Exam 2 AA metabolism

Question 1

1. What are ketogenic and glucogenic amino acids?

Answer 1

Ketogenic AA are metabolized to Acetyl CoA or acetoacetate.

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

Question 2

2. What are essential and non-essential amino acids?

Answer 2

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

Question 3

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

Answer 3

α-ketoglutarate is the mandatory keto acid.

Glutamate is the mandatory amino acid.

Question 4

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

Answer 4

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.

Question 5

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

Answer 5

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

Question 6

What are the substrates and products of glutaminase?

Answer 6

Glutaminase → Glutamate + Ammonia

(glutaminase)

Question 7

8. Name the two cellular compartments where the urea cycle operates.

Answer 7

Mitochondrial matrix and cytosol

Question 8

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

Answer 8

carbamoylglutamate

Question 9

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

Answer 9

Glucose-Alanine cycle

Question 10

Name 2 neurotransmitters that are derived from tyrosine

Answer 10

dopamine

epinephrine

Question 11

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

Answer 11

Decarboxylation
Hydroxylation
SAM-dependant methylation

Question 12

Name 3 catacholamines

Answer 12

dopa, NE , Epi

Question 13

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

Answer 13

Tyrosine + O2 + THB → DOPA + DHB

(Tyrosine hydroxylase)

Question 14

Name the cofactor that is required for tyrosine hydroxylase.

Answer 14

Tetrahydrobiopterin

Question 15

Catecholamine release is stimulated by the neurotransmitter ________?

Answer 15

Acetylcholine

Question 16

Name two enzymes that are involved in catecholamine catabolism

Answer 16

Catecholamine O-methyltransferase (COMT)
Monoamine oxidase (MAO)

Question 17

Name few functions of catecholamines.

Answer 17

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.

Question 18

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

Answer 18

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.

Question 19

21. Name 2 neurotransmitter compounds derived from tryptophan

Answer 19

Serotonin and melatonin

Question 20

What are the substrates and products of carbamoyl phosphate synthase.

Answer 20

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

(Carbamoyl phosphate synthase I / CPS-I)

Question 21

Name the allosteric affector of carbamoyl phosphate synthase I

Answer 21

N-acetyl glutamate

Question 22

What is the hormone that is involved in circadian rhythms?

Answer 22

melatonin

Question 23

effect of prozac

Answer 23

inhibits reuptake of serotonin

Question 24

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

Answer 24

melatonin

Question 25

Name the enzyme that catalyzes the formation of histamine.

Answer 25

histidine carboxylase

Question 26

Name 3 functions of histamines

Answer 26

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

Question 27

What are the substrates and products of glutamate decarboxylase?

Answer 27

Glutamate → GABA | glutamate decarboxylase

Question 28

. In general, decarboxylases require the coenzyme ________?

Answer 28

Pyridoxal Phosphate

Question 29

L-DOPA is used for _______ disease treatment?

Answer 29

Parkinson’s

Question 30

Name a synthetic compound that limits serotonin reuptake

Answer 30

prozac

Question 31

Describe pheochromocytoma.

Answer 31

Tumors of chromaffin tissue that produce large amounts of catecholines.

Question 32

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

Answer 32

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

Question 33

Melanins are synthesized in _______?

Answer 33

Melanocytes

Question 34

Tyrosinase deficiency causes _____?

Answer 34

albinism

Question 35

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

Answer 35

glutathione

Question 36

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

Answer 36

S-adenosylmethionene (SAM)

Question 37

Name 2 functions of glutathione.

Answer 37

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

Question 38

Nitric oxide is derived from the amino acid _____?

Answer 38

Arginine

Question 39

Name the substrate and products of acetylcholinesterase

Answer 39

Acetylcholine + H2O → Acetate + Choline | (Acetylcholine esterase)

Question 40

40 Explain the action of DIPF on acetylcholinesterase:

Answer 40

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

Question 41

Name some xenobiotics that inhibit acetylcholinesterase.

Answer 41

hysostigmine | Neostigmine

Question 42

Name the channel that is opened up by acetylcholine.

Answer 42

Na+ / K+ ion channels

Question 43

Name three excitatory and three inhibitory neurotransmitters:

Answer 43

``` Excitatory: acetylcholine aspartate dopamine histamine norepinephrine epinephrine glutamate 5-hydroxy tryptamine ``` Inhibitory: glycine taurine 4-aminobutyrate

Question 44

Name three stages of nerve transmission:

Answer 44

Resting Excitation Termination

Question 45

What is the function of phenobarbital?

Answer 45

Inhibits action potentials when bound to GABA receptors.

Question 46

Name the catabolic products of GABA.

Answer 46

Succinate semialdehyde | Succinate

Question 47

What is an ion-gated channel?

Answer 47

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

Question 48

name two ion channels

Answer 48

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

Question 49

Diisopropylphosphoflouridate (DIPF) inhibits the enzyme___________.

Answer 49

acetylcholinesterase

Question 50

Name two inhibitors of the acetylcholine receptor.

Answer 50

Tubocurarine α-bungarotoxin Cobra toxin

Question 51

What is the action GABA?

Answer 51

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.