Lecture 15.6

• The three stages of cell signaling are reception, transduction, and response.
• Reception - signal molecule binds to receptor molecule.
• Transduction - receptor protein is changed to a signal molecule that can be detected by the cell.
• Response - how the cell responds to that signal molecule (i.e. activating an enzyme)
• Cells communicate using positive or negative feedback loops.
• Negative feedback mechanisms work to move the system towards homeostasis.
• Positive feedback mechanisms work to move the system further away from homeostasis.
• An example of a negative feedback mechanism is the regulation of blood sugar.
• An example of a positive feedback mechanism is childbirth.
• Unicellular organisms can respond to their environment through cell signaling.
• Quorum sensing is signaling pathways that respond to population density. (i.e. when bacteria glue together to form a biofilm)
• Cells aquire specialized properties during differentiation.
• Early embryonic cells have the potential to become almost any type of cell.
• Commitment is when a cell becomes dedicated to a cell specialization path.
• Once a cell is locked into a certain path is is now considered "determined"
• Plants do not get locked into fates like animals, they can change their developmental pathways