Question

Which one of the following statements about axonemes is incorrect?

1) Dynein motor proteins on each A tubule contact the neighboring B-tubule and move in an ATP-dependent manner.
2) The axoneme has stabilizing proteins to maintain structure, and motor proteins to facilitate movement.
3) The B-tubule of each of the 9 doublets is made up of 13 protofilaments.
4) One of the microtubules in each doublet is a complete microtubule, while the other is an incomplete microtubule.
5) The axoneme has its minus end anchored to the basal body.

Answer 1

The incorrect statement about axonemes is that the B-tubule of each of the nine doublets is made up of 13 protofilaments; instead, it is composed of 10 or 11 protofilaments.

Step-by-step explanation:

The question asks to identify the incorrect statement about axonemes. Axonemes are complex microtubular structures found in eukaryotic cilia and flagella, comprising a core of nine doublet microtubules surrounding two central single microtubules in a 9+2 arrangement. Statement 3 is incorrect; the B-tubule of each of the nine doublets is made up of 10 or 11 protofilaments, not 13. Every A-tubule, however, is made up of 13 protofilaments

. Dynein motor proteins facilitate movement by walking along the B tubules of an adjacent doublet in an ATP-dependent manner, causing the cilium or flagellum to bend due to the sliding of microtubules past each other. The axoneme is indeed anchored to the basal body at its minus end, and there are stabilizing proteins like nexin and radial spoke proteins that help maintain its structure.