Cell Communication

Bio190 Chapter 8 Notes

Cells communicate with each other to coordinate activities and respond to environmental changes.
Communication can occur through a variety of methods including chemical signals, direct contact, and electrical signals.
Signals can be local (e.g., neurotransmitters) or systemic (e.g., hormones).

Cell communication often begins with the activation of receptors when they bind to specific signaling molecules (ligands).
Receptor activation initiates a cascade of intracellular events leading to a cellular response.
Ligand binding changes the conformation of the receptor, triggering its activity.

These receptors are located on the plasma membrane and interact with hydrophilic signaling molecules (e.g., peptides, proteins).
Types of cell surface receptors include:
- G Protein-Coupled Receptors (GPCRs): Activate intracellular signaling via G proteins.
- Receptor Tyrosine Kinases (RTKs): Function as enzymes that phosphorylate tyrosine residues, affecting cell growth and differentiation.
- Ion Channel Receptors: Open to allow ions to flow across membranes, altering the electrical state of the cell.

These receptors are located inside the cell, either in the cytoplasm or nucleus, and typically bind to hydrophobic signaling molecules (e.g., steroids, thyroid hormones).
Upon binding, the complex often translocates to the nucleus to regulate gene expression.
Intracellular receptors play crucial roles in the regulation of various metabolic processes and gene expression.