A cell is defined as a fundamental unit that is vital for all life processes. A eukaryotic cell is a supermolecular structure comprising assemblies of cell organelles. Typically, each organelle has a specific function.
The cell structure of the plant is a structural and functional unit that carries specialised functions. They have a true nucleus along with organelles to aid in those functions. The distinctive aspect that differentiates the cells of a plant from an animal is that the former has a cell wall. Also, the vacuoles of plants are larger and centrally positioned.
Let’s have a detailed look at the organelles in the cellular unit of a plant.
The Cell Organelles
The organelles of a plant and animal cell are almost the same but show distinction in their functions. The plants also have plastids (in the form of chloroplasts), which help in the conversion of light energy into chemical energy. The mitochondrion is involved in the generation of ATP, and the endoplasmic reticulum is involved in protein synthesis.
Cell Wall
The cell wall constituents of the plant are the most abundant molecules on earth with diverse functions. The constituents are cellulose, hemicellulose, lignin, pectins and glycoproteins. It maintains the shape, provides protection, controls cell expansion, transports molecules and also functions in signalling processes.
Cell Membrane
This membrane structure is present between the cell wall and the cytoplasm. It is a semipermeable membrane composed of fats and proteins. It contains the cell organelles and plays a vital role in cell communication. Along with the cell wall, they form a boundary that acts as a barrier to the external environment. They aid in the entry of hormones, sugars and other molecules through the semipermeable membrane.
Nucleus
The nucleus is a vital structure that stores genetic information and is found only in eukaryotic cells. It helps in coordinating activities like cell division, protein synthesis, growth and also the intermediary metabolic processes. The primary role of the nucleus is to carry genes (DNA) that contain hereditary information.
Golgi
The Golgi apparatus in most vertebrates appears like a fibrous network. Whereas in plants and invertebrates, it appears as separate elements. It has a role in cell wall synthesis, protein sorting and also in protein glycosylation. It is central in distributing the synthesised macromolecules to different cellular parts.
Ribosomes
They comprise proteins and RNA and are found in the cellular cytosol. They are also called the protein factories as they are the major site for protein synthesis.
Endoplasmic Reticulum
They play a vital role in protein folding. Some regions of the endoplasmic reticulum lack ribosomes and appear smooth, while some have ribosomes attached to their surface and have a rough appearance.
Mitochondria
They disintegrate sugar and carbohydrates to generate energy in the form of ATPs.
Plastids
Plastids (chloroplast) contain green pigment (chlorophyll) that helps in the conversion of light energy into chemical energy. It is the notable plastid seen in most green plants. The other plastids include amyloplast, chromoplast, etc. Leucoplast is also a type of plastid seen in non-photosynthetic tissues.
Vacuole
A vacuole is a large storage organelle seen in plants. It is usually centrally positioned near the nucleus. It helps in maintaining the cell’s turgor pressure and also controls the movement of substances between the sap and the cytosol. The water-filled vacuole is often surrounded by a membrane called tonoplast. These were some of the organelles present in the cell structure of a plant. The plant cells are grouped into four types based on their specialised functions. They are parenchyma, chlorenchyma, collenchyma and sclerenchyma. The growing cells in the shoot and root meristems are the parenchyma. Sclerenchyma and collenchyma are thickened rigid cells that provide support to the plant. The chlorenchyma has chloroplast and lacks cell wall thickening. They are seen in young shoots and leaves.
Thus, the cellular unit of plants performs all the vital tasks needed for growth and functioning.
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