Charlotte Jakes
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Nutrition and Metabolism Quiz on Amino Acid Metabolism, created by Charlotte Jakes on 31/12/2019.

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Charlotte Jakes
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Amino Acid Metabolism

Question 1 of 42

1

Body proteins are continuously degraded to amino acids and re-synthesised.

Select one of the following:

  • True
  • False

Explanation

Question 2 of 42

1

All proteins have the same half-lives.

Select one of the following:

  • True
  • False

Explanation

Question 3 of 42

1

Protein cannot be stored in the body.

Select one of the following:

  • True
  • False

Explanation

Question 4 of 42

1

Why is a high protein intake in an already well-fed individual wasteful?

Select one of the following:

  • Excess amino acids are catabolised and excreted as urea

  • Excess amino acids cause breakdown of glycogen

  • Excess amino acids cause fat accumulation

  • Excess protein will not be catabolised so will yield no energy

Explanation

Question 5 of 42

1

What is true of healthy adults?

Select one of the following:

  • Nitrogen intake = nitrogen excretion

  • Nitrogen intake > nitrogen excretion

  • Nitrogen intake < nitrogen excretion

Explanation

Question 6 of 42

1

When is a positive nitrogen balance (nitrogen intake > nitrogen excretion) required?

Select one of the following:

  • Growth in childhood, recovery after illness, after immobilisation, during pregnancy

  • During starvation, during serious illness, in injury and trauma

  • All the time - this is required for healthy adults

Explanation

Question 7 of 42

1

When might a negative nitrogen balance (nitrogen intake < nitrogen excretion) occur?

Select one of the following:

  • During starvation, during serious illness, in injury and trauma

  • Growth in childhood, recovery after illness, following immobilisation, during pregnancy

  • In normal circumstances - this is required for healthy adults

Explanation

Question 8 of 42

1

How are most cellular proteins degraded?

Select one of the following:

  • Ubiquitin breakdown system

  • Proteolytic enzymes in lysosomes

  • Proteolytic enzymes in the gut

  • Dissolve in the cytosol

Explanation

Question 9 of 42

1

How are exogenous proteins degraded?

Select one of the following:

  • Proteolytic enzymes in lysosomes

  • Ubiquitin breakdown system

  • Proteolytic enzymes in gut

  • Dissolve in cytoplasm

Explanation

Question 10 of 42

1

What is oxidative deamination?

Select one of the following:

  • The conversion of an amine group to a carbonyl group to form a keto acid from an amino acid

  • The transfer of an amine group from an amino acid to a keto acid

Explanation

Question 11 of 42

1

Which enzymes carry out oxidative deamination?

Select one of the following:

  • Dehydrogenases

  • Carboxylases

  • Oxidoreductases

  • Lyases

Explanation

Question 12 of 42

1

NADH + H+ are formed from NAD during oxidative deamination.

Select one of the following:

  • True
  • False

Explanation

Question 13 of 42

1

Oxidative deamination and transamination are reversible reactions.

Select one of the following:

  • True
  • False

Explanation

Question 14 of 42

1

What is a co-product of oxidative deamination?

Select one of the following:

  • Ammonia/ammonium ions

  • Pyruvate

  • Amino acids

  • FADH2

Explanation

Question 15 of 42

1

Fill the blank spaces to complete the text.

Fill in the blanks below to summarise oxidative deamination.
An amino acid reacts with to form a and . This is catalysed by a enzyme specific to that amino acid. This is a reaction that forms NADH and H+ from .

Explanation

Question 16 of 42

1

What is transamination?

Select one of the following:

  • The transfer of an amino acid to a keto acid to form a keto-carboxylate and another amino acid

  • The substitution of an amino group for a carbonyl group to form a keto acid and ammonia

Explanation

Question 17 of 42

1

What type of enzymes carry out transamination?

Select one of the following:

  • Transaminases

  • Dehydrogenases

  • Decarboxylases

  • Oxidoreductases

Explanation

Question 18 of 42

1

Fill the blank spaces to complete the text.

Fill in the blanks below to describe transamination.
An amino acid reacts with a to form a keto-carboxylate such as and the amino acid of the . This is carried out by enzymes in a reaction.

Explanation

Question 19 of 42

1

What are glucogenic amino acids?

Select one of the following:

  • Amino acids that can be converted back to glucose by the liver during starvation

  • Amino acids that can be degraded to acetyl CoA

  • Amino acids that can be incorporated into glycogen

  • Amino acids that stimulate glycogen degradation

Explanation

Question 20 of 42

1

What are ketogenic amino acids?

Select one of the following:

  • Amino acids that can be degraded to acetyl CoA

  • Amino acids that can be converted back to glucose by the liver during starvation

  • Amino acids that form ketone bodies in the blood

  • Amino acids that cause ketoacidosis

Explanation

Question 21 of 42

1

Which amino acids are ketogenic only?

Select one or more of the following:

  • Leucine

  • Lysine

  • Tyrosine

  • Iseoleucine

  • Phenylalanine

  • Histidine

  • Methionine

  • Alanine

  • Cysteine

Explanation

Question 22 of 42

1

Which amino acids are both glucogenic and ketogenic?

Select one or more of the following:

  • Tyrosine

  • Iseoleucine

  • Phenylalanine

  • Tryptophan

  • Threonine

  • Leucine

  • Lysine

  • Histidine

Explanation

Question 23 of 42

1

Only the liver can convert ammonia to urea for excretion in the urea cycle.

