Neurobiology of Disease 1 Flashcards
(169 cards)
Describe the 2 components in the structure of a dopamine molecule. (2)
- Catechol ring with 2 hydroxyl groups
- Amine group
Dopamine shares a common backbone with which 2 other neurotransmitters? (2)
What is the collective name given to these three neurotransmitters? (1)
- Noradrenaline
- Adrenaline
Catecholamines
Name the dietary amino acid from which dopamine is synthesised. (1)
Tyrosine
Dopamine is formed from tyrosine in two steps.
Name the intermediate formed from the first reaction with tyrosine. (1)
L-DOPA
Name the enzyme which converts tyrosine to L-DOPA. (1)
Tyrosine hydroxylase (TH)
Is tyrosine hydroxylase substrate specific or non substrate specific? (1)
Substrate specific
Name an essential cofactor for tyrosine hydroxylase to convert tyrosine to DOPA. (1)
Tetrahydrobiopterin (BH4)
Describe the molecular change which occurs when tyrosine is converted to L-DOPA. (1)
Addition of a hydroxyl group
Name the enzyme which converts DOPA to dopamine. (1)
DOPA decarboxylase
Why is DOPA decarboxylase described as a non substrate specific enzyme? (1)
It can convert any L-amino acid
What is the rate-limiting step in the synthesis of dopamine? (1)
Tyrosine hydroxylase conversion
Describe the molecular change which occurs when DOPA is converted to dopamine. (1)
Removal of a carboxyl group
Describe the relative levels of DOPA in the brain. (1)
Explain why this is the case. (1)
Level of DOPA in the brain is negligible.
Because conversion of DOPA to dopamine is very rapid.
Describe ‘substrate inhibition’ of tyrosine hydroxylase. (1)
Dopamine produced from TH action is able to inhibit TH.
(More TH action leads to increased dopamine, which inhibits TH leading to decreased dopamine)
Name two ways by which dopamine synthesis may be regulated in the brain. (2)
- Neuronal activity
- Autoreceptor feedback
Describe the general effect of neuronal activity on dopamine synthesis. (1)
Describe the mechanism of this. (2)
Neuronal activity increases dopamine synthesis
- Via calcium influx
- Calcium may activate tyrosine hydroxylase
Describe the general effect of autoreceptor feedback on dopamine synthesis. (1)
Describe the mechanism of this. (3)
Autoreceptor feedback inhibits dopamine synthesis and release.
- DA binds to presynaptic D2 autoreceptors
- Decreased cAMP signalling
- Decreased voltage-gated calcium channel activation
Name the molecular change which occurs when dopamine is converted to noradrenaline. (1)
Addition of a hydroxyl group
In addition to tyrosine hydroxylase and DOPA decarboxylase, noradrenergic neurones contain what other enzyme? (1)
dopamine b-hydroxylase
Name the enzyme which converts dopamine to noradrenaline. (1)
dopamine b-hydroxylase
In addition to tyrosine hydroxylase and DOPA decarboxylase, adrenergic neurones contain what other enzymes? (2)
dopamine b-hydroxylase
PNMT
Name the enzyme which converts noradrenaline to adrenaline. (1)
PNMT
Name the molecular change which occurs when noradrenaline is converted to adrenaline. (1)
Addition of a methyl group
Name the transporter protein which facilitates reuptake of dopamine from the synaptic cleft. (1)
dopamine transporter (DAT)