It has now been over 30 years since J. D. Watson, F. H. C. Crick, and M. H. F. Wilkins established the double-stranded, helical nature of the DNA molecule and suggested how DNA serves in its own replication. According to their original model for DNA replication, the two polynucleotide chains of the "parent" double helix separate and each serves as [...]
Transcription is the synthesis of RNA using DNA as template. Transcription of DNA produces three types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). The initial RNA transcripts (called primary transcripts) contain many more bases than the final functional ribonucleic acid molecules; the extra nucleotides are removed by a mechanism called RNA processing. The net effect [...]
The fidelity with which DNA is replicated is very high, so that the order of base pairs in each daughter DNA molecule is identical to the original parent duplex. However, once replication is completed, the normal structure of the DNA molecule may be altered, thereby producing a form that cannot readily be replicated. For example, bases along one of the [...]