rough endoplasmic reticulum and smooth               Plastids
endoplasmic       reticulum.     The     rough
endoplasmic reticulum is covered with                Plastids are storage organelles. They store
ribosomes hence appears rough. They follow           products like starch for synthesis of fatty acids
the instructions from the nucleus and make           and terpenes.
proteins the cell needs. The smooth
                                                     History of research in Cell
endoplasmic reticulum is continuous with the
outer nuclear membrane. It transports material          1632–1723: Antonie van Leeuwenhoek
through the cell and produces and digests                teaches himself to make lenses, constructs
lipids and membrane proteins.                            basic optical microscopes and draws
                                                         protozoa, such as Vorticella from rain
Golgi apparatus
                                                         water, and bacteria from his own mouth.
They are flattened stacks of membrane bound             1665: Robert Hooke discovers cells in
sacs. They function as the packaging unit, the           cork, then in living plant tissue using an
proteins formed by the endoplasmic reticulum             early compound microscope. He coins the
are packed into small membrane sacs called               term cell (from Latin cella, meaning
vesicles.                                                "small room") in his book Micrographia
Vacuoles                                                1839: Theodor Schwann and Matthias
                                                         Jakob Schleiden elucidate the principle
They are organelles for storage. Small
                                                         that plants and animals are made of cells,
membrane bound vacuoles filled with fluids
                                                         concluding that cells are a common unit of
and water are present in animals. In plant cells
                                                         structure and development, and thus
the vacuoles perform functions of secretion,
                                                         founding the cell theory.
excretion and storage.
                                                        1855: Rudolf Virchow states that new
Chloroplasts                                             cells come from pre-existing cells by cell
                                                         division (omnis cellula ex cellula).
It is an elongated or disc-shaped organelle             1859: The belief that life forms can occur
containing chlorophyll. It is the site for               spontaneously (generatio spontanea) is
photosynthesis in a plant cell. The green                contradicted by Louis Pasteur (1822–
pigment chlorophyll absorbs energy from                  1895) (although Francesco Redi had
sunlight.                                                performed an experiment in 1668 that
                                                         suggested the same conclusion).
                                                        1931: Ernst Ruska builds the first
It is a network of fibers made up of micro-              transmission electron microscope (TEM)
tubule and micro-filament. They maintain the             at the University of Berlin. By 1935, he
shape and gives support to the cell.                     has built an EM with twice the resolution
                                                         of a light microscope, revealing previously
Plasmodesmata                                            unresolvable organelles.
                                                        1953: Watson and Crick made their first
They are microscopic channels which traverse
                                                         announcement on the double helix
the cell walls of plant cells and enables
                                                         structure of DNA on February 28.
transport and communication between them.
                                                        1981: Lynn Margulis published Symbiosis
                                                         in     Cell   Evolution     detailing     the
                                                         endosymbiotic theory.