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Question
Radioactively labeled amino acids introduced into a growing cell culture would be incorporated by the cells. If the cells were involved in protein synthesis and secretion. Select the order of organelles in which the labeled amino acids would appear over the time period.
Radioactively labeled amino acids introduced into a growing cell culture would be incorporated by the cells. If the cells were involved in protein synthesis and secretion. Select the order of organelles in which the labeled amino acids would appear over the time period.
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Solution
The correct option is B Rough endoplasmic reticulum - smooth endoplasmic reticulum - golgi apparatus - plasma membrane
The endoplasmic reticulum is a network of membrane-enclosed tubules and sacs (cisternae) which extends from the nuclear membrane throughout the cytoplasm. The introduction of radioactively labelled amino acids into a growing culture of cells involved in protein synthesis is an experiment undertaken to trace the pathway taken by secreted proteins. Auto-radiographic studies of the radio-labeled proteins which had incorporated the radioactive amino acids reveals that the newly synthesized proteins were detected in the rough ER, identified as the site of protein synthesis and secretion. Once the proteins become bound to the rough endoplasmic reticulum, the proteins enter or cross the ER membrane during their synthesis. While some are inserted into the rough ER membrane, others localize in the membranes of the smooth ER or Golgi apparatus. Further incubation in the media containing nonradioactive amino acids, the radiolabeled proteins were found in the Golgi apparatus which then traveled to the secretory vesicles and then fused with the plasma membrane to release this outside the cell. Thus, the correct answer is option B.
The endoplasmic reticulum is a network of membrane-enclosed tubules and sacs (cisternae) which extends from the nuclear membrane throughout the cytoplasm. The introduction of radioactively labelled amino acids into a growing culture of cells involved in protein synthesis is an experiment undertaken to trace the pathway taken by secreted proteins. Auto-radiographic studies of the radio-labeled proteins which had incorporated the radioactive amino acids reveals that the newly synthesized proteins were detected in the rough ER, identified as the site of protein synthesis and secretion. Once the proteins become bound to the rough endoplasmic reticulum, the proteins enter or cross the ER membrane during their synthesis. While some are inserted into the rough ER membrane, others localize in the membranes of the smooth ER or Golgi apparatus. Further incubation in the media containing nonradioactive amino acids, the radiolabeled proteins were found in the Golgi apparatus which then traveled to the secretory vesicles and then fused with the plasma membrane to release this outside the cell. Thus, the correct answer is option B.
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