def defineBiophysics(self):
        """Assign the membrane properties across the cell."""
        # Insert active Hodgkin-Huxley current in the soma
        self.soma.insert('hh')
        self.soma.gnabar_hh = 0.12  # Sodium conductance in S/cm2
        self.soma.gkbar_hh = 0.036  # Potassium conductance in S/cm2
        self.soma.gl_hh = 0.003    # Leak conductance in S/cm2
        self.soma.el_hh = -70       # Reversal potential in mV
        
        self.dend.insert('pas')
        self.dend.g_pas = 0.001  # Passive conductance in S/cm2
        self.dend.e_pas = -65    # Leak reversal potential mV
        self.dend.nseg = 1000
Assign the membrane properties across the cell.