blueocean
Forum Senior
Topics: 15
Posts: 195
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D- collagen fibers begin to assemble in the ER and Golgi complexes.
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| drpkaur
Forum Guru
Topics: 195
Posts: 808
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The correct answer is D. Collagen formation begins with transcription of mRNA from appropriate DNA genes in the nucleus. While still within the nucleus, the mRNA is spliced. It is then transported through the cytoplasm to the ribosomes on the rough endoplasmic reticulum. Individual chains are translated on the ribosomes, with the ends feeding into the endoplasmic reticulum lumen. Within the lumen, glycosylation of the individual chains occurs. The material then moves toward the Golgi bodies, whose lumens are connected to the endoplasmic reticulum, where the triple helices of procollagen form. The procollagen is then secreted into the extracellular space, where cleavage of pro-peptides and cross- linking of different triple helices occurs, maturing the collagen.
The centriole (choice A) is not a site of collagen synthesis.
The extracellular space (choice B) is the site of procollagen cleavage and cross- linking.
The nucleus (choice C) is the site of mRNA transcription and splicing.
The smooth endoplasmic reticulum (choice E) does not participate in collagen synthesis.
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