Dynamic cell communication
Dendritic cell- T cell control
DC- T cell recognition
Describe features of cell signaling systems.
Question: Why does high K+ in our blood signify death?
Cell Signaling, the most important new area in biology. For multicellular life,
signal systems are required. Cells are told how to behave, and to stay
Systems very similar and studied in yeast, C. elegans (worm), Drosophila (flies), animals
Systems can have multiple functions including vision, memory, cell division, muscle
Signaling molecules: protein, peptide, nucleotide, steroid, fatty acids, dissolved gases NO
and CO. Light and odor are also signals.
Cells have receptors for signaling molecules.
Binding signal leads to a cascade of intracellular "2nd messengers", and may include
regulators of gene expression.
Most involve protein kinases- add phosphate to a protein (518 protein kinase genes in
human cells, 1/3 proteins have Pi).
Cells are low in Na+ and high in K+. Cells are also low in Ca2+. Opening ion channels
allows rapid signaling.
Cell programmed for response, may include division.
A limited number of mechanisms are used for almost all signalling systems.
Describe the biological responses made to insulin, glucagon, epinephrine, and leptin.
Examples for regulating metabolism
emergency, fight or flight
liver; glycogen breakdown, glucose synthesis, slow glycolysis
muscle; glucose from liver, glycogen breakdown, increase glycolysis
adipose (fat); fatty acid release