What features distinguish a plant cell?In our everyday lives, it might seem pretty easy to distinguish
plants from animals, and in most cases it is. Things get a little shaky when we start
trying to classify bacteria, viruses, single cell marine organisms, etc. But if we stick
to the basics we can make some generalizations.
Plant cells differ from animal cells in two major ways:
- Plant cells are bounded by both a cell
membrane and a rigid cell wall, while animal cells are bounded by a cell membrane only.
- Plant cells contain structures called plastids. The most common plastids are chloroplasts (Gr. khloros -
greenish-yellow); these contain the green pigment chlorophyll
which is essential for photosynthesis. Animal cells do not contain plastids.
A typical plant cell consists of a relatively rigid cell
wall lined with a cell membrane. Within the membrane lie the nucleus and other structures
suspended in a liquid matrix called the cytoplasm.
Typical plant cell
The nucleus
is one of the larger structures in the cell; it has two important functions:
- It controls the ongoing activities of the
cell—serving as the "Mission Control."
- It contains the cell’s chromosomes, which store the
cell’s genetic information, and passes this information on to the daughter cells
during cell division.
Other important plant cell structures include:
- Vacuoles—filled with cell sap, a
liquid containing various salts and sugars; these help regulate the water balance in
cells.
- Plastids—contain various pigments and
other compounds. Plastids containing the green pigment chlorophyll are called
chloroplasts.
- Mitochondria—sites of cell respiration and the
production of energy used during cell functions.
- Ribosomes—the sites where proteins are
synthesized.
- Golgi bodies (one of my favorite botany
terms!)—a "packing and shipping" area in the cell.
- Endoplasmic reticulum—the communications
network linking the various structures of the cell; involved in the synthesis of various
substances important for growth and metabolism.
(This drawing represents a typical plant cell,
such as you might find in a leaf. Plants cells vary depending on their function; for
example, root cells don’t contain chloroplasts.)
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