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Urea Cycle Flashcards

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1
Q

Protein catabolism leads to ________, which enters the Citric Acid Cycle.

A

Acetyl CoA

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2
Q

True or False: Only some of the 20 amino acids contain nitrogen

A

False; all 20 contain nitrogen

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3
Q

Proteins first breakdown into _______, and then into _______ to enter the citric acid cycle.

A

Amino acids; acetyl coa

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4
Q

What is nitrogen metabolism?

A

A conserved process whereby the nitrogen is split apart from the carbon structure

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5
Q

How do cells process nitrogen?

A

Cells process nitrogen by using the Urea Cycle to excrete this element, preventing toxic build up.

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6
Q

NADH yields ___ ATP.

A

2.5

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7
Q

FADH2 yields ___ ATP

A

1.5

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8
Q

What’s the importance of molecules NADH and FADH2?

A

They donate their electrons and hydrogen atoms to the electron transport chain, where formation of ATP happens.

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9
Q

Is energy production is direct or not direct?

A

Not direct

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10
Q

Energy production is a result of what?

A

electrons flowing through the ETC consuming O2 and producing H2O, which permits ATP formation.

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11
Q

This complex series of events leading to ATP production is described by?

A

chemiosmotic theory (a grand unifying theory in science)

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12
Q

When does nitrogen become toxic?

A

Nitrogen becomes toxic if built up in cells

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13
Q

True or False: Amino acids are broken down to acetyl coA through multiple pathways.

A

True

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14
Q

Does a different side chain equate to a different pathway?

A

Yes

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15
Q

Carbon from amino acids degrades to?

A

acetyl coA

This is similar to the degradation of carbohydrates and fatty acids

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16
Q

Acetyl CoA —> ___________ —-> ___________________

A

Citric Acid Cycle, Oxidative phosphorylation

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17
Q

What is the carbon portion of an amino acid called?

A

carbon skeleton, which is the structural framework

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18
Q

All 3 of these atoms yield acetyl-CoA

A

carbon, hydrogen, and oxygen

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19
Q

Which atoms are dealt with in the breakdown process by specific processes of enzymes?

A

nitrogen, sulfur, and other atoms.

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20
Q

Degradation of ALL amino acids involve what?

A

a step of deamination

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21
Q

What is deamination?

A

the removal of amine functional groups, resulting in ammonium (NH4+)

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22
Q

What else happens during deamination, besides the removal of amine functional groups, producing nH4+?

A

Nitrogen separates from carbon portion of molecules

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23
Q

True or false: NH4+ and carbon atoms follow different catabolic pathways after deamination

A

True

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24
Q

List the order in which events occur:

