Transcript Document

Diatoms
• Eukaryotic algae
• Common type of
phytoplankton
• Unicellular or colonies
• Primary producers in the
food chain
• Over 200 genera of living
diatoms, and
approximately 100,000
species
• Found in freshwater and
marine environments
• Diatom cells are contained
within a unique silica cell wall
called frustules, comprising
two separate shells
– two shells overlap one other like
the two halves of a petri dish
•Silica is made in the cell
and then extruded to the
cell exterior and added to
the wall.
Reproduction
• When a diatom divides to produce two daughter
cells, each cell keeps one of the two halves and
grows a smaller half within it.
• After each division cycle the average size of
diatom cells in the population gets smaller.
• When a certain minimum size is reached, they
reverse this decline by expanding in size to give
rise to a much larger cell
– Caused by sexual reproduction.
Ecology
• Diatoms produce an estimated 20% to 25%
photosynthesis on the planet
• A major food resource for marine and
freshwater microorganisms and animal
larvae
• A major source of atmospheric
oxygen.
Nanotechnology
• The deposition of silica by diatoms may
also prove to be of utility to nanotechnology
• Diatom cells manufacture different shapes
and sizes, potentially allowing diatoms to
manufacture micro- or nano-scale structures
which may be of use in a range of devices,
including drug delivery