Q5Biology
Question
4 marks
Explain molecular basis of information transfer.
Answer
The molecular basis of information transfer follows the Central Dogma: DNA is replicated to pass genetic information, transcribed to RNA, and translated to protein, with information flowing from nucleic acid sequence to amino acid sequence.
- DNA Replication: the double helix is unwound by helicase; each strand serves as template; DNA polymerase adds complementary nucleotides (A-T, G-C) in 5' to 3' direction; result is two identical daughter DNA molecules (semi-conservative replication).
- Transcription: RNA polymerase binds the promoter on the template strand and synthesizes a complementary mRNA strand (A-U, T-A, G-C) reading 3' to 5'; produces pre-mRNA processed by capping, polyadenylation, and splicing in eukaryotes.
- Translation: ribosome reads mRNA codons (5' to 3'); aminoacyl-tRNAs deliver amino acids matching each codon; peptide bonds form between adjacent amino acids; terminates at stop codons; produces the polypeptide.