Plant Cell – Definition, Diagram, Structure, & Functions

A plant cell is a fundamental unit of a Plant’s structure. A plant cell is a eukaryotic cell, i.e., it has a defined nucleus enclosed within a membrane. Plant cells and animal cells difference occurs as they possess unique features that allow them to carry out essential functions.

Plant cell structure consists of a freely permeable cell wall. In this article, we will discuss plant cell parts and functions, its diagram and more in detail.

What is a Plant Cell?

Plant cells are one type of eukaryotic cell. Plant and animal cell contains the nucleus. The presence of a cell wall outside the cell membrane is one of the distinguishing characteristics of a plant cell. Plant cells also have different organelles with specific functions. The cell wall surrounds the plant cell membrane and the cell wall also provides shape to the cell. Plant cells have different components with specific functions.

Plant Cell Diagram

Plant cells are rectangular in shape and larger in size compared to animal cells. Given below is labeled diagram of plant cell.

Plant Cell Structure

The structure of a plant cell is made up of several parts known as cell organelles that serve the cell’s various needs for survival. Among these organelles are:

Cell Wall

The polysaccharides cellulose, pectin, and hemicellulose make up this hard layer known as cell wall. The cell wall is present outside the cell membrane in plant cells. Additionally, it contains polymers like lignin, cutin, and suberin as well as glycoproteins. The main purpose of the cell wall is protection and support of the cell from the external environments. The plant cell wall also helps provide the cell form and structure while defending it from mechanical stress.

Cell Membrane

The plant cell consists of a semi-permeable membrane within cell wall. A thin coating of protein and fat makes up its structure. The cell membrane is crucial in controlling how certain molecules enter and leave the cell. For instance, the cell membrane transports nutrition and vital minerals while preventing the entry of contaminants.

Nucleus

The nucleus is present in every eukaryotic cell, a structure that is membrane-bound. A nucleus’s essential function is to store the DNA or genetic material needed for cell division, metabolism, and growth. Nucleus is further divided into:

• Nucleolus: It creates the ribosomes and protein-producing components of cells.
• Nucleopore: Nucleopores, which are gaps in the nuclear membrane that allow proteins and nucleic acids to flow through, are present.

Plastids

Plastids are DNA-containing membrane-bound organelles of plant cell. They help in photosynthesis and store starch. Additionally, it is employed in the synthesis of several compounds, which serve as cellular building blocks.

Following is a list of some important plastid kinds and their roles:

Leucoplasts

They are located in plants’ non-photosynthetic tissue. They are employed for carbohydrate, fat, and protein storage.

Chloroplasts

It is an extended organelle with a phospholipid membrane surrounding it. The fluid contained within the disc-shaped chloroplast, known as the stroma, contains circular DNA. Chlorophyll, a pigment with green color needed for photosynthesis, is found in every chloroplast. The sun’s light energy is captured by chlorophyll, which is then used to convert water and carbon dioxide into glucose.

Chromoplasts

They are a type of colored, heterogeneous plastid that produces and stores pigment in plant cells. Red, orange, and yellow pigments found in chromoplasts give all ripe fruits and flowers their color.

Central Vacuole

In an adult plant cell, vacuoles take up around 30% to even 90% of the total volume. A membrane called the tonoplast encircles the core vacuole. Aside from storage, the central vacuole’s essential job is to maintain turgor pressure on the cell wall. Cell sap fills the central vacuole of the body. Salts, enzymes, and other compounds are mixed in with it.

Golgi Apparatus

Golgi Apparatus are present in all eukaryotic cells and are responsible for dispersing synthesized macromolecules to different cell regions. The Golgi body is made up of five to eight cisternae, or cup-shaped series of compartments. The Golgi apparatus is made up of layered pouches that are flattened and disc-shaped.

Ribosomes

They are the tiniest membrane-bound organelles of plant cell that contain both protein and RNA. They are also known as the cell’s protein factories since they are the sites of protein synthesis. Both prokaryotic and eukaryotic cells contain ribosomes, which are specialized cell organelles. Ribosomes are essential for the synthesis of proteins in every living cell.

Mitochondria

All plant cells have these double-membraned organelles in their cytoplasm. Mitochondria produce energy via breakdown of sugar and carbohydrate molecules into the energy rich molecule i.e., ATP, and known as the “Powerhouse of the Cell.” They play crucial role in the breakdown of nutrients and the production of molecules that are high in energy for the plant cell

Centrosomes

These are the plant cell organelles that are responsible for the synthesis of microtubules and is also useful in the process of cell division by forming the mitotic spindle. They are composed of the centrioles that was first discovered in animal cells.

Endoplasmic Reticulum

These are the cell organelles that are formed by by a complex network of membranous tubules that are located in the cell cytoplasm. The ER is of two types; rough endoplasmic reticulum, and soft endoplasmic reticulum. The RER is embedded with ribosomes that are responsible for the protein synthesis. The SER are responsible for lipid synthesis and metabolism.

