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Old 08-08-2011
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Biochemistry Outside the fibroblast during collagen synthesis

Collagen biosynthesis is a complex process that begins within fibroblasts and continues in the extracellular space. Which of the following processes occurs outside of the fibroblasts during collagen synthesis?

A) C-terminal propeptide removal
B) Lysine residue glycosylation
C) Proline residue hydroxylation
D) Terminal disulfide bond formation
E) Triple helix formation
F) Cleavage of hydrophobic N-terminal signal peptides
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D) Terminal disulfide bond formation
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Quote:
Originally Posted by Hope2Pass View Post
Collagen biosynthesis is a complex process that begins within fibroblasts and continues in the extracellular space. Which of the following processes occurs outside of the fibroblasts during collagen synthesis?

A) C-terminal propeptide removal
B) Lysine residue glycosylation
C) Proline residue hydroxylation
D) Terminal disulfide bond formation
E) Triple helix formation
F) Cleavage of hydrophobic N-terminal signal peptides


A) C-terminal propeptide removal
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E. Triple Helix Formation
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Quote:
Originally Posted by Hope2Pass View Post
Collagen biosynthesis is a complex process that begins within fibroblasts and continues in the extracellular space. Which of the following processes occurs outside of the fibroblasts during collagen synthesis?

A) C-terminal propeptide removal
B) Lysine residue glycosylation
C) Proline residue hydroxylation
D) Terminal disulfide bond formation
E) Triple helix formation
F) Cleavage of hydrophobic N-terminal signal peptides
a c-terminal propetide removal
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Old 08-08-2011
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Old 08-08-2011
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A) C-terminal propeptide removal
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Correct Answer A) C-terminal propeptide removal

The correct answer is A) C-terminal propeptide removal.

Explanation-

Procollagen is synthesized by a series of steps w\n the endoplasmic reticulum of cells such as fibroblasts. This molecule is then released into the extracellular space by transport through the Golgi appratus and converted into collagen by procollagen peptidases that cleave the water soluble, non-helical N- & C-terminal portions of the procollagen molecule to form collagen. Collagen monomers are then covalently crosslinked with each other after certain residues are oxidized by lysyl oxidase.

TO SUM IT UP -

Steps that occur INSIDE the fibroblast -
  • Hydroxylation of selected proline & lysine residues
  • Glycosylation of selected lysine residues
  • Assembly of pro-alpha-chains into triple helix

Then secretion of Procollagen into Golgi & Extrusion into extracellular matrix

Steps that occur OUTSIDE the fibroblast -
  • N- & C- terminal propeptide cleavage by propeptidase
  • Collagen fibril is formed
  • Covalent cross links formed by lysyl oxidase

And that ENDS the synthesis of Collagen!
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