Bio 12/4, 12/7, 12/9

Front 1

List the 7 kinds of cellular signals (hint, 3 major categories)

Back 1

1. diffusible paracrin signal
2. diffusible endocrin signal
3. diffusible neuro signal
4. contact dependent signals
5. extraorganismal mechanical
6. extraorganismal chemical
7. extraorganismal physical

Front 2

Diffusible paracrin signal

Back 2

a locally acting signal (like wound healing)

Front 3

Diffusible endocrin signal

Back 3

hormone signalling. present throughout the organism

Front 4

Diffusible neuro signal

Back 4

neurotransmitters are this type of signal

Front 5

contact dependent signals

Back 5

signals between cells that stick together & phagocytosis are examples. (cancer cells often ignore these signals)

Front 6

Extraorganismal mechanical

Back 6

touch, hearing, etc are examples

Front 7

Extraorganismal chemical

Back 7

taste, small are examples

Front 8

Extraorganismal physical

Back 8

light, heat, magnetodetection, etc are examples

Front 9

Two ways of getting information across the cell membrane

Back 9

1. Receptor-Ligand interactions
2. Signals pass directly through membrane

Front 10

Examples of receptor-ligand interactions:

Back 10

ligand gated ion channels, G-protein coupled receptors, enzyme linked receptors

Front 11

Properties of signals that can pass directly across membrane:

Back 11

small, non polar (like steroids & photons). need to pass from hydrophilic to hydrophobic to hydrophilic again.

Front 12

6 Key features of all signal transduction pathways:

Back 12

1. signals are <b>amplified</b>
2. signaling is <b>divergent</b> (one signal gets multiplied by multiple secondary messengers)
3. signaling is <b>convergent</b> (two different signals often have a secondary messenger in common)
4. signals are <b>highly regulated</b>
5. signals have <b>high temporal resolution</b> (can be rapidly turned on or off)
6. signals initiate a <b>cellular response</b>

Front 13

G Protein Coupled Receptors (GPCR)

Back 13

highly evolutionarily conserved
7 transmembrane domains
a diverse family of proteins (like olfactory receptors)

Front 14

What are the three families of G Proteins?

Back 14

G alpha s
G alpha i
G alpha p/q

Front 15

G alpha s

Back 15

activates Adenylyl Cyclase

Front 16

Adenylyl Cyclase

Back 16

converts ATP to cyclic AMP (cAMP), a very effective second messenger

Front 17

G alpha i

Back 17

activates Phosphodiesterase

Front 18

Phosphodiesterase

Back 18

converts cAMP to AMP (decreases levels of cAMP)

Front 19

G alpha p/q

Back 19

activates Phospholipase C

Front 20

Phospholipase C

Back 20

cleaves hydrphobic tail of off phosphatidyl inositol bisphosphate
(PIP2 -> DAG + IP3)
IP3 to IP3 receptor on ER
Ca++ from ER to cytoplasm

Front 21

What makes a good second messenger?

Back 21

1. rapidly changeable in concentration
2. expressed at low levels in cytoplasm
3. initiate a specific cellular response

Front 22

Cholera toxin

Back 22

elevates cAMP in gut epithelium by activating G alpha s. release of Na+ and H2O into lumen. 10% of people die from rapid + profound dehydration

Front 23

Pertussus toxin

Back 23

made by an air born bacteria. elevates cAMP. inhibits G alpha i in the lungs, leading to whooping cough.

Front 24

RP-cAMP

Back 24

dominant negative, inhibits camp by shutting down cAMP signal.

Front 25

SP-cAMP

Back 25

dominant active, elevates cAMP by activating cAMP signal

Front 26

Ways of shutting down G alpha s signalling

Back 26

1. endocytose the receptor
2. phosphatase (shuts down kinases)
3. phosphodiesterase (cAMP -> AMP)
4. activating G alpha i (inhibits G alpha s by blocking adenylyl cyclase)