Peroxisomes

These are the plant cell organelles that have single membrane and small structure similar to lysosomes. They also contains hydrolytic enzymes that are used to hydrolysed fatty acids and other molecules. They also help in the detoxification of the cell.

Types of Plant Cell

A mature and higher plant develops specialized cells that carry out specific crucial functions that are necessary for their survival. A small number of plant cells are responsible for transporting nutrients and water, while others are responsible for storing food. Included among the specialized plant cells are parenchyma, sclerenchyma, collenchyma, xylem, and phloem cells. Here are a few examples of the various plant cell types:

• Collenchyma Cells: When a plant’s growth is constrained due to a lack of a hardening agent in the major walls, these hard or rigid cells perform a crucial role in supporting the plant.
• Sclerenchyma Cells: Due to the presence of a hardening agent, these cells are more rigid than collenchyma cells. These cells are typically present in all plant roots and serve mostly to support the plants.
• Parenchyma Cells: In all plants cells, parenchyma cells perform a crucial role. They play a role in the development of leaves. Additionally, they have a role in the metabolism of cells, food generation, storage of organic materials, and gas exchange. Because they are thinner than other cells, these cells are usually more flexible.
• Xylem Cells: In vascular plants, the transport cells are called xylem cells. They help in moving minerals and water from the roots of the plant to the leaves and other regions.
• Phloem Cells: Other transport cells in vascular plants are called phloem cells. They move the food that the leaves have prepared to other plant components.

Function of Plant Cell

Major functions of plant cells are:

• The primary function of the plant cell is photosynthesis. Photosynthesis is the process by which sun’s light energy is converted into chemical energy. It takes place in the chloroplast of plant cells.
• Some plant cells also transport water and minerals from roots and leaves to the different parts of the plant.
• They perform cellular respiration to synthesize energy.
• They store nutrients and water in their vacuoles.
• They perform the synthesis of organic compounds like carbohydrates, proteins, lipids, etc.
• They perform cell to cell communication to share chemical signalling.
• They provide support and protection by the help of sclerenchyma and collenchyma cells.

Plant Cell and Animal Cell Difference

The difference between plant cell and animal cell is given below:

Feature	Plant Cells	Animal Cells
Cell Wall	The cell wall is present in plant cells and is made up of cellulose. The cell wall is the outermost layer of plant cells.	it is absent in the animal cell.
Shape	They have a definite and rigid shape which means they usually exist in rectangular or cubical shapes.	They exist in round and irregular shapes.
Chloroplast	Chloroplasts are present in plant cells that make their own food.	Chloroplast absent in animal cell
Mitochondria	It is present in a small number in plant cells. Plants cells generally have approximately 200-600 mitochondria per cell.	It is present in a large number compared to plant cells, Animal cells generally have approximately  2000 per cell.
Nucleus	It is present and controls the functioning of cells.	It is present and stores the cell’s DNA,
Plasma Membrane	PM is present and it is surrounded by cell walls in the plant cell.	PM is present in animal cells. it provides protection for the cell.
Vacuoles	Vacuoles are few large or single and centrally positioned and provide structural support. One huge vacuole.	Vacuoles are commonly small in size and sometimes they are absent.
Mode of Nutrition	It is the present mainly autotrophic mode of nutrition which means they synthesize their own nutrients such as amino acids, vitamins coenzymes that are required by the plant.	The mode of nutrition is heterotrophic. which means they cannot synthesize their own nutrients.
Golgi apparatus	A Single highly difficult and prominent Golgi apparatus is present.	The mode of nutrition is heterotrophic. which means they cannot synthesize their own nutrients.

Conclusion – Plant Cell – Definition, Diagram, Structure, & Functions

In conclusion, the plant cell serves as the fundamental building block of plant structure, featuring a eukaryotic composition with unique organelles such as the nucleus, cell wall, chloroplasts, and vacuoles. These specialized components enable crucial functions like photosynthesis, nutrient transportation, energy production, and structural support, contributing to the plant’s growth, metabolism, and survival in its environment.

FAQs on Plant Cell

Who Discovered Plant Cell?

Robert Hooke discovered plant cells in 1665. He discovers plant cells by observing the cell walls within cork tissue through a microscope.

What are the Different Types of Plant Cells?

The different types of plant cells are collenchyma, sclerenchyma, parenchyma, xylem and phloem.

What are 7 Types of Plant Cells?

The 7 common types of plant cells are the parenchyma cells, sclerenchyma cells, collenchyma cells, xylem cells, phloem cells, meristematic cells, and epidermal cells.

What Shape is a Plant Cell?

The shape of plant cell is rectangular. This is due to the presence of the rigid cell wall and the pressure exerted by the vacuoles on the cell membrane.

Why are Plant Cells Green?

The plant cells are green due to the presence of green colored chlorophyll pigments that are located inside the chloroplast organelle of the plant cell.

What is the Composition of a Plant Cell Wall?

The plant cell wall is primarily composed of cellulose, hemicellulose, and pectin, providing structural support and protection to the cell. Additionally, it contains other substances like lignin, cutin, and suberin, contributing to its rigidity and impermeability.