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Which of the following is not stored by the body
: fats , carbohydrates, amino acids ?
Amino Acids
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In terms of the first phase of amino acid catabolism , removal of the α-amino groups form what 2 structures ?
- 1) ammonia
-
- 2) the corresponding α-keto acid - the “carbon skeletons” of amino acids.
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In terms of the first phase of amino acid catabolism , a portion of the free ammonia is excreted where ?
Most of the free ammonia is used in the synthesis of what molecule ?
Urine
Urea
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In terms of the second phase what are the carbon skeletons of the α-keto acids are converted to ? They are metabolized into ?
Intermediates of energy producing, metabolic pathways
These compounds can be metabolized to CO2 and water, glucose,fatty acids, or ketone bodies by the central pathways of metabolism
-
How does nitrogen enter the body ?
Nitrogen enters the body in a variety of compounds in food, most important being amino acids contained in dietary protein
-
How is nitrogen removed from the body ? What is formed ?
- -urea
- -ammonia
- -other products
-
What do Pancreatic proteases cleave ?
What do Aminopeptidases breakdown?
Polypeptides
Produce even smaller peptides and free amino acids
-
The presence of what group of an Amino acid keeps the amino acids safely locked away from oxidative breakdown ?
a-amino group
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The first step in the catabolism of most AAs is the transfer of their α-amino group to α-ketoglutarate What is Transamination ?
What enzyme does this process ?
Is the transfer of amino groups from one carbon skeleton to another.
Aminotransferases (formerly transaminases)
-
What is deamination ?
Deamination of glutamate to α-ketoglutarate is done by ?
It is the removal of an amino group
Glutamate dehydrogenase
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What is the major disposal form of amino group derived from amino acids, and accounts for about 90% of the nitrogen components in
urine ?
Urea is produced by what organ ?, and then is
transported in the blood to the kidneys for excretion in urine
Urea
Liver
-
What does the urea cycle do ?
converts ammonia to urea, a less toxic molecule
-
Explain the Urea cycle process ?
1-Carbamoyl Phosphate - Carbomoyl phosphate synthetase
2-L-orithine
3-L-Citruline
4-L-Aspartate
5-L-Arginine > UREA is released
6-L-Ornithine
-
N-Acetylglutamate is an essential
activator of what enzyme ? This enzyme is the rate limiting step in the urea cycle.
carbomyl phosphate synthetase I
-
In patients with kidney failure, plasma urea levels is elevated, promoting a greater transfer of urea from blood to gut which contribute to ?
hyperammonemia
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Name the Essential amino acids and whether they are Glucogenic , Ketogenic , or Both ?
- Phenylalanine -GK
- Valine -G
- Tryptophan-Gk
- Threonine - G
- Isoleucine - GK
- Methionine - G
- Arginine - G - not essential
- Lysine -K
- Leucine - K
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The catabolism of AAs
involves the removal of α-amino
groups, followed by the breakdown of the resulting carbon skeletons , Which are important ?
These pathways
converge to form 7 intermediate products: oxaloacetate, pyruvate, α-ketoglutarate, fumarate, succinyl CoA, acetyl CoA and acetoacetate ,
oxaloacetate, pyruvate, α-ketoglutarate, fumarate, succinyl CoA, acetyl CoA and acetoacetate
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What can arginine and proline be synthesized from ?
glutamate
-
What is Phenylketonuria ?
Phenylalanine hydroxylase
results in an over-accumulation of phenylalanine, due to a deficiency of phenylalanine hydroxylase
-Strict diet controls (to reduce Phe) can prevent mental retardation and other brain damage.
-
What enzyme causes Albinism ?
Tyrosinase
results from a lack of tyrosinase and thus melanin is not produced. Albinos get skin cancer easily.
-
What are Porphyrins ? Where can they be found in the human body ?
are cyclic compounds that readily bind metal ions-usually Fe 2+ or Fe 3+
They can be found in heme of the blood
-
Where are the Major sites of heme biosynthesis ?
What percentage does bone marrow produce ?
Liver and Bone Marrow
liver and the erythrocyte-producing cells of the bone marrow (bone marrow accounts for about 85%)
-
The initial reaction and the last 3
steps in the formation of porphyrins occur in what structure of a cell ? whereas the
intermediate steps occur in the ?
Mitochondria
Cytosol
-
What does the lead poisoning effect in heme synthesis ?
- Aminolevulinic acid dehydratase
- (cystolic enzyme)
- Ferrochelatase
- (Mitochondrial enzyme)
-
What are the three molecules made before reaching heme ?
- Coproporphyrinogen III
- Protoporhyrinogen IX
- Protoporphyrin IX
- Heme
-
How is heme degraded ?
- Heme >heme oxygenase
- Biliverden >biliverdin reductase
- Bilirubin >
- Bile
-
What condition is seen when there is deposition of bilirubin ?
Juandice (icterus)
-
What amino acid is the precursor for dopamine, Epinephrine , Norepinephrine?
- Tyrosine >
- Dopamine >
- Epinephrine >
- Norepinephrine
-
Parkinson disease, a neurodegenerative movement disorder, is due to insufficient dopamine production , which can be caused by the lack of what amino acid ?
Tyrosine
-
Norepinephrine and epinephrine can ?
1)Regulate carbohydrate and lipid metabolism
2)Involved in the “fight or flight” response
-
What are epinephrine and norephinephrine broken down into ?
What is Dopamine degraded to ?
Vanillylmandelic acid (VMA)
Homovanillic acid
-
What amino acid is the precursor to Histamine ?
Histadine
-
What amino acid is the precursor to Serotonin ?
Tryptophan
-
What two amino acids are the precursors to creatine ?
Glycine and Arginine
-
How much creatine phosphate is in the body ?
It is proportionate to the muscle mass
-
What amino acid produces melanin ?
Tyrosine
-
Which has double rings , purines or pyrimidines ?
Name the Purines and Pyrimidines ?
purines
PurAG
PyrimiCUT
-
What is a Nucleoside ?
are composed of a nitrogenous base and a pentose monosaccharide
-
What is a nucleotide ?
The addition of one or more phosphate groups to a nucleoside produces a nucleotide
-
What is this molecule called :
Base
Nucleosides
Nucleotides
Deoxynucleside
DeoxyNucletide
Base
-
What is this molecule called :
Base
Nucleosides
Nucleotides
Deoxynucleside
Deoxynucletide
Nucleoside
-
What is this molecule called :
Base
Nucleosides
Nucleotides
Deoxynucleside
Deoxynucletide
Nucleotide
-
What is this molecule called :
Base
Nucleosides
Nucleotides
Deoxynucleside
Deoxynucletide
Deoxynucleoside
-
What is this molecule called :
Base
Nucleosides
Nucleotides
Deoxynucleside
Deoxynucletide
Deoxynucleotide
-
Where is the purine ring constructed ?
Liver
-
Explain Purine synthesis ?
- PRPP > glutamine ,glycine , aspartate , > IMP > AMP +GMP > Ribonucleotide reductase >
- dATP +dGTP > DNA
-
What chemical is administered to prevent to stop Gout ?
What enzyme is inhibited ?
allipurinol
Xanthine oxidase
-
What enzyme Inhibits the enzymes that convert IMP to AMP and GMP ?
6-Mercaptopurine (Purinethol)
-
Ribonucleotide reducatse can be inhibited by ?
Hydroxyurea
-
What does Thymidylate synthase catalyze the
conversion of ?
dUMP > dTMP
-
What does Dihydrofolate reductase reduces ?
Dihydrofolate to tetrahydrofolate
-
What are the major products of pyrimidine synthesis ?
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