Cell Communication

Wow, I did a LOT of talking today! 

Our cell communication lesson went like this:
1. Analogy of BHS as a community of populations that each perform specific roles, which increases efficiency.  However, clear communication is vital to the smooth functioning of the community.
2.  Multicellular organisms are like communities as well with different organs performing specific functions and communicating with other organs.
3.  Cell communication can occur at three different distances
     - Direct cell-to-cell contact: cells physically connect.  Examples are antigen-presenting cells of the immune system, plasmodesmata in plants and gap junctions in animals.
     - Local communication: cells release signals that act on target cells in the immediate vicinity.  Examples are interleukin released by some immune cells, neurons using neurotransmitters, mating in yeast, quorum sensing in bacteria.
     - Long-distance communication: signal molecules are released by a gland and travel through the bloodstream to a target.  Example is hormones.
4.  The three stages of signal transduction are:

1. Reception - a target cell must have a specific protein receptor for the signal molecule.  This protein may be in the cell membrane to receive a protein or amine-based signal or in the cytoplasm to receive a hydrophobic signal.
2. Signal Transduction - links signal reception with cellular response.  Signaling cascades relay signals from receptors to cell targets, often amplifying the incoming signals, with the result of appropriate responses by the cell.  Second messengers are often essential to the function of the cascade.
3. Response - may be a change in gene expression, protein activity, or cell death.

Some important things to remember:

• because each cell uses different molecules in its signal transduction pathway different cells can have very different responses to the same signal.
• changes to the signaling transduction pathway can lead to disease.  Examples are diabetes, heart disease, multiple sclerosis, Parkinson's, alzheimers, AIDS, lupus, cancer, cholera

There is no homework tonight, but remember that test corrections are due tomorrow at 3:05!