The process of gene expression can be broken down into several key steps, which occur in a specific order. Here is the correct sequence:
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Transcription: The first step involves the synthesis of messenger RNA (mRNA) from a DNA template. RNA polymerase binds to the promoter region of the gene and unwinds the DNA, synthesizing a complementary RNA strand based on the DNA sequence.
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RNA Processing: In eukaryotic cells, the primary mRNA transcript undergoes several modifications before it can be translated. These modifications include the addition of a 5’ cap, the addition of a poly-A tail at the 3’ end, and splicing to remove introns (non-coding regions) while joining the exons (coding regions).
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Export from the Nucleus: The processed mRNA is then transported from the nucleus to the cytoplasm through the nuclear pore.
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Translation: In the cytoplasm, the mRNA is translated into a polypeptide (protein) by ribosomes. Transfer RNA (tRNA) molecules bring amino acids to the ribosome, where the mRNA sequence is read in codons (three nucleotides at a time) to assemble the corresponding amino acids into a protein.
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Post-Translational Modifications: After translation, proteins may undergo further modifications, such as phosphorylation, glycosylation, or cleavage, which are crucial for their final functional forms and activities.
This sequence—transcription, RNA processing, export, translation, and post-translational modifications—represents the essential steps of gene expression.