| Criteria | RNA Synthesis (Transcription) | Protein Synthesis (Translation) | Remarks |
| Definition | Process of synthesizing RNA from a DNA template | Process of synthesizing a polypeptide (protein) from an mRNA template | Both are central steps in gene expression, but occur in different stages and involve different molecular machinery. |
| Primary Location | Nucleus (in eukaryotes), cytoplasm (in prokaryotes) | Cytoplasm, specifically on ribosomes | Spatially separated in eukaryotes; coupled in prokaryotes. |
| Template | DNA | mRNA | Transcription uses DNA; translation uses RNA as a template. |
| End Product | RNA (mRNA, rRNA, tRNA, etc.) | Polypeptide chain (functional or structural proteins) | RNA is the immediate product of transcription; protein is the ultimate functional product of most genes. |
| Enzyme Involved | RNA polymerase | Ribosome (composed of rRNA and proteins), with assistance from tRNA | RNA polymerase reads DNA; ribosomes read mRNA and coordinate amino acid polymerization. |
| Direction of Synthesis | 5′ to 3′ direction on RNA strand; RNA polymerase reads DNA 3′ to 5′ | Polypeptide synthesized from N-terminal to C-terminal | Directionality is important for fidelity and processing. |
| Initiation Site | Promoter region on DNA | Start codon (AUG) on mRNA | Promoters regulate transcription start; AUG signals translation initiation. |
| Termination Signal | Terminator sequences (in DNA) | Stop codons (UAA, UAG, UGA) on mRNA | Termination is sequence-specific in both cases but mediated by different mechanisms. |
| Molecular Machinery | RNA polymerase, transcription factors, DNA template | Ribosomes, tRNAs, mRNA, aminoacyl-tRNA synthetases | Protein synthesis involves more complex macromolecular coordination. |
| Base Components | Nucleotides (ATP, GTP, CTP, UTP) | Amino acids | Transcription uses ribonucleotides; translation uses amino acids to build proteins. |
| Product Modifications | Capping, polyadenylation, and splicing (in eukaryotic mRNA) | Folding, post-translational modifications (e.g., phosphorylation, glycosylation) | mRNA and proteins often undergo extensive processing before becoming functional. |
| Energy Requirement | Requires energy (ATP, NTP hydrolysis during RNA chain elongation) | Requires GTP for peptide bond formation and ribosome translocation | Both are energy-intensive processes critical for gene expression. |
| Fidelity Mechanism | Proofreading by RNA polymerase (limited) | Ribosomal accuracy via codon-anticodon pairing and tRNA selection | Translation is more error-prone but uses kinetic proofreading to maintain fidelity. |
| Types of Products | mRNA, tRNA, rRNA, and regulatory RNAs | Structural, enzymatic, or regulatory proteins | Transcription generates various RNA types, not just mRNA. |
| Speed of Process | Fast; about 40–50 nucleotides per second in prokaryotes | Slower; ~3–5 amino acids per second in eukaryotic cells | Translation is generally slower due to complexity and accuracy requirements. |
| Regulation | Transcription factors, enhancers, repressors, chromatin remodeling | Initiation factors, mRNA availability, ribosome availability, upstream ORFs | Both steps are tightly regulated at multiple levels to control gene expression. |
| Coupling with Other Processes | Coupled with splicing and RNA processing in eukaryotes | Often coupled with folding and chaperone-mediated modifications | In prokaryotes, transcription and translation are often simultaneous (coupled). |
| Biological Importance | First step in gene expression; converts DNA-encoded information into RNA | Final step in gene expression; converts RNA code into functional proteins | Together, transcription and translation allow the flow of genetic information: DNA → RNA → Protein (Central Dogma). |
| Errors and Consequences | Can lead to incorrect RNA sequence, affecting protein translation | Errors result in faulty proteins, potentially leading to disease | Both processes must be highly accurate for normal cellular function. |
| Experimental Applications | RT-PCR, RNA-seq, transcriptional profiling | In vitro translation assays, ribosome profiling, proteomics | Widely used in molecular biology, diagnostics, and synthetic biology. |
