Dr. Nagla El-Melegy: Protein Metabolism

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Questions and Answers

Where does oxidative deamination primarily take place?

Liver and kidney (correct)

Muscles and pancreas

Lungs and stomach

Brain and heart

What is the main reason for oxidative deamination?

To synthesize glucose

To provide NH3 for urea synthesis (correct)

To produce amino acids

To generate energy for the body

What is another outcome of oxidative deamination?

Production of fatty acids

Synthesis of cholesterol

Generation of ATP

Formation of α-keto acids (correct)

What is the role of α-keto acids in the body?

Participating in a variety of reactions (A) Signup and view all the answers

What is the byproduct of oxidative deamination that is used for energy generation?

α-keto acids (A) Signup and view all the answers

What is the significance of urea synthesis in the context of oxidative deamination?

It detoxifies the body by removing NH3 (A) Signup and view all the answers

What is the purpose of transamination in the context of amino acid metabolism?

To convert excess amino acids into energy (A) Signup and view all the answers

What is the result of transamination in terms of nitrogen concentration?

Nitrogen is concentrated in glutamate (C) Signup and view all the answers

What are the two types of processes involved in amino acid metabolism?

Catabolism and anabolism (A) Signup and view all the answers

What is the role of transamination in managing excess amino acids?

It breaks down excess amino acids into energy (B) Signup and view all the answers

What is the overall goal of amino acid metabolism?

To generate energy from amino acids (B) Signup and view all the answers

What is the typical range of amino acids found in proteins?

50 to 10,000 (D) Signup and view all the answers

What is a characteristic feature of amino acids?

Presence of NH2 group (D) Signup and view all the answers

What is the role of a-ketoglutarate in transamination reactions?

Amino group acceptor (B) Signup and view all the answers

What determines the sequence of amino acids in a protein?

Specific bodily DNA (C) Signup and view all the answers

What is the product of the transamination reaction catalyzed by aminotransferases?

New keto acid and new amino acid (B) Signup and view all the answers

Where are aminotransferases active?

Both in cytoplasm and mitochondria (B) Signup and view all the answers

What is the classification of a chain of 3 amino acids?

Tripeptide (A) Signup and view all the answers

What elements make up an amino acid?

Carbon, hydrogen, oxygen, nitrogen (B) Signup and view all the answers

What is the function of the PLP cofactor in transamination reactions?

Catalyzing the reaction (C) Signup and view all the answers

What is the general structure of an amino acid, as shown in the diagram?

NH2 - C - COOH (D) Signup and view all the answers

Study Notes

Amino Acids

Amino acids are organic acids that contain an NH2 group.
They are composed of carbon, hydrogen, oxygen, and nitrogen.
Chains of amino acids are classified as:
- Peptides: fewer than 50 amino acids
- Dipeptides: 2 amino acids
- Tripeptides: 3 amino acids
- Polypeptides: more than 10 amino acids
- Proteins: more than 50 amino acids (typically 100 to 10,000 amino acids linked together)

Transamination

Transamination is the reversible transfer of an amino group (in the form of ammonia) from an α-amino acid to an α-keto acid.
It forms a new amino acid and a new α-keto acid.
This process occurs mostly in the liver and kidney.
Transamination involves both catabolism (degradation) and anabolism (synthesis) of amino acids.
It diverts excess amino acids towards energy generation.
The amino acids undergo transamination to finally concentrate nitrogen in glutamate.

Metabolism of Amino Acids

Amino acids undergo certain common reactions, including transamination followed by deamination for the liberation of ammonia.
This process is involved in the production of non-essential amino acids.
The purpose of oxidative deamination is to provide NH3 for urea synthesis and α-keto acids for a variety of reactions, including energy generation.

Aminotransferases

Aminotransferases are active both in the cytoplasm and mitochondria.
They catalyze transamination reactions, where α-ketoglutarate acts as an amino group acceptor.
The reaction involves the transfer of an amino group from an amino acid to an α-keto acid, resulting in a new amino acid and a new keto acid.

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Description

This quiz covers the introduction to amino acids, digestion and absorption of proteins, as well as the fates of blood amino acids. Test your knowledge of protein metabolism with Dr. Nagla El-Melegy's course material.