● An `color{violet}"elaborate network"` of `color{violet}"filamentous proteinaceous structures"` present in the cytoplasm is collectively referred to as the `color{Brown}"cytoskeleton"`.

● The cytoskeleton in a cell are involved in many functions such as `color{violet}"mechanical support"`, `color{violet}"motility"`, `color{violet}"maintenance of the shape"` of the cell.

● `color{Brown}"Cilia"` (sing.: cilium) and `color{Brown}"flagella"` (sing.: flagellum) are `color{violet}"hair-like outgrowths"` of the cell membrane.

● Cilia are `color{violet}"small structures"` which work like `color{violet}"oars"`, causing the movement of either the `color{violet}"cell or the surrounding fluid"`.

● Flagella are `color{violet}"comparatively longer"` and responsible for `color{violet}"cell movement"`.

● The `color{violet}"prokaryotic bacteria"` also possess `color{violet}"flagella"` but these are `color{violet}"structurally different"` from that of the `color{violet}"eukaryotic flagella"`.

● The `color{violet}"electron microscopic study"` of a cilium or the flagellum show that they are covered with `color{violet}"plasma membrane"`.

● Their `color{violet}"core"` called the `color{Brown}"axoneme"`, possesses a number of `color{violet}"microtubules"` running `color{violet}"parallel to the long axis"`.

● The axoneme usually has `color{Brown}"nine pairs of doublets"` of radially arranged `color{violet}"peripheral microtubules"`, and a pair of `color{violet}"centrally located microtubules"`.

● Such an arrangement of `color{violet}"axonemal microtubules"` is referred to as the `color{Brown}"9+2 array"`.

● The `color{violet}"central tubules"` are connected by `color{Brown}"bridges"` and is also enclosed by a `color{brown}"central sheath"`, which is connected to one of the tubules of each peripheral doublets by a `color{Brown}"radial spoke"`.

● Thus, there are `color{violet}"nine radial spokes"`.

● The `color{violet}"peripheral doublets"` are also interconnected by `color{Brown}"linkers"`.

● Both the `color{violet}"cilium and flagellum"` emerge from `color{violet}"centriole-like structure"` called the `color{Brown}"basal bodies"`.

● `color{Brown}"Centrosome"` is an organelle usually containing `color{violet}"two cylindrical structures"` called `color{Brown}"centrioles"`.

● They are surrounded by `color{violet}"amorphous pericentriolar materials"`.

● `color{violet}"Both the centrioles"` in a centrosome `color{Brown}"lie perpendicular"` to each other in which each has an `color{violet}"organisation like the cartwheel"`.

● They are made up of `color{violet}"nine evenly spaced"` peripheral fibrils of `color{Brown}"tubulin"`.

● Each of the `color{violet}"peripheral fibril"` is a `color{violet}"triplet"`.

● The `color{violet}"adjacent triplets"` are also linked.

● The `color{violet}"central part of the centriole"` is also `color{violet}"proteinaceous"` and called the `color{Brown}"hub"`, which is connected with tubules of the `color{violet}"peripheral triplet"`s by `color{violet}"radial spokes"` made of protein.

● The centrioles form the `color{violet}"basal body"` of `color{Brown}"cilia or flagella"`, and `color{violet}"spindle fibres"` that give rise to `color{Brown}"spindle apparatus"` during cell division in animal cells.