Carbon skeleton

ATP

Proteins

Acetyl CoA

Amino Acids

Oxidative Deamination

A
  1. Proteins
  2. Amino Acids
  3. Oxidative Deamination
  4. Carbon Skeleton
  5. Acetyl CoA
  6. ATP
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25
NH4+ is produced by _____________
oxidative deamination
26
Nitrogen is processed in which cycle?
the urea cycle
27
What is the urea cycle?
a 4 step cylic process that converts NH4+ (ammonium) to Urea, which is then excreted from the body.
28
once NH4+ is removed, NH4+ is acted upon in the mitochondria by which enzyme? In which reaction does this occur?
carbamoyl phosphate synthetase 1 Reaction A
29
In reaction A, how many ATP molecules are invested, and what does that highlight?
2 ATP molecules are invested, which highlight the importance of processing and excreting nitrogen.
30
Carbamoyl phosphate synthetase 1 acts upon NH4+ to form ______________, which can enter the ____________.
carbamoyl phosphate, urea cycle.
31
In Urea Cycle, carbamoyl phosphate reacts with _________.
ornithine (an amino acid that isn't apart of the 20 amino acids found in protein structure).
32
Where in the cell does carbamoyl phosphate react with ornithine?
within the mitochondria matrix
33
Carbamoyl phosphate and ornithine react to form ..
Citrulline
34
What part of the cell is citrulline sent to?
Citrulline is exported to cytosol
35
Which 2 things does citrulline react with in the cytosol?
ATP and Asparate
36
Citrulline reacts with ______ and ______ to produce ___________.
ATP, Asparate, Arginosuccinate
37
During the reaction between citrulline, atp, and asparate, what is ATP doing?
energy in the form of ATP fuels this reaction
38
What does ATP produce in reaction 2
AMP and PPi, which is inorganic pyrophosphate (P2O74-)
39
what regenerates into ATP by other cellular processes?
AMP regenerates to ATP
40
which enzyme acts in reaction 2?
Argininosuccinate synthetase
41
What is the result of citrulline reacting with ATP and Asparate and acted upon by enzyme Argininosuccinate synthetase?
Argininosuccinate
42
What does a synthetase do?
This enzyme joins molecules together in a synthesis reaction
43
In Reaction 3, Argininosuccinate is degraded by which enzyme?
Argininosuccinase
44
In reaction 3, Argininosuccinate is acted upon by argininosuccinase (enzyme) and produces what two things?
fumarate arginine
45
Fumarate is a component of the __________
Citric Acid Cycle
46
Where does the Citric Acid Cycle take place in a cell?
mitochindria
47
Fumarate can take the path of Citric Acid cycle ONLY AFTER it is converted to ________
malate
48
Arginine contains ___ nitrogen atoms on its side chain and ___ nitrogen atom on its backbone structure
2 nitrogen atoms on side chain 1 nitrogen atom on backbone
49
Arginine is cleaved (split) by enzyme _____________to produce these 2 things: ___________ and __________
arginine is cleaved by enzyme arginase to produce these 2 things: urea and ornithine
50
Which part of arginine is apart of urea?
2 nitrogen atoms from side chains are apart of urea.
51
How is urea excreted from the body?
in Urine
52
Why is Urea an excellent molecule to export nitrogen from the cell?
1. Urea has a high water solubility due to its hydrogen bonding ability 2. Urea has a high density of nitrogen atoms in just a small molecule
53
Urea is excreted from the body in urine ,and ornithine goes where ? to do what?
Ornithine goes to the mitochondrion to enter cycle again
54
Where is ornithine produced in the cell?
cytosol
55
When ornithine leaves the cytosol to enter the cycle again, what does it react with in the 1st reaction? what do the two create?
carbamoyl phosphate citrulline
56
in reaction 1, which enzyme is present in the reaction between ornithine and carbamoyl phopshate, creating citrulline?
Ornithine transcarbamoylase
57
Urea cycle happens mostly in what two organs of the body?
liver and kidneys
58
which part of an amino acid is handled by the Urea Cycle?
H3N
59
In Reaction A, there's NH4+ HCO3- and 2 ATP; what is HCO3-?
Bicarbonate
60
Nitrogen is really:
free ammonia
61
In reaction A, nitrogen is converted to an organic compound called _________ so that it can enter the urea cycle to be excreted.
carbamoyl phosphate
62
True or False: Ornithine is only found in the urea cycle.
False, ornithine is found in both the urea cycle and citric acid cycle.
63
True or False: NH4+ (ammonium) is highly toxic to animal tissue
True
64
True or False: A mutation or defect in one of the enzymes in urea cycle is safe
False; a mutation or defect in one of the enzymes in urea cycle can have serious, fatal consequences.
65
Individuals with deficiencies or mutations in enzymes within urea cycle cannot handle diets high in ___________. They must follow a strict diet.
protein
66
Inorganic phosphate (Pi) is: Inorganic pyrophosphate (PPi) is:
Inorganic phosphate is produced in reaction A and released in Reaction 1 Inorganic pyrophosphate is produced in reaction 2 (P2O74-)
67
In which step does ATP produce AMP + PPi?
Reaction 2
68
In which step is the first investment of ATP?
Reaction A (2 ATP CONVERTED TO 2 ADP + Pi)
69
In which step is the second investment of ATP?
Reaction 2 (1 ATP CONVERTED TO AMP + PPi )
70
Citrullineamia occurs at reaction __.
2.
71
Citrullineamia is the result of a mutation in the __________________ enzyme in reaction 2 and doesn't allow for citrulline to efficiently form argininosuccinate.
argininosuccinate synthetase
72
Argininosuccinate aciduria is the result of a mutation in the ____________ enzyme in reaction 3 and doesn't allow efficient secretion (causing buildup of ammonium)
Argininosuccinase
73
arginaemia is the result of a mutation in the ____________ enzyme in reaction 4 and doesn't allow efficient secretion (causing buildup of ammonium)
Arginase
74
True or False: All of these urea cycle diseases cause a build up of ammonium, which can become toxic.
True

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