In the photosynthetic archaean Halobacterium halobium, a membrane transport protein called bacteriorhodopsin captures energy from sunlight and uses it to pump protons out of the cell
The resulting proton gradient serves as an energy store that can later be tapped to generate ATP. Which statement best describes how bacteriorhodopsin operates?
(a) The absorption of sunlight triggers a contraction of the ? barrel that acts as the protein's central channel, squeezing a proton out of the cell.
(b) The absorption of sunlight triggers a shift in the conformation of the protein's seven, membrane spanning ? helices, allowing a proton to leave the cell.
(c) The absorption of sunlight triggers a restructuring of bacteriorhodopsin's otherwise unstructured core to form the channel through which a proton can exit the cell.
(d) The absorption of sunlight triggers the activation of an enzyme that generates ATP.
(b)
You might also like to view...
What substance would you expect to accumulate in soil as a result of increased acid precipitation?
A. Calcium B. Nitrogen C. Oxygen D. Ammonia
Which of the following is not a type of microRNA?
A. Antisense RNA B. tRNA C. Riboswitch D. miRNA E. siRNA
Research on conditions that are relatively new to human populations such as myopia, breast cancer, and obesity support the conclusion that ________
A) human populations have accumulated a number of mutations that have become fixed by genetic drift B) the changes in human lifestyle account for all of the increase in frequencies of these conditions C) these conditions are indeed "diseases of civilization" and are likely caused by the interaction between genes (genetic susceptibility) and novel environments D) these human conditions are mere artifacts of the way in which they have been evaluated
Open reduction
What will be an ideal response?