Biochemistry LE 6: Amino Acids I (Catabolism of Amino Acids, C Skeleton, and the Urea Cycle)

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What is the primary function of amino acids in the body?

To synthesize proteins only

To generate metabolic energy (correct)

To break down larger molecules

To synthesize heme and other products

What is the major site of catabolic reactions in the human body?

The liver (correct)

The pancreas

The GIT

The kidneys

How many amino acids are nutritionally essential?

12

20

10

8 (correct)

What is the major component of purine and pyrimidine?

Amino acid Signup and view all the answers

What is the significance of nutritionally essential amino acids?

They require a large number of enzymes to biosynthesize Signup and view all the answers

What occurs in the body when it's in a fed state?

Anabolism Signup and view all the answers

What is the process of breaking down larger molecules?

Catabolism Signup and view all the answers

Which of the following amino acids is not required in adults?

Arginine Signup and view all the answers

What is a positive nitrogen balance accompanied by?

Growth and pregnancy Signup and view all the answers

How much dietary protein is taken in per day?

100 grams Signup and view all the answers

What is a negative nitrogen balance seen in?

Surgery, advanced cancer, kwashiorkor, and marasmus Signup and view all the answers

How much amino acids are produced from protein breakdown and consumed for protein synthesis?

250-300 grams Signup and view all the answers

What is BUN a measure of?

Urea-nitrogen balance Signup and view all the answers

What is the result of the equilibrium between dietary protein intake and protein synthesis?

A balance between protein synthesis and protein breakdown Signup and view all the answers

What is the purpose of amino acids in the body?

For generating metabolic energy, protein synthesis, and other functions Signup and view all the answers

When is BUN used to check?

To check for a hypercatabolic state Signup and view all the answers

What is the treatment for a hypercatabolic state?

Giving food supplements and other amino acids Signup and view all the answers

What is the relationship between dietary protein intake and protein synthesis?

Dietary protein intake equilibrates with protein synthesis Signup and view all the answers

What is the main goal of catabolism of amino acids?

To convert amino acids into energy or storage forms Signup and view all the answers

Which organ has all the pathways of amino acid synthesis and degradation?

Liver Signup and view all the answers

What is the fate of the carbon skeleton of every amino acid?

Convertible into either carbohydrate or fat or both Signup and view all the answers

What is the characteristic of ketogenic amino acids?

They produce ketone bodies Signup and view all the answers

Which amino acids are solely ketogenic?

Leucine and Lysine Signup and view all the answers

What is the characteristic of glucogenic amino acids?

They can be used for glucose synthesis Signup and view all the answers

What is the fate of the carbon skeletons of glucogenic amino acids?

They are degraded to TCA intermediates Signup and view all the answers

Which amino acids are both ketogenic and glucogenic?

Isoleucine, Phenylalanine, Tryptophan, and Tyrosine Signup and view all the answers

What is the relationship between the catabolic and anabolic pathways of amino acid metabolism?

They have separate regulation Signup and view all the answers

What is the consequence of impaired intestinal and renal transport of tryptophan in Hartnup disease?

Pellagra-like symptoms Signup and view all the answers

Which of the following enzymes is deficient in Classical Type PKU?

Phenylalanine hydroxylase Signup and view all the answers

What is the consequence of elevated homocysteine levels?

Oxidative damage, inflammation, and endothelial dysfunction Signup and view all the answers

Which amino acid can be synthesized in two pathways?

Methionine Signup and view all the answers

What is the role of the Kynurenine-anthranilate pathway in tryptophan metabolism?

Opens the indole ring that incorporates O2 Signup and view all the answers

What is the effect of folate, Vitamin B12, and B6 on homocysteine levels?

Decreases homocysteine levels Signup and view all the answers

What is the consequence of elevated homocysteine levels in pregnant women?

Increased incidence of neural tube defects Signup and view all the answers

Which essential amino acid is required to form a nonessential amino acid?

Methionine Signup and view all the answers

What is the substrate for the enzyme Hydroxyproline dehydrogenase in the catabolism of 4-hydroxy-L-proline?

4-hydroxy-L-proline Signup and view all the answers

What is the primary function of the TDO enzyme in tryptophan metabolism?

Opens the indole ring that incorporates O2 Signup and view all the answers

What is the product of the nonenzymatic reaction in the catabolism of 4-hydroxy-L-proline?

γ-hydroxy-L-glutamate-γ-semialdehyde Signup and view all the answers

What is the purpose of the Expanded Newborn Screening Test?

To detect early amino acid disorders Signup and view all the answers

What is one of the most common causes of cardiac arrest in younger patients?

Maple Syrup Urine Disease (MSUD) Signup and view all the answers

What is the by-product of DOPA that is important for the brain?

Tyrosine Signup and view all the answers

What is the deficiency that can cause Phenylketonuria (PKU)?

All of the above Signup and view all the answers

What is the product of the transaminase reaction in the catabolism of 4-hydroxy-L-proline?

ɑ-ketoγ-hydroxyglutarate Signup and view all the answers

What is the enzyme involved in the first step of the catabolism of 4-hydroxy-L-proline?

Hydroxyproline dehydrogenase Signup and view all the answers

What is the product of the aldolase reaction in the catabolism of 4-hydroxy-L-proline?

Glyoxylate + pyruvate Signup and view all the answers