The long-flagella mutants (If1, lf2, lf3 and If4) of Chlamydomonas reinhardtii are defective in proteins that are required for the assembly of normal flagella, their phenotype being long flagella. In a previous study, we biophysically characterized these mutants for their waveform patterns, swimming speeds, beat frequencies and correlated these parameters with their flagellar lengths. We found an anomaly in this correlation and set out to explore the underlying molecular significance, if any. The diverse inner dynein isoforms are the flagellar motors that convert the chemical energy of ATP into the mechanical energy of motility; we probed the presence of one of these isoforms (DHC11, which might help in bend initiation) in the If mutants and compared it with the wild-type. Our studies show that the ratio of DHC11 is defective in the long-flagella mutants of Chlamydomonas reinhardtii. (C) 2016 Elsevier Inc. All rights reserved.