A 2-kb fragment of E. coli DNA contains the complete sequence of a gene for which transcription is terminated by the rho protein. The fragment contains the complete promoter sequence as well as the terminator region of the gene. The cloned fragment is examined by band shift assay (see Research Technique 8.1). Each lane of a single electrophoresis gel contains the 2-kb cloned fragment under the following conditions: Lane 1: 2-kb fragment alone Lane 2: 2-kb fragment plus the core enzyme Lane 3: 2-kb fragment plus the RNA polymerase holoenzyme Lane 4: 2-kb fragment plus rho protein Explain the relative positions of bands in lanes 1 and 4.