The 9 + 2 arrangement refers to how the microtubules are organised in structures such as the flagella and cilia. It has 9 pairs of microtubules situated on the outside that are bound together and 2 pairs of microtubules in the middle that are not bound together. Attached to these doublet pairs, consisting of both microtubules in a fused pair, are dynein arms. These are motor proteins that create mechanical work energy from chemical energy acquired from ATP hydrolysis enabling movement along microtubules.
- ↑ The Biology project. Department of Biochemistry and Molecular Biophysics. Cytoskeleton Tutorial. September 1997 [cited 03/12/18] Available from: http://www.biology.arizona.edu/cell_bio/tutorials/cytoskeleton/page2.html
- ↑ Stephen M. King. Axonemal Dynein Arms. August 15, 2016 [cited 03/12/18] Available from: https://cshperspectives.cshlp.org/content/8/11/a028100.full