Questions and Answers
What percentage of cellular dry weight do proteins make up?
Which term refers to the origin of the word 'protein'?
Who first suggested the name 'proteins' for organic compounds of utmost importance to life?
Which of the following descriptions best fits the classification of proteins?
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In what year did Mulder use the term 'proteins' for the high molecular weight nitrogen-rich substances?
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What distinguishes oxidative deamination from non-oxidative deamination?
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Which amino acids undergo non-oxidative deamination catalyzed by pyridoxal phosphate-dependent dehydrases?
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Which of the following correctly describes the transport forms of ammonia between tissues and the liver?
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What is the primary purpose of oxidative deamination?
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Which statement about metabolism of ammonia is correct?
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Study Notes
Overview of Amino Acids and Proteins
- Composed of twenty amino acids functioning as building blocks of life.
- Proteins, made from amino acids, are the most abundant organic molecules in living systems and account for 50% of cellular dry weight.
- Classified into simple, conjugated, and derived proteins.
Etymology of "Protein"
- "Protein" originates from the Greek word “Proteios,” meaning "holding first place."
- The term was suggested by Berzelius, a Swedish chemist, in reference to vital organic compounds.
Amino Acid Metabolism
- Deamination processes include oxidative and non-oxidative forms, occurring alongside transamination involving glutamate.
- Oxidative deamination releases free ammonia and occurs mainly in the liver and kidneys, providing ammonia for urea synthesis.
- Non-oxidative deamination releases ammonia without oxygen, impacting amino acids like serine, threonine, cysteine, and histidine.
Ammonia Transport and Metabolism
- Ammonia, formed from metabolic reactions, is transported as glutamine or alanine.
- Alanine is significant in the glucose-alanine cycle, transporting ammonia from muscles to the liver, while glutamine serves as a storage form of ammonia.
- Ammonia toxicity can disrupt ATP production in the brain.
Reversing Ammonia Toxicity
- IV sodium benzoate and phenyllactate can condense with glycine and glutamate to form excretable compounds.
- Hemodialysis may also be employed to remove excess ammonia from the body.
Urea Cycle
- Urea is the main end product of amino acid metabolism, synthesized in the liver and excreted via the kidneys.
- In renal failure, elevated blood urea results in hyperammonaemia; treatment may include antibiotics to reduce intestinal bacteria.
Clinical Significance of Blood Urea
- Normal blood urea levels range from 10-40 mg/dl; levels can rise due to a high-protein diet.
- Blood urea measurements help assess renal function, classifying increases into pre-renal, renal, and post-renal categories.
Non-Protein Nitrogen (NPN)
- NPN includes substances like urea, creatinine, and uric acid, indicating kidney function.
- NPN levels in healthy individuals typically range from 20-40 mg/dl.
Glycine Metabolism
- Glycine is a fundamental amino acid, prevalent in collagen, synthesized from serine and threonine.
- Functions include purine ring formation and glutathione synthesis, along with acting as a conjugating agent.
Treatment of Disorders Related to Amino Acid Deficiency
- Tyrosinosis, a rare disorder linked to tyrosine metabolizing enzyme deficiencies, requires dietary restrictions of methionine, phenylalanine, and tyrosine.
- Albinism arises from tyrosinase deficiency, inhibiting melanin production and increasing skin cancer risk due to sensitivity to sunlight.
Hypopigmentation
- Describes reduced melanin synthesis, contributing to conditions like albinism where individuals are at risk of photophobia and skin damage.
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Description
Explore the fascinating world of amino acids, the essential building blocks of life. This quiz covers their metabolism, structural organization, and related disorders. Test your knowledge on these fundamental components that play crucial roles in various biological processes.
