Disposal Of Ammonia And The Urea Cycle Flashcards

1
Q

The major source of ammonia for urea formation is

A

Ammonium ion (NH4)

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2
Q

Anaerobic respiration in the muscle could also produce ammonia via the __

A

AMP deaminase activity

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3
Q

What are the two pathways used to transport ammonia

A

1) glucose-alanine cycle
2) glutamine cycle

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4
Q

Glutamine cycle reaction is catalysed by an extra hepatic tissue enzyme called _

A

Glutamine synthetase

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5
Q

Organisms that secrete Their nitrogen as ammonia are collectively called _

A

Ammonotelic

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6
Q

Terestial animals that secrete their nitrogen as ammonia are called

A

Ureotelic

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7
Q

Birds that secrete their ammonia as Uric acid are called

A

Uricotelic

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8
Q

Urea cycle is also known as

A

Krebs-henseleit cycle

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9
Q

The quantity of urea excreted at any given time …

A

Is directly proportional to the total protein metabolism

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10
Q

The compartmentalization of reactions is necessary in order to

A

Bypass the feedback inhibition that would other wise interfere with urea biosynthesis in high ammonia concentration

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11
Q

What are the five reactions of the urea cycle

A

1) synthesis of carbamoyl phosphate
2) synthesis of citrulline
3) synthesis of argininosuccinate
4) cleavage of argininosuccinate
5) cleavage of arginine

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12
Q

What enzyme catalyses reaction 1 of the urea cycle ?

A

Carbamoyl phosphate synthetase 1

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13
Q

Enzyme of the second reaction

A

Ornithine carbamoyl transferase

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14
Q

The second urea nitrogen is formed in which reaction

A

The third (synthesis of argininosuccinate)

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15
Q

_ is the immediate precursor of urea

A

Arginine

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16
Q

The fourth reaction is catalyzed by _

A

Argininosuccinase OR argininosuccinate lyase

17
Q

Which enzyme of urea cycle is not found in the kidney or intestinal mucosa

A

Arginase

18
Q

The aspartate-argininosuccinate shunt entails

A

Fumarate is converted to Malate and then to Oxaloacetate

19
Q

The last reaction of urea cycle is catalysed by

A

Arginase

20
Q

__ is the rate limiting enzyme of the urea cycle

A

Carbamoyl phosphate synthetase 1