Select one of the following:

  • True
  • False

Explanation

Question 24 of 42

1

What does glutaminase do?

Select one of the following:

  • Form glutamate from glutamine

  • Form glutamate from alanine

  • Deaminate glutamate

  • Deaminate glutamine

Explanation

Question 25 of 42

1

What enzyme forms glutamine from glutamate?

Select one of the following:

  • Glutamine synthetase

  • Glutamate deaminase

  • Glutamate hydrolase

  • Glutamate carboxylase

Explanation

Question 26 of 42

1

Fill the blank spaces to complete the text.

When glutamate is formed from glutamine, the enzyme catalyses the reaction. This involves as a reactant and as a product.

Explanation

Question 27 of 42

1

Fill the blank spaces to complete the text.

When glutamine is formed from glutamate, ATP and are required. is hydrolysed to provide energy for the reaction. catalyses this reaction. Glutamine can carry ammonia equivalents in this way.

Explanation

Question 28 of 42

1

Why do we carry ammonia via glutamine to the liver for urea formation?

Select one of the following:

  • Carries 2 ammonia equivalents to prevent its toxic effects

  • The most soluble amino acid

  • Carries 3 ammonia equivalents to prevent its toxic effects

  • The most neutral amino acid

Explanation

Question 29 of 42

1

When ammonium ions combine with CO2/HCO3- in the mitochondria, what is formed?

Select one of the following:

  • Carbamoyl phosphate

  • L-Citruline

  • L-Aspartate

  • Urea

Explanation

Question 30 of 42

1

ATP hydrolysis is required for the synthesis of carbamoyl phosphate from CO2/HCO3- and ammonia.

Select one of the following:

  • True
  • False

Explanation

Question 31 of 42

1

What does carbamoyl phosphate combine with in the mitochondria to form citrulline?

Select one of the following:

  • Ornithine

  • Arginine

  • Fumarate

  • Arginosuccinate

Explanation

Question 32 of 42

1

What is lost when carbamoyl phosphate and ornithine react to form citrulline?

Select one of the following:

  • Inorganic phosphate

  • ATP

  • Methyl group

  • Carbonyl group

Explanation

Question 33 of 42

1

Which enzyme catalyses the formation of citrulline from carbamoyl phosphate and ornithine?

Select one of the following:

  • Ornithine transcarbamyolase

  • Ornithine pyrophosphatase

  • Citrulline synthetase

  • Carbamoyl pyrophosphatase

Explanation

Question 34 of 42

1

Where does citrulline combine with aspartate to form arginosuccinate?

Select one of the following:

  • Cytosol

  • Mitochondria

  • Plasma

  • Endoplasmic reticulum

Explanation

Question 35 of 42

1

Where does argininosuccinate synthase receive its energy to combine citrulline and aspartate to form argininosuccinate?

Select one of the following:

  • ATP hydrolysis

  • GTP hydrolysis

  • UTP hydrolysis

  • Concentration gradient of citrulline

Explanation

Question 36 of 42

1

What reaction forms arginine and fumarate from argininosuccinate?

Select one of the following:

  • Cleavage

  • Condensation

  • Phosphorylation

  • Dephosphorylation

Explanation

Question 37 of 42

1

What does the enzyme argininosuccinase do?

Select one of the following:

  • Cleave argininosuccinate into fumarate and arginine

  • Cleave argininosuccinate into malate and arginine

  • Dephosphorylate argininosuccinate

  • Phosphorylate argininosuccinate

Explanation

Question 38 of 42

1

What reaction converts arginine to urea and ornithine?

Select one of the following:

  • Hydration

  • Condensation

  • Phosphorylation

  • Dephosphorylation

Explanation

Question 39 of 42

1

What is required to convert arginine to urea and ornithine?

Select one of the following:

  • Water

  • Inorganic phosphate

  • Carbon dioxide

  • Bicarbonate

Explanation

Question 40 of 42

1

Fill the blank spaces to complete the text.

Fill in the blanks below to describe the ornithine/urea cycle.
1. Ammonium ions react with c or b in the . This forms . This reaction is catalysed by and requires hydrolysis.
2. combines with to form in the mitochondria. is lost in this reaction. This reaction is catalysed by .
3. is transported into the where it combines with to form . This is catalysed by and requires hydrolysis.
4. is cleaved into and arginine in a reaction catalysed by .
5. is hydrated and splits into urea and . This requires water and is catalysed by . The combines with more in the mitochondria to continue the cycle and the is excreted.

Explanation

Question 41 of 42

1

Fill the blank spaces to complete the text.

Fill in the blanks below to describe some of the end products of nitrogen metabolism.
Protein breakdown results in .
Creatine phosphate breakdown results in .
DNA and RNA breakdown results in .
The control of body pH results in .

Explanation

Question 42 of 42

1

Fill the blank spaces to complete the text.

Hyperammonaemia is caused by an impaired conversion of to . This can be caused by liver failure, for example in viral , c or other toxins. This can also be caused by genetic defects, for example causing mutations in the enzymes involved in the .
The symptoms of this include irratibility, headache and vomiting. In more severe cases hyperammonaemia can result in encephalopathy, seizures and ataxia.

Explanation

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