a) The consensus sequence that connects the ribonucleic acid (RNA) polymerase to the deoxyribonucleic acid (DNA) is not the same for both prokaryotes and eukaryotes. The sequence for yeast would be the TATA box located at -30 positions, whereas in prokaryotes the consensus sequence is located between -35 and -10 locations. Hence, yeast promoter would not work in a prokaryotic system.
b) The size of the mRNA produced in E. coli would be twice the length as opposed to those produced inside yeast. This is because of the fact that the eukaryotic genes would be interspersed with introns along with the requisite exons. Other factor that could add up to the length of the mRNA molecule is that the termination sequence of the yeast cell would not be recognized by the E. coli cell.