulin receptors

Question 22

Explain ion channel coupled receptors

Answer 22

Reside within excitable tissue
- neuromuscular junction

Question 23

How is signalling information encoding affected by phosphate?

Answer 23

Through the addition/removal of phosphate group
- Phosphate added to protein
- GDP gets substituted by GTP

Question 24

What is the effect of phosphorylation?

Answer 24

Change of charge results in a conformational change (shape is different)

Question 25

Where is the G-protein in G-protein-coupled cell-surface receptors found?

Answer 25

The receptor sits in the cell membrane but the G-protein is inside the cell close to the membrane

Question 26

Explain G-protein-bound cell-surface receptor signalling

Answer 26

GDP is bound, receptor inactive Through a signal, GDP is replaced with GTP G proteins

Question 27

What is cyclic AMP and why is it important?

Answer 27

Synthesized by adenylyl cyclase from ATP Importance intra-cellular signalling (2nd messenger)

Question 28

What is an example of an important signalling complex

Answer 28

CD4 and T-cell receptor Changes in cell adhesion, gene expression and T cell regulation

Question 29

What is scaffold protein?

Answer 29

Where signalling molecules are kept together They get activated together

Question 30

What is mitogen-activated protein kinase (MAPK) pathway?

Answer 30

Activated by growth factors Cascade of kinases: Raf-Mek-Erk Leads to change in protein activity and changes in gene expression