Explain the mechanisms of transport of substances across cell membranes including appropriate examples (75% marks). Outline the structure and function of the Na+/K+-ATPase pump (25% marks).
This question examined core cellular physiology knowledge. This knowledge is crucial as it underpins much of the electrochemical responses within the syllabus. Mechanisms of diffusion and the role of individual pathways were well presented in many responses. Answers that scored well generally classified the mechanisms of transport into active and passive processes which ensured an appropriate breadth of answer. Many answers failed to provide any examples which was requested. The structure of the Na+/K+ ATPase pump was less well described, however pleasingly most candidates were able to accurately articulate its role and function.
Now, for 25% of the mark, about that ATPase:
Wilson, David B. "Cellular transport mechanisms." Annual review of biochemistry 47.1 (1978): 933-965.
Yang, Nicole J., and Marlon J. Hinner. "Getting across the cell membrane: an overview for small molecules, peptides, and proteins." Site-Specific Protein Labeling. Humana Press, New York, NY, 2015. 29-53.
Stein, Wilfred. Transport and diffusion across cell membranes. Elsevier, 2012.
Cussler, E. L., Rutherford Aris, and Abhoyjit Bhown. "On the limits of facilitated diffusion." Journal of membrane science43.2-3 (1989): 149-164.
Wu, Ling-Gang, et al. "Exocytosis and endocytosis: modes, functions, and coupling mechanisms." Annual review of physiology 76 (2014): 301-331.
Clausen, Michael V., Florian Hilbers, and Hanne Poulsen. "The structure and function of the Na, K-ATPase isoforms in health and disease." Frontiers in physiology 8 (2017): 371.
Rice, William J., et al. "Structure of Na+, K+-ATPase at 11-Å Resolution: Comparison withCa2+-ATPase in E1 and E2 States." Biophysical Journal 80.5 (2001): 2187-2197.
Møller, Jesper V., Birte Juul, and Marc le Maire. "Structural organization, ion transport, and energy transduction of P-type ATPases." Biochimica et Biophysica Acta (BBA)-Reviews on Biomembranes 1286.1 (1996): 1-51.