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Questions and Answers
Which type of collagen is primarily associated with tendon and corneal structures?
Which type of collagen is primarily associated with tendon and corneal structures?
What characterizes a triple-helical structure in collagen?
What characterizes a triple-helical structure in collagen?
What role do hydroxyproline and hydroxylysine play in collagen?
What role do hydroxyproline and hydroxylysine play in collagen?
Glycosylation in collagen biosynthesis is important for what reason?
Glycosylation in collagen biosynthesis is important for what reason?
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How many types of collagen are known to exist?
How many types of collagen are known to exist?
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What is the main function of fibril-associated collagens?
What is the main function of fibril-associated collagens?
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What is the primary structure of collagen defined by?
What is the primary structure of collagen defined by?
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Which types of collagen are classified as fibril-forming collagens?
Which types of collagen are classified as fibril-forming collagens?
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Degradation of collagen is generally associated with which physiological processes?
Degradation of collagen is generally associated with which physiological processes?
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What is the significance of the half-life of normal collagens?
What is the significance of the half-life of normal collagens?
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What initiates the formation of procollagen from pro-α chains?
What initiates the formation of procollagen from pro-α chains?
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Which enzymes are primarily responsible for the initial breakdown of procollagen?
Which enzymes are primarily responsible for the initial breakdown of procollagen?
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What is the outcome of the extracellular cleavage of procollagen?
What is the outcome of the extracellular cleavage of procollagen?
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Which part of the procollagen molecule is flanked by nonhelical amino acids?
Which part of the procollagen molecule is flanked by nonhelical amino acids?
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Which family of proteins is involved in the further degradation of collagen into amino acids?
Which family of proteins is involved in the further degradation of collagen into amino acids?
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What are the resulting fragments after the cleavage of procollagen?
What are the resulting fragments after the cleavage of procollagen?
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What role do propeptides play in the structure of procollagen?
What role do propeptides play in the structure of procollagen?
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What type of collagen can be specifically degraded by collagenases as mentioned in the content?
What type of collagen can be specifically degraded by collagenases as mentioned in the content?
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How does the collagen structure respond to tissue growth or injury?
How does the collagen structure respond to tissue growth or injury?
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What is the primary physiological role of α1-antitrypsin in the body?
What is the primary physiological role of α1-antitrypsin in the body?
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Which enzyme's activity is inhibited by α1-antitrypsin?
Which enzyme's activity is inhibited by α1-antitrypsin?
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Where is α1-antitrypsin primarily synthesized?
Where is α1-antitrypsin primarily synthesized?
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What characteristic makes alpha-keratins important in forming tough fibers?
What characteristic makes alpha-keratins important in forming tough fibers?
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What structural role do alpha-keratins play in the body?
What structural role do alpha-keratins play in the body?
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What is a key feature of α1-antitrypsin that contributes to its function in proteolytic inhibition?
What is a key feature of α1-antitrypsin that contributes to its function in proteolytic inhibition?
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What is the role of glycine in the structure of collagen?
What is the role of glycine in the structure of collagen?
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Which amino acids can undergo hydroxylation during collagen biosynthesis?
Which amino acids can undergo hydroxylation during collagen biosynthesis?
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What is required for the hydroxylation of proline and lysine in collagen?
What is required for the hydroxylation of proline and lysine in collagen?
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The repeating sequence found in collagen is denoted as Gly – X – Y. What does 'X' represent?
The repeating sequence found in collagen is denoted as Gly – X – Y. What does 'X' represent?
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What is the consequence of ascorbic acid deficiency in collagen synthesis?
What is the consequence of ascorbic acid deficiency in collagen synthesis?
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In collagen, what effect does glycosylation of hydroxylysine have?
In collagen, what effect does glycosylation of hydroxylysine have?
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Which cells are primarily responsible for the synthesis of collagen precursors?
Which cells are primarily responsible for the synthesis of collagen precursors?
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How does hydroxyproline contribute to collagen's structure?
How does hydroxyproline contribute to collagen's structure?
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What specific modification occurs to prepro-α chains during collagen synthesis?
What specific modification occurs to prepro-α chains during collagen synthesis?
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Collagen's triple-helical structure is primarily characterized by which of the following features?
