Structure of plant cell

Introduction

Plants have an organized network of cells and tissues that help in carrying out many life processes. Most of the plants are made up of eukaryotic cells enclosing a unique green coloured structure-chlorophyll. Chlorophylls along with other plant organelles help in the photosynthesis. Plants belong to the kingdom Plantae - a unique kingdom possessing variable characteristic features. The cellular components that are exclusive only to plant cells are the cellulose, pectin, hemicelluloses and typical plastids. Plants have a  large vacuole help in maintaining the turgor pressure. Unlike animals, plants are stationary hence they lack motile elements such as flagella, however, few plants do have flagella. Plant leaf directly help in photosynthesis.

 

Cross section of leaf representing different cells

 

 Characteristics of plant cells

  1. Plant cells have protoplasts.

  2. They have a cell wall to protect them from external threat.

  3. They have a large vacuole than the mammalian cells. Vacuoles are the water-filled cavities enclosed by a membrane, tonoplasts. 

  4. Plants are autotrophic as they are capable of synthesizing their own food.

  5. Many plant cells contain a large central vacuole.

  6. Plant cells contain plastids. Plastids are the prominent type of chloroplasts enclosing the green-coloured pigments within -chlorophyll. Plastids can be  Amyloplasts help in the storage of starch,  elaioplasts are designed to store fat, and the chromoplasts participate in the production and storage of plant pigments.

 

Types of plant cells and tissues

Depending upon whether they are found in the roots, stems, leaves, flowers, or reproductive structures plant body cells are divided into parenchymal cells, Collenchyma cells, Scerenchymal cells, xylem, phloem and epidermis.  Let us look at each one in detail.

1. Parenchymal cells:

Parenchyma cells take part in storage of food material. They also support the process of photosynthesis through mesophyll cells, phloem, and xylem. The phloem and xylem act as a vascular channel assisting in material transport. Some of the parenchyma cells regulate the gas exchange because of their easy permeability.

2. Collenchyma cells:

Collenchyma cells looks like a slender and long. They have irregularly placed thick cell walls that provide structural support to leaves. Their thick cell walls are made up of cellulose and pectin often found under the epidermis.

3. Sclerenchyma cells:

Sclerenchyma cells are divided into sclereids and fibres as shown in the image. They have thick, lignified secondary walls found beneath the primary cell wall. As the secondary walls get harden, they do not permit the fluids or foreign material to enter through. Since the cells are rigid and non-stretchable, they found in the bark or mature stems where the growth is already seized.

 

Parenchyma. Colenchyma and Sclerenchyma

Xylem and phloem tissues

4. Xylem:

Xylem is a complex vascular tissue composed of water-conducting Tracheids along with fibres and parenchyma cells. They look like elongated cells with lignified secondary cell walls meant for the conduction of water. Xylem transport water and dissolved minerals from the roots to the rest of the plant. They also partly assist in the physical support

5. Phloem:

Phloem is otherwise known as the bast. Phloem tissues help in transporting the food synthesized in the leaves to the rest of the plant. Phloem have specialized cells; sieve tubes, companion cells, phloem fibres, and phloem parenchyma cells. 

6. Epidermis:

Epi means outer, so the epidermis is the outermost cell layer of the primary plant body. Epithelial cells found in on the epidermis protects the plant from harsh environmental conditions. Epidermal cells are tightly linked to each other forming a flat surface. Epidermal cells also help in providing the mechanical strength and protection necessary for the plant. Some of the plant cells contain cutin; help in the formation of the cuticle. Cuticles are protective, hydrophobic, waxy coverings produced by the epidermal cells of leaves, shoots and some of the aerial plant organs. Cuticles play a vital role to minimize water loss.

