What constraints must be considered when encoding data into DNA sequences?

• A. GC content should be avoided completely for stability.
• B. Long homopolymers are encouraged to simplify synthesis.
• C. Balanced GC content, avoidance of long homopolymers and problematic motifs, and incorporation of error-correcting codes.
• D. No error-correcting codes are used in practice.

Answer: (C)

Encoding data into DNA requires balancing chemical stability with practical decoding. A sequence with balanced GC content maintains a reliable melting temperature and good stability without making synthesis or sequencing too difficult. Avoiding long homopolymers reduces the chance of errors during synthesis and sequencing, since repetitive stretches can slip or be misread. Steering clear of problematic motifs helps prevent unwanted secondary structures or patterns that complicate decoding or cause unintended biological effects. And including error-correcting codes provides a safety net to detect and correct mistakes that occur during synthesis, storage, or sequencing, ensuring data can be recovered accurately.

So, the best approach combines balanced GC content, avoidance of long homopolymers and problematic motifs, and the use of error-correcting codes. This contrasts with the idea of avoiding GC entirely, encouraging long homopolymers, or skipping error correction, all of which would undermine reliability and accuracy.