Nitrogen Flashcards

1
Q

What are the main nitrogen containing molecuels in the body? (IMPORTANT)

A
Nucleic Acid
Nucleotides
Protein
Amines
Haem-containing groups
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2
Q

What is transamination?

A

When the amine group is transferred from one amino acid to a ketoacid to produce a new amino acid & ketoacid

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3
Q

Transamination is reversible what does this say about aminotransferases?

A

Theyre involved in amino acid breakdown & synthesis

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4
Q

What Cofactor do aminotransferases rely on to transfer the Amine group

A

Pyridoxal Phosphate Cofactor

(PLP) derived from vitamin B6

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5
Q

When do amino acids undergo oxidative catabolism?

A
  • When left over from protein synthesis
  • When excess from diet
  • When carbs are absent so muscle proteins are used for energy
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6
Q

How are proteins broken down to amino acids?

A

Proteins -> Peptides in stomach/small intestine by peptides

Peptides -> amino acids in small intestine

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7
Q

What happens to amino acids?

A

Broken to carbon skeletons & Ammonia

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8
Q

What are the 2 types of carbon skeleton?

A

Glucogenic

Ketogenic

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9
Q

What happens to glucogenic ones?

A

They enter gluconeogensis as oxaloacetate. Sometimes via the CAC to become oxaloacetate

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10
Q

What happens to ketogenic ones?

A

They become Acetyl-CoA so cant enter gluconeogenesis, they become ketone bodies.

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11
Q

What happens to the Ammonia from amino acids?

A

Used for biosynthesis of important nitrogen containing compounds
Any excess forms carbomoyl phosphate and enters the urea cycle

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12
Q

How is ammonia transported in the blood?

A

As alanine or glutamine

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13
Q

Why isnt ammonia just transported as glutamate?

A

BEcause its -ve so cant cross membranes

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14
Q

What happens to excess pyruvate in exercising muscle?

A

Some is converted to alanine by an amino transferase reaction with glutamate (made from muscle protein breakdown)

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15
Q

What ahppens to alanine made in muscles?

A

TRansported to the liver
Aminotransferase reaction produces pyruvate & glutamate again
- Pyruvate enters gluconeogenesis & as Glc is returned to muscle
- Glutamate enters urea cycle.

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16
Q

What are the 2 nitrogen acquiing reactions in the urea cycle?

A

Ammonia -> Carbamoyl phosphate

Aspartate + citrulline -> Arginosuccinate

17
Q

Which amino acids are both glucogenic & ketogenic?

A

Isoleucine
Tyrosine
Phenylalanine

18
Q

How many possible IMDs are there in the urea cycle?

A

6, one for each essential enzyme

19
Q

How are urea cycle IMDs inherited?

A
Autosomal Recessive
Except OTC (Ornithine Transcarbamoylase) deficiency which is X-linked.
20
Q

Which urea cycle IMD is most common?

A

OTC deficiency

21
Q

What is the main symptom of an IMD?

A

Hyperammonaemia

22
Q

Which 6 enzymes are involved in the urea cylce?

A

CPS1: Carbamoyl phosphate synthetase
OTC: ornithine +carbamyl phosphate -> citrulline
ASS - Argininosuccinate synthetase
ASL: Arginosuccinate Lyase
ARG: Arginase (arginine->ornithine + urea)
N-Acetylglutamate synthetase