Cell Communication and Siganl Transaction

Importance of Cell Communication

• Cells must communicate to coordinate activities

• Cell signaling control

  • Growth and Division

  • Metabolism

  • Movement

  • Gene expression

What is cell Signaling

• The communication b/w cells using chemical signals

• Signal cell releases a ligand

• A target cell responds only if it has the correct receptor

3 Core Steps of Cell SIgnaling

• Reception

  • Ligand binds receptor

• Transduction

  • Signal converted inside the cell

• Response

  • Specific cellular effect

Recpetion

• When ligand binds a recepto

In class notes

• ATP IS ALWAYS PHOSPHATE DONAR

• PHOSPHORLIZATION IS FLIPPING THE SWITCH AND TURNING ON THE MOLECULE

Signaling DIstance (IMPORTANT FOR EXAM)

• Dircet contact

• Local signaling

• Long-distance signaling

Direct SIgnaling

• Requires physcal contact b/w cells

  • Gap juctions

  • Cell-cell recognition proteins

• Allows rapid coordination

Local Signaling

• Signals diffuse to nearby cells

  • Paracine: affects neighboring cells

  • Autocrine: cell signals itself (Cancer cells)

Long Distance (Endocrine) Signaling

• Hormones released into bloodstream

• Travel to distant target cells

• Only cells with receptors respond

Hydrophilic SIgnals

• Cannot cross membrane

• Use surface receptors

Hydrophobic Signals

• Cross membrane

• Use intracellular receptos

Surface Receptors

• Transmembrane proteins

• Ligand binding causes conformational change

• Initiates intracellular signaling cascade

Dont really need G-protein so much

• Key takaway that its a switch

• GTP is on

• GDP is off?

• Its a molecular loop