In a study of proteins mediating cell membrane transport, biologists measure current versus time through the cell membranes of oocytes (nearly mature egg cells) taken from the african clawed frog, xenopus. the measured current versus time is given approximately by = + 2 + 4. 3 with t in seconds and in na. find the total charge that flows through the cell membrane in the interval from t=0 and t=5.0 s