CHAPTER 11
CELL COMMUNICATION
IS THIS THING ON?
3 types of cell signaling
http://www.sinauer.com/cooper5e/animation1503.html
1. Cell secretion
2. Nerve cells
3. Long distance
glandular
CELL COMMUNICATION IT’S A
CHEMICAL THING!
• THERE ARE 3 STAGES IN CELL
SIGNALING
• I. RECEPTION
• II. TRANSDUCTION
• III. CELL RESPONSE
I.
RECEPTION
• THE RECEIVING CELL HAS A RECEPTOR
MOLECULE THAT FITS TO THE SENDING CHEMICAL
MESSENGER CALLED A LIGAND
• THEY FIT LIKE A LOCK/KEY
• THIS CAUSES A CONFORMATIONAL CHANGE IN
THE RECEIVING MOLECULE TO SIGNAL A CHANGE
RECEPTORS 3 kinds
1. G-LINKED
• 1. G-LINKED, USUALLY HORMONAL, OR
NEUROTRANSMITTERS (NERVE) RELATED
TRANSMISSIONS
• A. ACTIVATION OF THE RECEPTOR ACTIVATES
GTP (GAUNOSINE TRIPHOSPHATE) A NUCLEOTIDE,
TO DISPLACE GDP ON A G PROTEIN
• B. THE G PROTEIN WILL BIND TO AN ENZYME AND
ALTERS ITS ACTIVITY
• C. THE G PROTEIN HYDROLYZES GTP TO BECOME
GDP AND IT WILL BE RECYCLED.
2. TYROSINE KINASE
RECEPTORS
• TYROSINE KINASE IS AN ENZYME. IT CAN
TRANSFER PO4 GROUPS FROM ATP TO
TYROSINE IN A PROTEIN
• BINDING OF THIS RECEPTORS CAUSES
POLYPEPTIDES (PROTEINS) TO JOIN
• THIS SIGNALS RELAY PROTEINS INSIDE
THE CELL WHICH CAN CAUSE A CELLULAR
CHANGE
• LET’S WATCH THE ANIMATION 11B
3. ION CHANNEL RECEPTORS
• ION CHANNELS ARE PORES IN THE CELL
MEMBRANE THAT ALLOW OR BLOCK IONS
• AN EXAMPLE IS NERVE CELL CONDUCTION
• 1. WHEN THE LIGAND BINDS TO THE RECEPTOR
MOLECULE IT OPENS A CHANNEL THROUGH THE
MEMBRANE
• 2. THIS ALLOWS IONS TO FLOW INTO THE CELL
• 3. THE CHANGE IN THE CONCENTRATION
GRADIENT CAUSES A CELLULAR CHANGE
Cell Signaling
Step II.TRANSDUCTION
• THE SIGNAL FROM THE RECEPTOR
MOLECULE CAUSES A
TRANSDUCTION PATHWAY TO OCCUR
• THIS CAN BRING ABOUT A CELLULAR
RESPONSE.
• IT CAN BE 1 TO SEVERAL STEPS
II.TRANSDUCTION
• A. TRANSDUCTION OFTEN INVOLVES
SMALLER, SECONDARY
MESSENGERS.
• 1. CYCLIC AMP IS ONE
• 2. CA+ IONS ARE ANOTHER
• B. IT ALSO INVOLVES
PHOSPHORYLATION (adding PO4) BY
ENZYMES CALLED KINASES
II.TRANSDUCTION CYCLIC AMP
• INITIATED BY G-PROTEIN & TYROSINE
KINASE RECEPTORS
EPINEPHERINE SIGNALINGHORMONE EXAMPLE
• LET’S SEE THESE SIGNALS IN ACTION
AND TAKE A QUIZ! Flight//Fight
response
II.TRANSDUCTION CA+ IONS
• LET’S WATCH 11C4
• http://www.bio.davidson.edu/courses/imm
unology/Flash/IP3.html
III. CELL RESPONSE
http://learn.genetics.utah.edu/content/begin/cells/signals/
• CAN COME IN MANY FORMS
• ENZYME ACTIVATION
• REARRANGEMENT OF
CYTOSKELETON
• GENE ACTIVATION
• OR HORMONE SECRETION