Bio Lecture Ch 7.1

a sequence of molecular events and chemical reactions that lead to cell response to a signal.

signals that diffuse to and affect the cells that make them.

EX- cancer cells on normal cells. reproducing the cells uncontrollably.

signals that diffuse and affect nearby cells.

EX- a neurotransmitter made by one nerve and diffuses to the next and stimulates it

• a signal
• a receptor
• a response

an enzyme

function- transfers phosphate group from ATP to another molecule (an amino acid)

the second component of a signal transduction pathway

• the signal outside has trasduced to a protien
• the responder can act (ex-bind)
• the signal is amplified (conversion of one molecule to many of another)

• a receptor protein changes after being signaled
• a change in the receptor protien activates protein kinase, causing a transfer of a phosphate group (ATP to target protein)
• this transfer alters the responder protein function
• the signal is amplified
• a protein that bind to DNA is activated
• the expression on certain genes is turned on or off
• cell activity is altered