Cell Communication A.P. Biology Ch. 11

Goals & Objectives Describe in writing important communication pathways for a cell Describe in writing how each pathway works

Big Idea How do you get a message from outside the cell to inside? – Cell growth, cell division – Nerve cells Chemical messages are communicated by changing the shape of certain molecules – Change shape, trigger a response – “On/Off” switch

Local vs. Long Distance “Calling”

How Cell Communication Works Telephone Analogy Caller (your friend) Phone Tower/Switchboard Parent You Caller = Ligand (chemical signal) Phone Tower/Switchboard = Receptor protein in cell membrane (outside cell) Parent = Membrane bound protein (inside cell) You = Desired cell response

3 Phases in Cell Communication (ligand)

Using a Chemical Signal Ligand docks with receptor protein in membrane, causes shape change – Often caused by phosphorylation – Returns to original shape when ligand detaches Change in receptor protein causes a chain reaction of shape changes in other proteins – Signal Cascade – More phosphorylation (ATP  ADP + P) – Signal can be “amplified;” (think spam )

Example of a Signal Cascade **Notice that the addition of a phosphate causes shape change in protein kinase

3 Types of Cell Communication G protein – Single communication within membrane Tyrosine kinase – Many signals (amplification) Ion Channels – Allows flow of ions into/out of cells

G Protein Uses GTP (similar to ATP) Completely membrane bound Examples: – Hormones – Neurotransmitt ers – Epinephrine

Tyrosine Kinase Combining of two proteins, can phosphorylate 6 ATP at a time Massive phosphorylation causes multiple responses Cell growth/division

Ion Channel Ligand causes protein channel to open/close Ion flow causes cell response Nerve impulse/Nervous system

Apoptosis Programmed cell death (suicide) Triggered many different ways – Mitochondrial chemicals/molecules – Nuclear chemicals/DNA damage Necessary for development of an organism – Development of limbs – Get rid of cells that are harmful