 

Microscopic anatomy of plant cell:

STOMAL CELLS

 

1. Cell Wall and cell membrane

The cell wall gives a framework and structural support to the cell.  Plant`s cell wall is a rigid layer containing the cellulose, lignin, pectin, glycoproteins, and hemicellulose. The cellular organization of plant cells are so made that they help in the photosynthesis when exposed to sunlight. Plasma membrane is found beneath the cell wall, as it has a thin layer of protein and fat, they assist in the selective permeability (allows only necessary material in and out) by creating a barrier to the toxins from outside.

2. Nucleus

Almost all the plant cells contain a nucleus. Nucleus help to store the genetic material- DNA. It is surrounded by the nuclear envelope within which a ground substance is present. The microelements floating across the ground substance is known as nucleoplasm. Nucleolus helps in the cell’s protein synthesis. DNA along with other nuclear elements help in growth, intermediary metabolism, protein synthesis, and cell division. The nuclear membrane has a perforated structure called nucleopore. Nucleopore has holes that allow proteins and nucleic acids to pass through.

3. Plastids

Plastids are membrane-bound organelles containing DNA. They play a major role in the storage of starch produced during photosynthesis. Plastids also synthesize many molecules that act as the building blocks of the cell. Plastids are further divided into Leucoplasts, Chloroplasts, and Chromoplasts. Leucoplasts are found in non-photosynthetic tissues of plants that assist in the storage of protein, lipid, and starch. Chloroplasts are disc-shaped and elongated organelle containing phospholipid membranes. They have a pore-like structure called the stroma. Each chloroplast contains the pigment, chlorophyll (green coloured) necessary for the process of photosynthesis. The chlorophyll exposed to sunlight will absorb the light energy from the sun and uses it for food production. During the process, carbon dioxide and water are being used to produce starch and oxygen. Chromoplasts are heterogeneous, coloured plastids responsible for pigment synthesis. The chromoplasts contains a range of coloured pigments; red, orange and yellow colour as we can see fruits and flowers.

4. Golgi apparatus

 It is the distribution and transportation department of the plant cell that  help in moving the necessary chemical substances. Golgi complex assists in modifying the proteins and fats present in the endoplasmic reticulum and prepares them to export them outside of the cell.

5. Ribosomes

Ribosomes are the tiny membrane-bound organelles encompassing RNA. Ribosomes assist in the protein synthesis therefore they are the protein factories of the cell.

6. Mitochondria

It is the powerhouse of cells enclosed within the double membrane. They provide energy by breaking down carbohydrates and sugar molecules, hence they are also referred to as the “Powerhouse of the cell.

 

Plant cell mitochondria

 

7. Lysosomes

 Lysosomes are called the suicidal bags as they perform cellular waste disposal function by digesting all the worn-out organelles, excessive food particles and foreign bodies found inside the cell.

 

Are you looking for a private tutor for CBSE, ICSE, IGCSE, IB, NIOS  syllabus? You have privilege to choose the hand-picked, qualified, certified home tutors from Innoclazz Academy. Book a free demo here to choose the best home tutors  from a network of 10,000 tutors . We provide best home tutors in Bangalore, Mumbai, Chennai, Pune, and Hyderabad.

Related topics

1             

Structure and functions of cells      

2

Tissues in our body

3

Cell cycle and cell division

4

Epithelial tissues
5

Adipose tissues

 

 

Questions

  1. What are chlorophylls and where do they found ?

  2. Which organelle help in maintaining the turgor pressure in a plant?

  3. Describe the  Characteristics of plant cells

  4. Mention the different cell-types present in the plants

  5. Briefly explain the structure of plant cell with the help of a diagram.

  6. What are Chromoplasts and leucoplasts? Explain their roles.

 

Are you looking for a private tutor for CBSE, ICSE, IGCSE, IB, NIOS  syllabus? You have privilege to choose the hand-picked, qualified, certified home tutors from Innoclazz Academy. Book a free demo here to choose the best home tutors  from a network of 10,000 tutors . We provide best home tutors in Bangalore, Mumbai, Chennai, Pune, and Hyderabad.

 

 



img-1


img-1


img-1

Course List