Plant cells are
eukaryotic cells
, or cells with a membrane-bound nucleus. Unlike
prokaryotic cells
, the
DNA
in a plant cell is housed within the nucleus. In addition to having
a nucleus, plant cells also contain other membrane-bound organelles, or
tiny cellular structures, that carry out specific functions necessary
for normal cellular operation. Organelles have a wide range of
responsibilities that include everything from producing hormones and
enzymes to providing energy for a plant cell.
Plant cells are similar to
animal cells
in that they are both eukaryotic cells and have similar organelles.
Plant cells are generally larger than animal cells. While animal cells
come in various sizes and tend to have irregular shapes, plant cells are
more similar in size and are typically rectangular or cube shaped. A
plant cell also contains structures not found in an animal cell. Some of
these include a
cell wall
, a large vacuole, and plastids. Plastids, such as
chloroplasts
, assist in storing and harvesting needed substances for the plant. Animal cells also contain structures such as
centrioles
,
lysosomes
, and
cilia and flagella
that are not typically found in plant cells.
Plant Cell: Structures and Organelles
The following are examples of structures and organelles that can be found in typical plant cells:
- Cell (Plasma) Membrane - a thin, semi-permeable membrane that surrounds the cytoplasm of a cell, enclosing its contents.
- Cell Wall - outer covering of the cell that protects the plant cell and gives it shape.
- Chloroplast - the sites of photosynthesis in a plant cell. They contain chlorophyll, a green pigment that absorbs energy from sunlight.
- Cytoplasm - gel-like substance within the cell membrane containing water, enzymes, salts, organelles, and various organic molecules.
- Cytoskeleton - a network of fibers throughout the cytoplasm that helps the cell maintain its shape and gives support to the cell.
- Endoplasmic Reticulum (ER) - extensive network of membranes composed of both regions with ribosomes (rough ER) and regions without ribosomes (smooth ER).
- Golgi Complex - responsible for manufacturing, storing and shipping certain cellular products.
- Microtubules - hollow rods that function primarily to help support and shape the cell.
- Mitochondria - this organelle generates energy for the cell.
- Nucleus - membrane bound structure that contains the cell's hereditary information.
- Nucleolus - structure within the nucleus that helps in the synthesis of ribosomes.
- Nucleopore - tiny hole within the nuclear membrane that allows nucleic acids and proteins to move into and out of the nucleus.
- Peroxisomes
- tiny structures bound by a single membrane that contain enzymes that
produce hydrogen peroxide as a by-product. These structures are involved
in plant processes such as photorespiration.
- Plasmodesmata - pores or channels between plant cell walls
that allow molecules and communication signals to pass between
individual plant cells.
- Ribosomes - consisting of RNA and proteins, ribosomes are responsible for protein assembly.
- Vacuole - structure in a plant cell that provides support
and participates in a variety of cellular functions including storage,
detoxification, protection, and growth. When a plant cell matures, it
typically contains one large liquid-filled vacuole.
Plant Cell Types
As a plant matures, its cells become specialized in order to
perform certain functions necessary for survival. Some plant cells
synthesize and store organic products, while others help to transport
nutrients throughout the plant. Some examples of specialized
plant cell types
include:
- Parenchyma Cells - although not highly specialized, these cells synthesize and store organic products in the plant.
- Collenchyma Cells - help to support plants while not
restraining growth due to their lack of secondary walls and the absence
of a hardening agent in their primary walls.
- Sclerenchyma Cells - provide a support function in plants, but unlike collenchyma cells, they have a hardening agent and are much more rigid.
Plant cells are grouped together into various tissues. These
tissues can be simple, consisting of a single cell type, or complex,
consisting of more than one cell type. Above and beyond tissues, plants
also have a higher level of structure called
plant tissue systems
. There are three types of tissue systems: dermal tissue, vascular tissue, and ground tissue systems.
