Final answer:
The discrepancy in the phage chromosome coding for more amino acids than predicted by genome size is due to overlapping reading frames, which allow a single DNA strand to encode multiple proteins.
Step-by-step explanation:
The reason for the discrepancy between the actual number of amino acids (AA) encoded by the phage's chromosome, which is more than 2300 AA, and the predicted size of its genome, which should code for only 1795 AA, is overlapping reading frames. Unlike in enhancers, frameshift mutations, and alternative splicing, overlapping reading frames allow a single strand of DNA to encode more than one protein, depending on where the ribosomes begin translation. An overlapping gene is a gene whose expressible sequence partially overlaps with one or more other genes. The phenomenon of overlapping reading frames is common in the genomes of viruses including bacteriophages, which are known to have compact genomes with a high coding capacity.