Cilia
 |
Figure 2-12 Cilia:
(a) whiplash and
(b) tinsel type |
Many microscopically sized plants and certain fungi contain hair like structures
that project out from the cell surface. These structures are used to propel
the cells through the water and are called
cilia or flagella. In many plants,
cilia or flagella are found only in sperm cells. There is little difference between
cilia and flagella except for length (flagella tend to be longer), and method of
movement. An electron microscope reveals the same structure for both. A
cross-sectional view of a cilium shows a circle of nine pairs of microtubules,
with two single microtubules in the center. Each microtubule possesses thirteen
longitudinal filaments. This structure is universal for all cilia and flagella
except those occurring in bacteria. Flagella and cilia grow out from an
organelle called the
basal body.
