BIO 390
Why is it so important to keep Ca2+ levels low inside the cell, and how is this
accomplished? - CORRECT ANSWER-Ca+ is the most commonly used 2nd
messenger. The intracellular conc. Is very low and the extracellular conc. Is
several times larger. A rise in Ca leads to receptor activation -> kinases -> and
the phos. Of targets.
How are levels of Ca2+ increased inside cells? - CORRECT ANSWER-1. Voltage
gated Ca channels on pm.
2. Ligand gated channels like NMDA Rs, on pm.
3. IP3 & RYR receptors on ER, Ca release from ER.
How are levels of Ca2+ decreased inside cells? - CORRECT ANSWER-1. Ca
ATPase pump, 1 degree active transport on pm & ER.
2. Ion exchangers, antiport, 2nd degree active transport, Na in Ca out.
3. Buffer proteins, Ca binds to protein to inhibit fcn ex: calbinin.
Protein kinases and phosphatases are major targets of second messenger
systems. Why is it so important to regulate protein phosphorylation? - CORRECT
ANSWER-Phosphorylation rapidly changes protein fcn/structure. Kinases add a
Pi group from ATP & activate a protein. Phosphatases remove the Pi &
deactivate it.
We specifically talked about channels and
receptors - how are their actions altered by phosphorylation? - CORRECT
ANSWER-Can alter: the affinity (more of less likely to bind a nt) of a R, sensitivity
to voltage, the # of chnls/Rs in pm (density), the kinetics for opening, closing, &
inactivation (how fast a chnl opens or closes), and stabilization or destruction.
What other downstream effectors
can be altered by protein phosphorylation? - CORRECT ANSWER-Effector
enzymes that make 2nd messengers.
Describe the step in the cAMP system pathway. - CORRECT ANSWER-A nt
binds to a R, the G alpha s protein activates AC to act on ATP, removes Pi =
cAMP, 4 cAMP binds to PKA's regulatory subunits. PKA becomes activated and
, the catalytic subunits go on to phosphorylate ser/thr targets, resulting in change
in fcn/structure.
Describe the step in PIP2 system pathway. - CORRECT ANSWER-A nt binds to
a R, the G protein q subunit activates phospholipase C to act on PIP2 so it splits
into IP3 and DAG, both act as 2nd messengers independently. DAG + Ca
activates PKC to phosphorylate targets, IP3 binds to Rs on the ER to facilitate
release of Ca.
How are protein tyrosine kinases similar and different from the other types of
protein kinases that we discussed? Functionally and structurally? - CORRECT
ANSWER-Tyrosine kinases are enzyme linked, once a ligand binds to an R 2
subunits come together (dimerization) and autophosphorylation occurs. The R
itself has enzymatic activity. R tyr kinase -> ras -> MAPK -> phosphorylate CREB
w/in the nucleus along with other protein kinases to alter RNA transcription.
What are and describe in detail the three types of SHORT-TERM synaptic
plasticity that result in an increase in synaptic strength? How do their time
courses differ? Are these changes pre-
synaptic or postsynaptic? - CORRECT ANSWER-Paired pulse facilitation -
msecs. When 2 APs are closely spaced.
Augmentation - secs. Occurs after repeated stim, induce a longer response.
PTP - Post tetanic potentiation, mins. High freq stim, produces a longer response
than augmentation
Ca build up in presyn terminal. Enhance the ability of Ca to trigger fusion of
vesicles to pm to release contents.
What is the synaptic basis (cellular mechanisms) for short-term sensitization in
Aplysia? - CORRECT ANSWER-The modulatory neuron, stimulated from its tail,
releases 5HT onto the sensory neuron of the siphon. The 5HT R is activated, G
alpha s protein stim AC -> cAMP -> PKA's catalytic subunits phos targets. K
channels are blocked to lengthen AP duration, more Ca channels open to allow
Ca in -> more vesicles release their contents (glutamate) to Rs on motor neuron
-> Ach onto gill.
