Lecture 5 : Nitrogen Metabolism

Card Set Information

Author:
glparker86
ID:
282090
Filename:
Lecture 5 : Nitrogen Metabolism
Updated:
2014-09-08 00:37:55
Tags:
Biochem
Folders:

Description:
Bio
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user glparker86 on FreezingBlue Flashcards. What would you like to do?


  1. Which of the following is not stored by the body
    : fats , carbohydrates, amino acids ?
    Amino Acids
  2. 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.
  3. 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
  4. 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
  5. 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
  6. How is nitrogen removed from the body ? What is formed ?
    • -urea
    • -ammonia
    • -other products
  7. What do Pancreatic proteases cleave ? 

    What do Aminopeptidases breakdown?
    Polypeptides

    Produce even smaller peptides and free amino acids
  8. The presence of what group of an Amino acid keeps the amino acids safely locked away from oxidative breakdown ?
    a-amino group
  9. 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)

  10. What is deamination ?

    Deamination of glutamate to α-ketoglutarate is done by ?
    It is the removal of an amino group

    Glutamate dehydrogenase

  11. 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
  12. What does the urea cycle do ?
    converts ammonia to urea, a less toxic molecule
  13. 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
  14. N-Acetylglutamate is an essential
    activator of what enzyme ? This enzyme is   the rate limiting step in the urea cycle.
    carbomyl phosphate synthetase I
  15. In patients with kidney failure, plasma urea levels is elevated, promoting a greater transfer of urea from blood to gut which contribute to ?
    hyperammonemia
  16. 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
  17. 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
  18. What can arginine and proline be synthesized from ?
    glutamate
  19. 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.
  20. What enzyme causes Albinism ?
    Tyrosinase

    results from a lack of tyrosinase and thus melanin is not produced.  Albinos get skin cancer easily.
  21. What are Porphyrins ? Where can they be found in the human body ?
    are cyclic compounds that readily bind metal ions-usually Fe2+ or Fe3+

    They can be found in heme of the blood

  22. 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%)
  23. 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
  24. What does the lead poisoning effect in heme synthesis ?
    • Aminolevulinic acid dehydratase
    • (cystolic enzyme)

    • Ferrochelatase
    • (Mitochondrial enzyme)
  25. What are the three molecules made before reaching heme ?
    • Coproporphyrinogen III
    • Protoporhyrinogen IX
    • Protoporphyrin IX
    • Heme

  26. How is heme degraded ?
    • Heme >heme oxygenase
    • Biliverden >biliverdin reductase
    • Bilirubin >
    • Bile
  27. What condition is seen when there is deposition of bilirubin ?
    Juandice (icterus)
  28. What amino acid is the precursor for  dopamine, Epinephrine , Norepinephrine?
    • Tyrosine >
    • Dopamine >
    • Epinephrine >
    • Norepinephrine
  29. Parkinson disease, a neurodegenerative movement disorder, is due to insufficient dopamine production , which can be caused by the lack of what amino acid ?
    Tyrosine
  30. Norepinephrine and epinephrine can ?
    1)Regulate carbohydrate and lipid metabolism

    2)Involved in the “fight or flight” response
  31. What are epinephrine and norephinephrine broken down into ?

    What is Dopamine degraded to ?
    Vanillylmandelic acid (VMA)

    Homovanillic acid
  32. What amino acid is the precursor to Histamine ?
    Histadine
  33. What amino acid is the precursor to Serotonin ?
    Tryptophan
  34. What two amino acids are the precursors to creatine ?
    Glycine and Arginine
  35. How much creatine phosphate is in the body ?
    It is proportionate to the muscle mass
  36. What amino acid produces melanin ?
    Tyrosine
  37. Which has double rings , purines or pyrimidines ?
    Name the Purines and Pyrimidines ?
    purines 

    PurAG 

    PyrimiCUT
  38. What is a Nucleoside ?
    are composed of a nitrogenous base and a pentose monosaccharide

  39. What is a nucleotide ?
    The addition of one or more phosphate groups to a nucleoside produces a nucleotide

  40. What is this molecule called :
    Base
    Nucleosides
    Nucleotides
    Deoxynucleside 
    DeoxyNucletide 

    Base
  41. What is this molecule called :  
    Base
    Nucleosides
    Nucleotides
    Deoxynucleside 
    Deoxynucletide
    Nucleoside
  42. What is this molecule called :  
    Base
    Nucleosides
    Nucleotides
    Deoxynucleside 
    Deoxynucletide
    Nucleotide
  43. What is this molecule called :
    Base
    Nucleosides
    Nucleotides
    Deoxynucleside 
    Deoxynucletide
    Deoxynucleoside
  44. What is this molecule called :
    Base
    Nucleosides
    Nucleotides
    Deoxynucleside 
    Deoxynucletide
    Deoxynucleotide
  45. Where is the purine ring constructed ?
    Liver
  46. Explain Purine synthesis ?
    • PRPP > glutamine ,glycine , aspartate , > IMP > AMP +GMP  > Ribonucleotide reductase >
    • dATP +dGTP > DNA



  47. What chemical is administered to prevent to stop Gout ?

    What enzyme is inhibited ?
    allipurinol 

    Xanthine oxidase
  48. What enzyme Inhibits the enzymes that convert IMP to AMP and GMP ?
    6-Mercaptopurine (Purinethol)
  49. Ribonucleotide reducatse can be inhibited by ?
    Hydroxyurea
  50. What does Thymidylate synthase catalyze the
    conversion of ?
    dUMP > dTMP
  51. What does Dihydrofolate reductase reduces ?
    Dihydrofolate to tetrahydrofolate
  52. What are the major products of pyrimidine synthesis ?
    • β-amino acids
    • CO2
    • NH3

What would you like to do?

Home > Flashcards > Print Preview