Teaching Biophysics III. Biophysical approach of biomolecular motors

This work describes, in an accessible manner, the structures and functions of biomolecular motors. These motors are complex supra macromolecular structures which convert directly chemical energy into mechanical one and vice versa, accomplishing important cellular functions: chromosome migration during mitosis phase of cell cycles, DNA semiconservative duplication, vesicle transportation along filaments and tubules, etc. They can be classified as linear (e.g., actomyosin complex into sarcomeres, DNA helicase and DNA polymerase) and rotary motors (e.g., ATP synthase, prokaryotic flagella), eukaryotic undulating flagella and beating cilia (e.g., in eucaryotic cells). These nanomolecular motors are fuelled by ATP hydrolysis, although ATP synthase is driven by energy of a proton gradient performed by oxidative phosphorylation in mitochondria or by light in the case of thylakoids in plants and purple membrane of bacterium Halobacterium salinarum.