Chapter 11 Cell Communication

Front 1

Signal Transduction Pathway

Back 1

a series of steps by which a signal on a cell's surface is converted into a specific cellular response

Front 2

Multicellular Organism communicate by ...

Back 2

chemical messengers

Front 3

Cell Junctions

Back 3

-in animal and plant cells
-directly connect the cytoplasm of adjacent cells

Front 4

Local Signaling

Back 4

communicate by direct contact, or cell-cell recognition

Front 5

Local Regulator

Back 5

messenger molecules that travel only short distances

Front 6

Long-Distance Signaling

Back 6

plants and animals use chemicals called hormones

Front 7

Three Stages of Cell Signaling

Back 7

-Reception
-Transduction
-Response

Front 8

Reception

Back 8

a signal molecule binds to a receptor protein, causing it to change shape

Front 9

Three Main types of Membrane Receptors

Back 9

-G-protein coupled receptors
-Receptor tyrosine kinases
-Ion channel receptors

Front 10

Signaling through G-protein coupled receptors

Back 10

1. External signal
2. Activated receptor
3. GDP or GTP
4. Enzyme activated
5. CELLULAR RESPONSE

Front 11

Signaling molecules that use G-protein coupled receptors

Back 11

-yeast mating factors
-epinephrine
-rhodopsin

Front 12

Receptor Tyrosine Kinases

Back 12

membrane receptors that attach phosphates to tyrosines

Front 13

Tyrosine kinase receptors

Back 13

-epidermal growth factor receptor (EGFR)
-Platelet derived growth factor receptor (PDGFR)
-vascular endothelial growth factor receptor (VEGFR)

Front 14

Signaling through tyrosine kinase receptors

Back 14

1. External Signal (ligand binding)
2. Dimerization of receptor
3. Activation of receptor by phosphorylation
4. Activation of relay proteins
5. CELLULAR RESPONSE

Front 15

Ligand Gated Ion Channel

Back 15

receptor acts as a gate when the receptor changes shape

Front 16

Intracellular Receptors

Back 16

-found in the cytosol or nucleus of target cells
-small or hydrophobic chemical messengers (steroid and thyroid hormones) can readily cross the membrane and activate receptors

Front 17

Transduction

Back 17

cascades of molecular interactions relay signals from receptors to target molecules in the cell

Front 18

Signal Transduction Pathways

Back 18

-molecules relay a signal from receptor to response
-the receptor activates another protein, until the protein producing response is activated
-at each step, the signal is transduced into a different form, usually a shape change in a protein

Front 19

Phosphorylation

Back 19

protein kinases transfer phosphates from ATP to protein

Front 20

Dephosphorylation

Back 20

protein phosphates remove the phosphates from proteins

Front 21

Second Messengers

Back 21

small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion
-participate in pathways initiated by G protein-coupled receptors and receptor tyrosine kinases
- ex. cyclic AMP and calcium ions

Front 22

cAMP

Back 22

one of the most widely used second messengers.
-adenylyl cyclase, an enzyme in the plasma membrane, converts ATP to cAMP in response to an extracellular signal

Front 23

Calcium Ions and Inositol Triphosphate

Back 23

-cells can regulate calcium concentration
-a signal relayed by a signal transduction pathway may trigger an increase in calcium in the cytosol
-pathways leading to the release of calcium involve IP3 and DAG as additional second messengers

Front 24

Output Response

Back 24

cell's response to an extracellular signal

Front 25

Termination of a Signal

Back 25

when signal molecules leave the receptor, the receptor reverts to its inactive state