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45 Cards in this Set
- Front
- Back
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1. Why do we need amino acids?
Five reasons... |
1. Protein synthesis
2. Synthesis of important N compounds 3. Use of carbon skeletons for fuel 4. Use of carbon skeletons to make glucose and ketone bodies (important fate by mass) 5. Use of C requires excretion of amino nitrogen (urea/urine) |
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2. What are some important compounds synthesized from amino acids?
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1. Neurotransmitter
-GABA -Serotonin -Melatonin -Norepinephrine 2. Glutathione 3. Heme 4. Nucleotide bases -pyrimidines -purines 5. Creatine-P (NRG reservoir in muscles) |
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3. What are the 10 essential amino acids?
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1. Lysine (basic)
2. Histidine (basic) 3. Arginine (basic) 4. Leucine 5. Isoleucine 6. Valine 7. Threonine 8. Tryptophan 9. Phenylalanine 10. Methionine (S containing AA) |
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4. What charge do the basic amino acids have?
What are the branched AAs? What are the aromatic AAs? When is arginine required? |
Positive
Leucine, isoleucine, threonine, valine Tryptophan, phenylalanin During growth (not adulthood) **make alot in synthesis of urea |
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5. What will the body do if an essential AA is missing?
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Break down muscle protein to get it causing wasting
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6. What is the 2 C non-essential AA?
What are the 3 C non-essential AA? What are the 4 C non-essential AA? What are the 5 C non-essential AA? |
Glycine
Serine, cysteine (S), alanine Asparate, Asparagine Glutamate, Glutamine, Proline, Arginine (except in growing children) |
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7. What are the non-essential AA made from essential AA?
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Tyrosine (from phenylalanine)
Cysteine (from methionine) |
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8. What is meant by "complimentary proteins"?
Give an example |
Some plant protein sources are incomplete so remedy by consuming together
Legumes lack methionine Grains lack lysine **consume them together |
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9. What can low methionine cause?
What can low lysine cause? |
Retard growth in children
Hinder growth in children |
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10. What do most AA produce?
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Glucose (glucogenic)
-feed into TCA cycle to then form new glucose |
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11. What do the 3C AA form?
What do the 4C AA form? What do the 5C AA form? What do the branched chain AA form? |
Pyruvate
Oxaloacetate α-ketoglutarate Succingyl CoA |
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12. What are the only long term storage forms of energy in the body?
What can FAs only form? What can AA form? In a fast what happens then? |
Protein and Fat
Acetyl CoA (cannot form glucose) New glucose (and KB) 12 hr+ skeletal muscle degrades to make new glucose (lots of urea is also made) **Bulk of AA are gluconeogenic (use in long term fast like overnight) |
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13. What are the only 2 AA that can only form KB and not glucose?
What other AA are ketogenic as well as gluconeogenic? |
1. Lysine
2. Leucine Threonine, Isoleucine, Tryptophan, Phenylalanine, Tyrosine |
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14. What role does chewing play in protein digestion?
Does saliva contain proteases? What role does cooking food and HCl from the stomach play in protein digestion? |
Expose proteins
No Denature proteins so more susceptible to digestive processes -breaking down fibers and membranes to make proteins available |
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15. What does pepsin do in protein digestion?
What role does bicarbonate (released from the pancreas) play in protein digestion? What are the precursors to proteases found in the intestines? |
Cut proteins up into smaller pieces
Neutralize HCl from stomach in intestines Trypsinogen Chymotrypsinogen Preelastase Precarboxypeptidases A and B **Have to also digest these digestive enzymes which have a lot of protein in them |
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16. What is the precursor for pepsin and trypsin?
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Trypsinogen
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17. What is pepsin?
Where does it cleave? |
Stomach protease
Cleave after glutatate (Glu), asparatate (Asp), and some aromatic AA (tyrosine and phenylalanine) |
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18. From where is trypsin secreted?
Where is it found? Where does it cleave? |
Secreted from pancreas
Only in gut Cleave to carboxy side of either arginine (Arg) or lysine (Lys) |
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19. What is zymogen activation?
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Zymogen is the proenzyme or precursor form that is secreted by the pancreas
In order to form the active enzyme there must be activation of the zymogen |
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20. What is the zymogen of pepsin?
How is it activated? Where is pepsin active? |
Pepsinogen
Activates self with H+ Pepsin is only active in stomach |
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21. What is the zymogen of trypsin?
What activates it? What is special about trypsin? |
Trypsinogen (secreted by pancreas)
Enteropeptidase It activates most other gut proteases |
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22. Pepsin...
1. Location 2. Cleavage type 3. Cleaves after 4. Zymogen 5. Activation 6. Key Role |
1. Stomach
2. Endoprotease 3. Phe, Tyr, Glu, Asp 4. Pepsinogen 5. By acid, by pepsinogen 6. First protease |
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23. Trypsin...