What additional changes underlie long-term sensitization? - CORRECT
ANSWER-During long term sensitization, repeated stim has PKA activate CREB
Why is it so important to keep Ca2+ levels low inside the cell, and how is this
accomplished? - CORRECT ANSWER-Ca+ is the most commonly used 2nd
messenger. The intracellular conc. Is very low and the extracellular conc. Is
several times larger. A rise in Ca leads to receptor activation -> kinases -> and
the phos. Of targets.
How are levels of Ca2+ increased inside cells? - CORRECT ANSWER-1. Voltage
gated Ca channels on pm.
2. Ligand gated channels like NMDA Rs, on pm.
3. IP3 & RYR receptors on ER, Ca release from ER.
How are levels of Ca2+ decreased inside cells? - CORRECT ANSWER-1. Ca
ATPase pump, 1 degree active transport on pm & ER.
2. Ion exchangers, antiport, 2nd degree active transport, Na in Ca out.
3. Buffer proteins, Ca binds to protein to inhibit fcn ex: calbinin.
Protein kinases and phosphatases are major targets of second messenger
systems. Why is it so important to regulate protein phosphorylation? - CORRECT
ANSWER-Phosphorylation rapidly changes protein fcn/structure. Kinases add a
Pi group from ATP & activate a protein. Phosphatases remove the Pi &
deactivate it.
We specifically talked about channels and
receptors - how are their actions altered by phosphorylation? - CORRECT
ANSWER-Can alter: the affinity (more of less likely to bind a nt) of a R, sensitivity
to voltage, the # of chnls/Rs in pm (density), the kinetics for opening, closing, &
inactivation (how fast a chnl opens or closes), and stabilization or destruction.
What other downstream effectors
can be altered by protein phosphorylation? - CORRECT ANSWER-Effector
enzymes that make 2nd messengers.
Describe the step in the cAMP system pathway. - CORRECT ANSWER-A nt
binds to a R, the G alpha s protein activates AC to act on ATP, removes Pi =
cAMP, 4 cAMP binds to PKA's regulatory subunits. PKA becomes activated and
, the catalytic subunits go on to phosphorylate ser/thr targets, resulting in change
in fcn/structure.
Describe the step in PIP2 system pathway. - CORRECT ANSWER-A nt binds to
a R, the G protein q subunit activates phospholipase C to act on PIP2 so it splits
into IP3 and DAG, both act as 2nd messengers independently. DAG + Ca
activates PKC to phosphorylate targets, IP3 binds to Rs on the ER to facilitate
release of Ca.
How are protein tyrosine kinases similar and different from the other types of
protein kinases that we discussed? Functionally and structurally? - CORRECT
ANSWER-Tyrosine kinases are enzyme linked, once a ligand binds to an R 2
subunits come together (dimerization) and autophosphorylation occurs. The R
itself has enzymatic activity. R tyr kinase -> ras -> MAPK -> phosphorylate CREB
w/in the nucleus along with other protein kinases to alter RNA transcription.
What are and describe in detail the three types of SHORT-TERM synaptic
plasticity that result in an increase in synaptic strength? How do their time
courses differ? Are these changes pre-
synaptic or postsynaptic? - CORRECT ANSWER-Paired pulse facilitation -
msecs. When 2 APs are closely spaced.
Augmentation - secs. Occurs after repeated stim, induce a longer response.
PTP - Post tetanic potentiation, mins. High freq stim, produces a longer response
than augmentation
Ca build up in presyn terminal. Enhance the ability of Ca to trigger fusion of
vesicles to pm to release contents.
What is the synaptic basis (cellular mechanisms) for short-term sensitization in
Aplysia? - CORRECT ANSWER-The modulatory neuron, stimulated from its tail,
releases 5HT onto the sensory neuron of the siphon. The 5HT R is activated, G
alpha s protein stim AC -> cAMP -> PKA's catalytic subunits phos targets. K
channels are blocked to lengthen AP duration, more Ca channels open to allow
Ca in -> more vesicles release their contents (glutamate) to Rs on motor neuron
-> Ach onto gill.
What additional changes underlie long-term sensitization? - CORRECT
ANSWER-During long term sensitization, repeated stim has PKA activate CREB