Collagen's triple-helical structure is primarily characterized by which of the following features?
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What is the role of lysyl oxidase in collagen formation?
What is the role of lysyl oxidase in collagen formation?
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Which type of Ehlers-Danlos syndrome is most clinically important due to its impact on blood vessels?
Which type of Ehlers-Danlos syndrome is most clinically important due to its impact on blood vessels?
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What is a characteristic symptom of Osteogenesis Imperfecta Type II?
What is a characteristic symptom of Osteogenesis Imperfecta Type II?
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What mutation is associated with Osteogenesis Imperfecta Type I?
What mutation is associated with Osteogenesis Imperfecta Type I?
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Which of the following is NOT a characteristic feature of Ehlers-Danlos syndrome?
Which of the following is NOT a characteristic feature of Ehlers-Danlos syndrome?
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What is the primary defect in Menkes disease?
What is the primary defect in Menkes disease?
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Which cross-linking enzyme requires copper as a cofactor?
Which cross-linking enzyme requires copper as a cofactor?
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Which collagen type is primarily affected in Ehlers-Danlos syndrome?
Which collagen type is primarily affected in Ehlers-Danlos syndrome?
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What is a common complication observed in individuals with Osteogenesis Imperfecta?
What is a common complication observed in individuals with Osteogenesis Imperfecta?
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Which of the following results from the mutation of the amino acid sequence in collagen types I, III, or V?
Which of the following results from the mutation of the amino acid sequence in collagen types I, III, or V?
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Study Notes
Collagen
- Over 25 types of collagen identified, categorized into three main groups based on structure and function.
- Fibril-forming collagens (Types I, II, III) provide high tensile strength, forming supportive structures such as tendons and corneas.
- Network-forming and fibril-associated collagens serve different structural purposes in connective tissues.
Structure of Collagen
- Amino acid sequence rich in proline and glycine; repeating pattern of Gly-X-Y, where X is often proline and Y is hydroxyproline or hydroxylysine.
- Triple-helical structure formed by three polypeptide α-chains, contributing to collagen's fibrous and elongated shape.
- Hydroxyproline stabilizes the triple helix through interchain hydrogen bonds; not commonly found in other proteins.
Biosynthesis of Collagen
- Pro-α chains are synthesized in fibroblasts, osteoblasts, and chondroblasts and begin with an N-terminal signal sequence.
- Hydroxylation of proline and lysine is essential for stability, requiring enzymes, oxygen, iron, and vitamin C.
- Pro-α chains form procollagen which moves to the Golgi, where it is packaged and secreted.
- Extracellular cleavage by procollagen peptidases converts procollagen to tropocollagen, leading to fibril formation.
Collagen Degradation
- Collagen is highly stable with a long half-life, constantly remodeled by collagenases (metalloproteinases) in response to tissue growth or injury.
- Specific cleavage points lead to tropocollagen fragments, which are further degraded by proteinases.
Collagen Diseases (Collagenopathies)
- Ehlers-Danlos syndrome: Hereditary defect leading to a generalized connective tissue disorder affecting Types I, III, or V collagen. Symptoms include fragile skin and easy joint dislocations.
- Osteogenesis Imperfecta: Brittle bone syndrome causing fractures with minimal trauma. Two main types:
- Type I: Less severe, presenting in infancy with decreased collagen production.
- Type II: Most severe and fatal in utero or neonatally due to mutations in collagen genes.
α1-Antitrypsin and Elastin Degradation
- α1-antitrypsin (A1AT) acts as a protease inhibitor, particularly for neutrophil elastase that degrades elastin and other structural proteins.
- Predominantly synthesized in the liver, crucial for preventing tissue injury by controlling enzymatic activity in various tissues.
Alpha-Keratins
- Tough fibrous proteins found in hair, nails, and the outer layer of the epidermis.
- Constituent of intermediate filaments, distinguished by high cysteine content, providing disulfide bonds that enhance their insolubility and resistance to stretching.
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Description
Dive into the fascinating world of fibrous proteins with a focus on collagen. This quiz covers various types of collagen, including their structures and amino acid sequences, essential for understanding protein biology. Enhance your knowledge about collagen's unique triple-helical structure and its significance in biochemistry.
