Question

2 a) Lactose permease uses dissipation of a proton gradient as an energy source to import lactose into the cell. How is this achieved? Describe the mechanism. 2 PTS b) Another active transporter is the P-type ATPase SERCA. The transport mechanism of SERCA is quite different from lactose permease. However, here, please describe common features of the transport mechanism of Lactose permease and SERCA (hints: how do the transported substrates cross the membrane? How is it ensured that the energy-consuming reaction actually results in transport and not in energy loss)? 2PTS Word limit 300 words

Answer 1

a .Lactose permease is a symporter which is used to transport lactose alongwith hydrogen ions . It is called facilitated diffusion , and occurs along the concentration gradient.

b.SERCA is a smooth endoplasmic reticulum calcium ATPase

It transports calcium from cytoplasm to smooth endoplasmic reticulum..energy is derived from ATP. Phospholamban a regulatory protein regulates the calcium transport..

In both substrate binds to the site and conformational change occurs in the carrier protein and substrate is carried to other side. Conformational change does not occur unless substrate is binded.