muscles

Typically each end of a myosin filament has about 100 myosin molecules pulling in the same direction. Under physiological conditions each myosin can exert a force of about 5.3 pN. We get an upper bound on the force the filament can exert by assuming that all of the myosins are simultaneously attached and exerting force. Each myosin filament occupies a cross-sectional area of about 1.8*10^-15 square meters in the relaxed muscle. Use this data to estimate how much force your biceps can exert.

Ion pump energetics

Textbooks quote the value of standard free energy change for the hydrolysis of ATP equal to -7.3 kcal/mole. A certain molecular machine uses one ATP per ste and does useful work equal to 14 kT. Reconcile these statements, using the fact that typical intracellular concentration are [ATP] = 0.01, [ADP] = .001, and [Pi}= .01.

Why can a bumble bee only fly so high ?

Why can a bumble bee only fly so high ?