82. A mammalian cell culture is treated with cycloheximide. Protein synthesis of cells after treatment was
recorded through incorporation of labeled amino acids. In which of the following organelles will fresh
protein synthesis be detected?
1. Nucleus
2. ER
3. Mitochondria
4. Golgi
Effect of Cycloheximide on Protein Synthesis in Organelles
Cycloheximide is a widely used antibiotic that inhibits protein synthesis by blocking the elongation phase of translation in eukaryotic cells. This means that after treatment with cycloheximide, protein synthesis is generally halted in the cytoplasm.
However, cycloheximide does not affect protein synthesis in all organelles. Some organelles have their own translation machinery that is resistant to cycloheximide:
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Nucleus: The nucleus does not carry out protein synthesis. Protein synthesis primarily occurs in the cytoplasm and mitochondria.
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Endoplasmic Reticulum (ER): The ER is involved in protein folding and post-translational modifications but does not have an independent translation mechanism that would be unaffected by cycloheximide.
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Mitochondria: Unlike other organelles, mitochondria possess their own ribosomes and translation machinery. This allows them to continue protein synthesis even in the presence of cycloheximide.
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Golgi Apparatus: The Golgi apparatus is involved in modifying and packaging proteins but does not perform protein synthesis. Therefore, it will not carry out fresh protein synthesis after cycloheximide treatment.
Conclusion:
In a mammalian cell culture, after treatment with cycloheximide, fresh protein synthesis will still be detected in mitochondria, as they possess an independent translation system.
Correct answer: Mitochondria
This article provides insights into how cycloheximide selectively impacts protein synthesis in different organelles within mammalian cells.
