4.1 Cell Communication

Cell Communication Types

1. Juxtacrine - Direct contact

2. Paracrine - Short distances

3. Endocrine - Long distances

Ligands

• biochem definition - molecule that forms a complex with another molecule to fulfill a biological function

• Molecule sending the signal

Receptor

molecule receiving the signal

Ligand-Receptor Complex

complex created when ligand and receptor combined

Juxtacrine

Signaling through direct contact between cells

• membrane bound ligand receptor complexes

• cytoplasmic connections

Only when the cell has signs of infections visible on its cell membrane

BPQ

At which stage in this virus’s life cycle would this cell be recognized as an infected cell by the immune system?

Cytoplasmic Connections

1. Gap Junctions

   • Animals

2. Plasmodesmata

   • Plants

Paracrine

Short distance communications

• neighboring cells

Development of body parts

regulated by paracrine signaling that leads to different expression of developmental genes

Synapses

Neurotrasmitters carries action potential from nerve cell to nerve cell

• through synapses, then attach to receptor on receiving cell

Endocrine

• Long distance signaling

Important Reminders

1. Receptors are selective but not perfect

   • Dopamine/Morphine

2. Not every cell will have a receptor for every ligand

3. Some cells will have different responses to the same ligand

   • Epinephrine

     • increases heart rate

     • dilates blood vessels

     • releases glucose from the liver