Practice question

Question

A 1257 bp genomic DNA sequence of a prokaryotic gene was cloned under a strong constitutive promoter along with a suitable polyA signal and used for development of transgenic tobacco plants. Molecular analysis revealed the presence of three types/lengths of transgene derived mRNAs: 555 bp, 981 bp and 1257 bp - in the leaves of transgenic plants. The following statements were proposed to explain the above results. A. The three mRNAs represent alternatively spliced transcripts due to the presence of putative intronic sequence in the gene. B. The gene sequence was characterized by the presence of potential polyadenylation signals that resulted in premature termination of transcription. C. Expression of full-length transcripts (1257 bases) was lethal to the transformed cells. D. The transgenic plants were chimeric in nature and comprised of a mix of transformed and untransformed cells. Which of the following combinations of the above statements would correctly explain the obtained results?