Plant CellPlant 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 OrganellesThe 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.
- Chloroplasts - 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 TypesAs 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.