(b) prevents dopamine from being converted to MAO-B 

(c) Inhibits COMT so less tyrosine would be made and more dopamine would be produced

(d) the agonist binds to the dopamine receptor and activates it, which then increase the sensitivity of dopamine

(e) so that the dopamine would only travel to the postsynaptic neurons and bind to the receptors 

2. (a) stem cells can differentiate to develop more dopamine secreting neurons

(b) gene alteration to change the base sequence that causes the loss of dopamine secreting neurons

3. 20ms

4.
5. 

6. hyperpolarization starts

 

1a) L-DOPA drug is used in formation of dopamine catalyzed by dopa decarboxylase. Therefore, dopamine will be created do the dopamine will increase. This will improve the symptoms of Parkinson’s disease.

 

b) Selegeline will slow down and prevents the break down of dopamine by inhibiting MAO-B from breaking down dopamine.

 

c)Tolcapone will slow down the break down of intermediate of dopamine by inhibiting COMT

 

d)Ropinirole will promote the function and activity of dopamine so this will support the movement.

 

e) Safinamide prevents the uptake so dopamine is not breakdown, and the levels od dopamine will increase which remains high in synapse. This will make the movement normal.

 

2a) Stem cells can differentiate and develop into normal neuron which can be replace the damaged neuron. (dopamine secreting neurons).

However, using embryotic stem cell is not ethical compare to adult stem cell.

 

b) Gene therapy can transfer the required gene and replace mutant gene. In this case, required gene is dopamine producing gene. Therefore, by transferring dopamine, cell can produce dopamine normally.

However, there is no guarantee that this will work, and it might cause a harmful DNA mutation and might transfer some toxic to the body.

 

Data-based questions: Analyzing an oscilloscope trace

 

1)    -73mv

2)    -30mv membrane potential starts to increase very steeply and need sodium ions to diffuse sodium channels to depolarize the membrane. 

3)    Time taken for depolarization-approximately 3ms

Time taken for repolarization-approximately 4ms

4)    More than 66ms as the graph haven’t reach to the resting potential yet.

5)    12action potentials per seconds. Because in one second, there is 1000ms. In one action potential. It occurs every 80ms before it goes back to the resting. Thus,1000/80=12 action potentials per seconds.

6)    Presence of potassium ions in the membrane. Some of the positive ions are still detected in the membrane which causes the membrane potential to rise after the repolarization. 

(b) selegiline is a selective monoamine oxidase B (MAO-B) inhibitor. MAO-B is an enzyme that breaks down dopamine in the brain. By inhibiting the action of the MAO-B enzyme, Eldepryl leads to an increase in the amount of dopamine.
(c) By inhibiting catechol-O-methyltransferase (COMT), tolcapone further decreases the degradation of levodopa in the periphery, which allows more levodopa to reach the brain and potentially allows for a decrease in the dosage of levodopa.
(d) Ropinirole has a high affinity for and stimulates the post-synaptic dopamine receptors D2 in the central and peripheral nervous systems. 
(e) Safinamide is a selective, reversible monoamine oxidase type B inhibitor. It also inhibits the release of glutamate, a substance that may have a role in motor fluctuations.
2)
(a) Stem cells have the potential for self-renewal through unlimited replication, as well as the capacity to differentiate into any cell type within the body. The ability to direct the fate of these cells to become a dopaminergic neuron potentially, therefore, offers an unlimited number of cells that could be used for neural grafting.
(b) Gene therapy is a category of treatments that involve introducing DNA into cells in an effort to alter which proteins are created and thereby improve symptoms or even cure disease.

1) -75mV
2) -30 mV because it is just before the steep incline of depolarisation. any
3)

2.