DNA is transcribed into a molecule of ______ which is then translated into proteins.

Question

BlackTom AI · Accepted Answer

DNA is transcribed into RNA, specifically messenger RNA (mRNA), which is then translated into proteins.

1. Relevant knowledge points and concepts
- Central dogma of molecular biology: DNA → RNA → Protein.
- Transcription: production of an RNA copy from a DNA template by RNA polymerase.
- Translation: decoding of mRNA codons at the ribosome with tRNA delivering amino acids to build a polypeptide.
- Base differences: RNA uses uracil (U) instead of thymine (T) found in DNA.

2. Step-by-step reasoning process
Step 1: A gene in DNA contains the sequence that encodes a protein. Step 2: RNA polymerase binds the promoter and synthesizes a complementary RNA strand (pre-mRNA in eukaryotes), matching A→U, T→A, C→G, G→C. Step 3: In eukaryotes the pre-mRNA is processed (5' cap, poly-A tail, splicing) to produce mature mRNA. Step 4: The mRNA exits the nucleus (eukaryotes) and associates with ribosomes. Step 5: During translation, the ribosome reads mRNA codons (three-nucleotide sequences); tRNAs with matching anticodons bring specific amino acids. Step 6: Amino acids are joined into a polypeptide that folds into a functional protein.

3. Calculations / intermediate steps
No numerical calculation is required. Intermediate biochemical steps are: DNA template → complementary RNA sequence (replace T with U) → processed mRNA → codon reading → amino-acid sequence assembly.

4. Why the correct answer is correct
RNA is the direct product of transcription from DNA and serves as the template for translation into proteins. Specifically, mRNA carries the genetic code from DNA to the ribosome where protein synthesis occurs.

5. Why other options are incorrect
- Lipid: lipids are a class of biomolecules (fats, membranes) and are not the direct transcription product of DNA for protein synthesis.  
- DNA: synthesis of DNA from DNA is replication, not the transcript used for making proteins.  
- Carbohydrates: sugars/polysaccharides are metabolic products, not the nucleic-acid intermediate used to code for proteins.

6. Conclusion
Therefore the correct answer is RNA, which matches the provided answer.

DNA is transcribed into a molecule of ______ which is then translated into proteins.单项选择题

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