Q 01/05

Dopamine is made from its precursor L-DOPA by removing what?

A) A methyl group

B) A hydroxyl group

C) A carboxyl group

D) A sulfate group

Answer · why

C) A carboxyl group

The step is called decarboxylation and is done by the enzyme DOPA decarboxylase.

Q 02/05

Rather than pleasure itself, mainstream pharmacology holds that dopamine signals what?

A) Pain intensity

B) Motivational salience

C) Sleep pressure

D) Body temperature

Answer · why

B) Motivational salience

In other words it flags how desirable or aversive an outcome is and drives behaviour toward or away from it.

Q 03/05

To which chemical family, along with norepinephrine and epinephrine, does dopamine belong?

A) Endorphins

B) Cannabinoids

C) Indoleamines

D) Catecholamines

Answer · why

D) Catecholamines

It is the simplest possible catecholamine: a benzene ring with two hydroxyl groups and an amine on an ethyl chain.

Q 04/05

The primary synthesis pathway for dopamine starts with which essential amino acid?

A) Methionine

B) Phenylalanine

C) Isoleucine

D) Tryptophan

Answer · why

B) Phenylalanine

Phenylalanine becomes tyrosine, tyrosine becomes L-DOPA and L-DOPA becomes dopamine.

Q 05/05

Which enzyme carries out the rate-limiting step of dopamine synthesis, turning an amino acid into L-DOPA?

A) Dopamine beta-hydroxylase

B) DOPA decarboxylase

C) Tyrosine hydroxylase

D) Monoamine oxidase

Answer · why

C) Tyrosine hydroxylase

It needs tetrahydrobiopterin, oxygen and iron as cofactors.