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5: MBOD Get Pumped haha > Urea Cycle Khan > Flashcards

Urea Cycle Khan Flashcards

1
Q
  1. What is the compound that is excreted containing nitrogen?
A
  1. Urea
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2
Q
  1. What funnels amino groups into glutamate?
A
  1. Transamination reactions
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3
Q
  1. Transamination moves an amino group from an AA to what?
A
  1. Alpha keto acid
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4
Q
  1. What do all transaminases use to transfer amino groups?
A
  1. Pyridoxyl 5’ phosphate (PLP)
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5
Q
  1. What does Ala + alphaketoglutarate produce via ALT ?
A
  1. Pyruvate and glutamate
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6
Q
  1. What does glutamate and oxaloacetate produce via AST?
A
  1. Alphaketoglutarate and aspartate
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7
Q
  1. If there is an abnormal increase in the substrates for these reactions (AST and ALT) what organ
    is in failure?
A
  1. Liver
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8
Q
  1. What is an enzyme that uses NADPH to produce ammonia for the urea cycle?
A
  1. Glutamate DH
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9
Q
  1. T or F: glutamate is a neurotransmitter
A
  1. True
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10
Q
  1. What are Asn and Gln deaminated by and what do they form from these deaminations?
A
  1. Asp, Glu via asparaginase and glutaminase
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11
Q
  1. What enzyme deaminates aspartate?
A
  1. AST
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12
Q
  1. What do tumor cells require for growth that can be inhibited in these pathways?
A
  1. Asparagine, inhibited by adding asparaginase which converts Asn to Asp
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13
Q
  1. What are Ser and Thr deaminated by?
A
  1. Ser and Thr dehydratase to pyruvate & a‐ketobutyrate respectively
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14
Q
  1. What is the only form of nitrogen that can pass through membranes?
A
  1. NH3
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15
Q
  1. What sites in the body is NH4+ released?
A
  1. Liver and kidney
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16
Q
  1. If the liver is damaged would NH3 levels rise?
A
  1. Yes without urea cycle it would accumulate
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17
Q
  1. How is urea in plasma measured?
A
  1. Blood urea nitrogen (BUN), typically 8‐20mg/dl
18
Q
  1. What can excess NH3 do to the body?
A
  1. Ammonia can be made into glu which can deplete brain of alphaketoglutarate causing
    OAA to fall and TCA to stopcell dmg; increased Glu can lead to Gln formation which
    depletes Glu and GABA (NT’s); brain swelling due to osmotic pressure
19
Q
  1. What enzyme in the Urea cycle adds nitrogen onto bicarbonate?
A
  1. CPSI using ATP
20
Q
  1. What enzyme adds carbomyl onto ornithine?
A
  1. Ornithine transcarbamolase
21
Q
  1. Where are the 2 enzymes aforementioned located?
A
  1. Mitochondria
22
Q
  1. What is the 3rd step in the urea cycle?
A
  1. Arginnosuccinate synthetase to form Argininosuccinate from asprate and citrulline
23
Q
  1. What is the 4th step?
A
  1. Arginnosuccinase to cleave fumarate from argininosuccinate
24
Q
  1. What is the 5th step?
A
  1. Arginase to cleave urea off argininosuccinate and produce ornithine (cycle is complete)
25
Q
  1. Where do steps 3‐5 take place?
A
  1. Cytosol
26
Q
  1. What is the overall reaction eqn. for urea cycle?
A
  1. NH4+bicarbonate+amino group of Asp+ATPurea+fumarate+ADP+AMP+PPi
27
Q
  1. How are the TCA and urea cycle linked?
A
  1. Via fumarate and alphaketoglutarate
28
Q
  1. How is most nitrogen carried in blood?
A
  1. Glutamine
29
Q
  1. Name two sources for NH3 in urea cycle
A
  1. Glutamine via glutaminase, alanine via ALT
30
Q
  1. What is the alanine cycle?
A
  1. Glu in muscle transaminated to Ala which is transferred to liver and converted to pyruvate for further metabolism
31
Q
  1. What type of hyperammonemia is genetic and most severe?
A
  1. Type 1
32
Q
  1. What type is late onset with liver cirrhosis?
A
  1. Type 2
33
Q
  1. What is an activator of CPS I?
A
  1. N‐acetyl glutamate
34
Q
  1. What synthesizes the answer to #458?
A
  1. N‐acetyl glutamate synthetase (NAGS)
35
Q
  1. What will a defect in NAGs lead to?
A
  1. Type 1 hyperammonemia
36
Q
  1. How can we treat hyperammonemia?
A
  1. Benzoate, pheylacetateremoves gly and Gln causes cell to utilize NH3 to
    resynthesize them
37
Q
  1. What are some characteristics of OTC deficiency?
A
  1. Increased carbomoyl phosphate, increased orotic acid (via CPSII in purine synthesis)
38
Q
  1. What is treatment for argininosuccinase deficiency?
A
  1. Increased arginine, reduced protein intake
39
Q
  1. What converts urea to carbonic acid and ammonia?
A
  1. Urease generated by bacterium proteus mirabilis
40
Q
  1. What is ppt’d as kidney stones?
A
  1. Magnesium ammonium phosphate
41
Q
  1. Where is the nitrogen in urea derived from?
A
  1. Aspartate and ammonia
42
Q
  1. What are some treatments for urea cycle deficiencies?
A
  1. Low protein intake (replace with a‐ketoacids), remove excess ammonia by using
    levulose to kill ammonia producing bacteria, administer sodium benzoate,etc.

5: MBOD Get Pumped haha (7 decks)

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