1. Location 2. Cleavage type 3. Cleaves after 4. Zymogen 5. Activation 6. Key Role |
1. Intestine
2. Endoprotease 3. Lys, Arg 4. Trypsinogen 5. Enteropeptidase 6. Activates other zymogens |
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24. How are AA transported from the intestinal lumen to the portal vein or serosal side?
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1. Pull AA into cell w/ Na+
-sodium linked carriers -broad specificities -same transporters in gut, kidney 2. Facilitated transporter carriers cell out to serosal side |
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25. What are the 4 major nitrogenous urinary excretory products?
Why must we dispose of N? |
1. Urea (12-20 g urea N)
2. NH4+ (140-1,500 mg) 3. Creatinine (14-26 mg/kg females) (11-20 mg/kg males) 4. Uric Acid (250-750 mg) Must dispose of N to use carbon skeletons (α-keto acids) |
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26. Describe urea.
Four points |
1. Neutral molecule
2. Soluble 3. Non-toxic to mammals 4. Doesn't contain a lot of energy |
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27. Why is NH4+ not a good excretion molecule?
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1. Charged
-need to couple positive charge w/ negative charge 2. Soluble BUT toxic to mammals (neural toxicity) |
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28. What can creatine levels indicate and why?
What is creatine proportional to? |
How is at getting rid of small molecules (kidney function indicator b/c it's a specific breakdown molecule)
Muscle mass (less muscle, secrete less creatine) |
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29. What is uric acid a product of?
Describe uric acid? |
Purine breakdown
Insoluble -white crystalline mass |
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30. What happens in the aminotransferase reaction?
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Get N from any AA and trap it in glutamate
AA1 α-Keto acid1 α-Keto acid 2 AA2 **use PLP |
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31. How are AA1 and α-Keto acid 1 related?
What is the C skeleton of glutamate? From what vitamin is PLP derived from? |
α-keto acid 1 is C skeleton of AA1
α-ketoglutarate **capture N in form of glutamate B12 |
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32. What are some characteristics of aminotransferases?
Three things... |
1. Freely reversible: N goes both directions
2. An AT exists for nearly every AA 3. Most use Glutamate/α-ketoglutarate as one substrate produce pair |
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33. Describe the reaction in which glutamate dehydrogenase catalyzes?
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Glutamate <----> α-ketoglutarate
-freely reversible -NADP dependent (form NADPH if form α-ketoglutarate) Form NH4+ when form α-ketoglutarate |
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34. How can you form ammonia?
Five ways.... |
1. Glutamate dehydrogenase (GDH) reaction (glutamate -> α-ketoglutarate)
2. Asparagine -> Aspartate 3. Histidien -> Urocanate 4. Purine nucleotide cycle in muscles 5. AA to various products |
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35. How do you get N into urea?
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1. Transamination
-take N from AA and trap in glutamate 2. GDH -glutamate to NH4+ 3. NH4+ into urea cycle to form urea 4. Glutamate to aspartate which enters urea cycle |
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36. From where does the urea cycle ge the 2 N atoms it needs?
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1. One from ammonia (NH4+)
2. One from aspartate) |
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37. Where do the reactions of the urea cycle take place?
How is analogous to the TCA cycle? |
Mitochondria (liver cells)
Cytosol Cyclic Regenerate intermediates |
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38. What is the first reaction of the urea cycle in the mitochondria?
What is the enzyme involved? What else? What does the product do? |
Bicarbonate + NH4+ -> Carbamoyl P
Carboamoyl phosphate synthetase I (CPS I) 2 ATP Activated form of amino group that transfers it on to other groups |
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39. What is the second reaction of the urea cycle in the mitochondria?
What is the enzyme involved? What happens to the end product? |
Carbamoyl P + Ornithine -> Citrulline
Ornithine transcarbamoylase Transport citrulline out of mitochondria into cytosol |
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40. Where does the second N in the urea cycle come from?
What is an interesting intermediate in the urea cycle? What does the urea cycle regenerate that it uses? |
Aspartate
Arginine **this arginine doesn't escape from liver cells to supply rest of body w/ arginine Ornithine |
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41. What enzymes collaborate to send N to urea?
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Aminotransferases and GDH
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42. What regulates the Urea cycle?
(four) Which step is regulated? |
1. NAG
2. Glutamate 3. Ammonia 4. Arginine First step at CPS I |
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43. How does NAG affect CPS I?
How does arginine affect NAG? How does glutamate affect NAG? |
CPS I has allosteric activator (NAG) that is necessary
**NAG only activates CPS I when levels build up NAG synthesis is allosterically activated by arginine Glutamate is used to make NAG |
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44. How is urea production during fasting?
When is urea production the highest? |
Increases
B/c taking apart muscles/AA and the N is captured in urea Highest 12 hrs fasting |
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45. Why does urea production diminish after 5-6 weeks of fasting?
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Tissues that were dependent on glucose now use KB
Spare blood glucose so spare muscle degradation |
