Structure and functions of plant cell

Introduction to plant cells

A cell forms the basis of life since it is a structural and functional unit of life irrespective of whether it belongs to a plant or animal. Animals, fungi, and protists are made up of eukaryotic cells, while bacteria and archaea are made up of the primitive prokaryotic cells. Plant cells are the typical eukaryotic type of cells with a distinct nucleus that encloses the genetic material at the centre. They possess many organelles spread across the cytoplasm. Plant cell differs in many ways when compared to the animal cells. One of the principal difference is that they have green pigments inside the chlorophyll that help in synthesizing their own food which we don't see it in the animal cells. Additionally, plant cells have a rigid cell wall all along with a large central vacuole which is absent in animals. Furthermore, cells in a plant may slightly vary depending upon whether they are found in roots, stems, leaves etc.  Plant cells are photoautotrophic as thy utilize sunlight to produce energy. However, rarely some heterotrophic plants are found ( they trap insects for their food). 

 

 

 

Parts of plant Cell

A plant cell has many parts with each part performing specialized function and the internal structures are called cell organelles.

 

 

Chloroplasts

Chloroplasts are exclusively found in the cells of plants and algae. They are the green parts that help in carrying out photosynthesis where water, carbon dioxide, and light energy are used to produce food. They are oval-shaped discs having two membranes. The outer membrane forms the external surface of the chloroplast, and an inner membrane lies just beneath the outer. The space between the two layers is a thin intermembrane space measuring 10-20 nanometers wide. Stroma along with chloroplasts, thylakoids, chlorophyll and carotenoids are found on the outer layer. These organelles aid in capturing light energy while the chromoplasts are heterogeneous, coloured plastids participates in the production and storage of pigments. They have red, orange and yellow coloured pigments.

 

Vacuoles

Plant cells have a centrally placed large vacuoles when compared to other organisms. A vacuole is a  spherical membranous sac containing fluids, ions, and many other molecules. A large vacuole can roughly occupy anywhere from 30-80 percent of the cell, however it differs. Vacuole helps to maintain the turgidity or turgor pressure of a cell with the help of its fluid . Consequently,  due to the pressure,  the  contents  in the cell are pushed  against the cell wall. Turgidity is essential for the plants to survive as the steep fall in the turgidity results in the dryness of the cell but the most healthy environment for plant cell is when it has excess of hypotonic solution. This will help the highly concentrated external fluid to rush into the cell through osmosis. A well-hydrated cell is an indication of a productive plant.

 

 

The cell wall

Having said that the plants are unique because they have a strong cell wall which the animals lack. The cell wall in a plant is a very dense layer made up of cellulose, along with hemicellulose, pectin, and lignins. These elements ensure that the cell is protected from external environmental factors. Plant’s cell wall differentiates itself from the cell wall of fungi as they lack chitin and peptidoglycans. The cell wall is formed with the help of microtubules and it has  3 important layers,; primary, secondary and middle lamella

 

 

Cell membrane

The cell membrane is a semipermeable membrane that lies close to the cell wall. It is made up of lipid bilayer along with the thin layer of proteins. The cell membrane is an essential component that regulates the movement of materials across the membrane.  The membrane also guards the cell against toxins , while allowing only the essential nutrients and  minerals in and out of it.

 

Nucleus

Since plants contain eukaryotic cells, the nucleus has a membrane within which  DNA is located. iDNA is a genetic material necessary for  the cell division, metabolism, and growth. The nucleolus found inside the nucleus assist in protein synthesis. The nuclear membrane of a plant cell has a perforated nucleopore . Nucleopores  allows proteins and nucleic acids to pass through.

 

Golgi apparatus

They assis in the distribution of  already synthesized macromolecules to various parts of the cell.

 

Ribosomes

Ribosomes are otherwise known as the protein factories of the cell as they provide a physical space necessary for protein synthesis. They are membrane-bound organelles containing RNA.

 

Mitochondria 

Mitochondria are the powerhouse of a cell as they synthesize ATP through cellular respiration. Mitochondrion utilizes the nutrients produced by the chloroplasts to provide energy for all the cellular processes such as metabolism, transportation of mineral, absorption of nutrients through roots etc.

 

Lysosomes

Lysosomes are called the suicidal bags of the cell. They contain digestive enzymes that performs  cellular waste disposal by digesting the worn-out organelles from time to time. This helps the cells to be healthy and balanced.

 

Cytoplasm

The liquid dispersed within the cytoplasm is called the cytosol that is made of water ions like potassium, proteins, and small molecules. Furthermore, cytoskeleton is a network of filaments and tubules scattered across the cytoplasm of the cell. Cytoskeletons provides cell ,the  necessary shape, strength, and a framework. It assists in anchoring all the organelles within the cell, and has a role in cell signaling.

 

 

Types of cells in plants

Plant cells are of 5 different types with each one performing different functions, they are:

  1. Parenchyma cells: They are found in leaves, and they form the major proportion of plant cells. They carry out photosynthesis and cellular respiration, and some of the metabolic processes. In addition, they store substances such as starches and proteins.

  2. Collenchyma cells: These are elongated, thick cells capable of growing faster to change the shape of the plant. They provide support to growing parts of plants.

  3. Sclerenchyma cells: These are generally hard and dead cells with very thick cell walls.

  4. Phloem cells: They are primarily involved in the transportation of nutrients produced during photosynthesis.

  5. Xylem cells: They aid in transporting water and a few water-soluble nutrients. They first absorb the water and nutrients from roots followed by that, they create a long channel to transport the necessary nutrients and water.  

 

 

Functions of plant cell

Photosynthesis, is the major role that plants perform as most of the plants are chemoautotrophic. They synthesize the food required for all other organisms either directly or indirectly. Therefore, in an ecosystem, every living organisms rely upon the plants for their food.

 

 



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