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Biochem > Exam 2 AA metabolism > Flashcards

Exam 2 AA metabolism Flashcards

1
Q
  1. What are ketogenic and glucogenic amino acids?
A

Ketogenic AA are metabolized to Acetyl CoA or acetoacetate.

Glucogenic AA are metabolized to pyruvate, 3-phosphoglycerate α-ketoglutarate, oxaloacetate, fumarate or Succinyl CoA

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2
Q
  1. What are essential and non-essential amino acids?
A

Essential AA cannot be synthesized by the body (Pvt Tim Hall acronym)

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3
Q

Name the mandatory keto acid and an amino acid in the transanimation reaction.

A

α-ketoglutarate is the mandatory keto acid.

Glutamate is the mandatory amino acid.

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4
Q

Describe the role of pyridoxal phosphate (vitamin B6) in the transanimation reaction.

A

Pyridoxal phosphate is the coenzyme involved in the transanimation reaction. In this reaction, the amino group is transferred from the amino acid to the coenzyme, which transports it to the α-keto acid, forming a new amino acid and regenerating the original coenzyme aldehyde.

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5
Q
  1. Describe the role of glutamine with reference to nitrogen catabolism.
A

Glutamine is the transporter of excess nitrogen from the tissues to the liver for the Urea cycle.

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6
Q

What are the substrates and products of glutaminase?

A

Glutaminase → Glutamate + Ammonia

(glutaminase)

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7
Q
  1. Name the two cellular compartments where the urea cycle operates.
A

Mitochondrial matrix and cytosol

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8
Q

. Name a drug that is used for treatment of a urea cycle enzyme deficiency.

A

carbamoylglutamate

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9
Q

In an exercising muscle, name the cycle that utilizes an amino acid and converts it into glucose.

A

Glucose-Alanine cycle

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10
Q

Name 2 neurotransmitters that are derived from tyrosine

A

dopamine

epinephrine

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11
Q

Name 3 types of reactions that are involved in producing a neurotransmitter from an amino acid precursor.

A

Decarboxylation
Hydroxylation
SAM-dependant methylation

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12
Q

Name 3 catacholamines

A

dopa, NE , Epi

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13
Q

Name the rate-limiting step in the biosynthesis of catacholamines.

A

Tyrosine + O2 + THB → DOPA + DHB

(Tyrosine hydroxylase)

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14
Q

Name the cofactor that is required for tyrosine hydroxylase.

A

Tetrahydrobiopterin

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15
Q

Catecholamine release is stimulated by the neurotransmitter ________?

A

Acetylcholine

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16
Q

Name two enzymes that are involved in catecholamine catabolism

A 
Catecholamine O-methyltransferase (COMT)
Monoamine oxidase (MAO)
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17
Q

Name few functions of catecholamines.

A

TO prepare the body for the “fight or flight” response:

Increase cardiac output, glycogen degradation, triglyceride hydrolysis and release of fatty acids from adipose tissue.

Decrease peripheral resistance to blood flow.

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18
Q

Discuss the connection between Parkinson’s disease and dopamine and the drug that is used for patients.

A

Parkinson’s disease is due to a lack of dopamine synthesis. It can be treated by L-DOPA, a precursor of dopamine that can cross the blood-brain barrier.

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19
Q
  1. Name 2 neurotransmitter compounds derived from tryptophan
A

Serotonin and melatonin

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20
Q

What are the substrates and products of carbamoyl phosphate synthase.

A

NH4+ + HCO3- + 2 ATP →
Carbamoyl phosphate + 2 ADP+Pi

(Carbamoyl phosphate synthase I / CPS-I)

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21
Q

Name the allosteric affector of carbamoyl phosphate synthase I

A

N-acetyl glutamate

22
Q

What is the hormone that is involved in circadian rhythms?

A

melatonin

23
Q

effect of prozac

A

inhibits reuptake of serotonin

24
Q

If you suffer from jet lag, what pathway would you target for drug therapy?

A

melatonin

25
Q

Name the enzyme that catalyzes the formation of histamine.

A

histidine carboxylase

26
Q

Name 3 functions of histamines

A

Mediate allergic and inflamatory reactions
Vasodiolation
Constriction of bronchioles
Stimulates excretion of HCl

27
Q

What are the substrates and products of glutamate decarboxylase?

A

Glutamate → GABA

glutamate decarboxylase

28
Q

. In general, decarboxylases require the coenzyme ________?

A

Pyridoxal Phosphate

29
Q

L-DOPA is used for _______ disease treatment?

A

Parkinson’s

30
Q

Name a synthetic compound that limits serotonin reuptake

A

prozac

31
Q

Describe pheochromocytoma.

A

Tumors of chromaffin tissue that produce large amounts of catecholines.

32
Q

Describe the clinical correlation between Huntington’s disease and GABA metabolism.

A

Low levels of GABA and GABAnergic neurons result in the uncontrolled movements of Huntington’s disease

33
Q

Melanins are synthesized in _______?

A

Melanocytes

34
Q

Tyrosinase deficiency causes _____?

A

albinism

35
Q

Under oxidative conditions, in order to maintain reducing environment inside the cell, which compound is invoked?

A

glutathione

36
Q

Name the methyl group donor compound that is used in the majority of methyl transfer reactions

A

S-adenosylmethionene (SAM)

37
Q

Name 2 functions of glutathione.

A 
Maintains protein sulfhydral groups in reduced form.
Detoxifies xenobiotics (peroxides and free radicals)
38
Q

Nitric oxide is derived from the amino acid _____?

A

Arginine

39
Q

Name the substrate and products of acetylcholinesterase

A

Acetylcholine + H2O → Acetate + Choline

(Acetylcholine esterase)

40
Q

40 Explain the action of DIPF on acetylcholinesterase:

A

DIPF is a component of nerve gas. It covalently modifies acetylcholinesterase and knocks the enzyme activity.

41
Q

Name some xenobiotics that inhibit acetylcholinesterase.

A

hysostigmine

Neostigmine

42
Q

Name the channel that is opened up by acetylcholine.

A

Na+ / K+ ion channels

43
Q

Name three excitatory and three inhibitory neurotransmitters:

A 
Excitatory:
acetylcholine
aspartate
dopamine
histamine
norepinephrine
epinephrine
glutamate
5-hydroxy tryptamine

Inhibitory:
glycine
taurine
4-aminobutyrate

44
Q

Name three stages of nerve transmission:

A

Resting
Excitation
Termination

45
Q

What is the function of phenobarbital?

A

Inhibits action potentials when bound to GABA receptors.

46
Q

Name the catabolic products of GABA.

A

Succinate semialdehyde

Succinate

47
Q

What is an ion-gated channel?

A

A channel that allows ions to pass through when a neurotransmitter binds to its receptor.Name two ion channels.

48
Q

name two ion channels

A

Cholingeric nicotinic receptors
GABA receptors
(More generally, Na+ and K+ ion channels)

49
Q

Diisopropylphosphoflouridate (DIPF) inhibits the enzyme___________.

A

acetylcholinesterase

50
Q

Name two inhibitors of the acetylcholine receptor.

A

Tubocurarine
α-bungarotoxin
Cobra toxin

51
Q

What is the action GABA?

A

GABA is an inhibitory neurotransmitter. Upon binding to its β subunits, it increases membrane permeability of postsynaptic membranes to chloride ion. This can lead to hyperpolarization and increased threshold of triggering an action potential.

Biochem (10 decks)

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