Plant Cell-Definition, Structure, Parts, Functions, Labeled Diagram

Definition of plant cell

Plant cell is a eukaryotic cell found in green plants, which are photosynthetic eukaryotes that belong to the kingdom Plantae and have a membrane-bound nucleus. Plant cell include a variety of membrane-bound organelles that perform various functions to maintain the health of the plant cell.

Structure of Plant cell

Typically, plant cells are bigger than animal cells of equivalent size and structure. Typically, they have a cubic or rectangular shape. The cell wall, vacuoles, and plastids, such as Chloroplast, are structural organelles present in plant cells which are not seen in animal cells. Cilia flagella, lysosomes, and centrioles are all features present in animal cells that are not seen in plant cells.

Figure: Labeled diagram of a plant cell, created with biorender.com

The plant cell is comprised of cellulose, hemicellulose, and pectin, as well as plastids, which are essential for photosynthesis and starch storage, and enormous vacuoles that control cell turgor pressure. They also feature a one-of-a-kind cell division mechanism in which a phragmoplast (a structure composed of microtubules, microfilaments, and the endoplasmic reticulum) during cytokinesis, the division of daughter cells occurs.

The bulk of these organelles are comparable to those of animal cells and perform the same functions. Organelles are responsible for a range of functions, including the production of hormones and enzymes and the delivery of energy to plant cells.

Plant cells include DNA that aids in the formation of new cells, allowing the plant to grow faster. The nucleus, an encapsulated membrane structure in the cell’s core, contains the DNA. The plant cell also features a number of cell organelle structures that conduct a range of functions in order to keep cellular metabolisms, growth, and development running smoothly.

Free Plant Cell Worksheet

List of Plant cell organelles

  1. Cell Wall
  2. Cytoskeleton
  3. Cell (Plasma) membrane
  4. Plasmodesmata
  5. The cytoplasm
  6. Plastids
  7. Plant Vacuoles
  8. Mitochondria
  9. Endoplasmic reticulum (ER)
  10. Ribosomes
  11. Storage granules
  12. Golgi bodies
  13. Nucleus
  14. Peroxisomes

Definition of plant cell wall

It is the plant’s tough outer covering cell that protects the plant cell while also giving it form.

Structure of plant cell wall

  • It is a particular matrix that covers the surface of plant cells. Every plant cell comprises a cell wall layer, which is a distinguishing characteristic between plant and animal cells.
  • The cell wall consists of a central lamella, a primary cell wall, and sometimes a secondary cell wall.
  • The intermediate lamella functions as a reinforcing layer between the major walls of adjoining cells.
  • Underlying the dividing and developing cells is cellulose, which forms the main wall. When compared to cells that have attained full maturity, the main wall is much thinner and less stiff. The thin cell wall permits the cell to grow.
  • Some plants remove the main wall when cell development is complete, while the majority thicken it or form a secondary wall, which is a stiff layer with a different pattern.
  • The secondary wall provides the plant cell with permanent rigid mechanical support, similar to that seen in wood.
  • In contrast to the permanent stiffness and load-bearing capacity of thick secondary walls,

The function of the plant cell wall

The primary function of the cell wall is a mechanical and structural one that serves the plant cell very well. These are some of the functions:

  1. The secondary wall layer provides mechanical protection to the cell while also sheltering it from the chemically hostile surroundings.
  2. It is semipermeable, enabling substances like water, molecular nutrients, as well as minerals, to enter and exit.
  3. It also acts as a hard building block for the plant, helping it develop the stem and leaves, among other features.
  4. It also served as a storage location for certain components, including regulating compounds that detect infections in plants and prevent damaged tissue from developing.
  5. When the cell vacuoles are filled with water, the thin primary walls operate like structural and supporting functional layers, exerting turgor pressure on the cell wall, thus maintaining the rigidity of the plant and preventing water loss and wilting.

Despite their diverse compositions and topologies, cellulose fibres are the essential building component of both the main and secondary walls. Cellulose is a polysaccharide matrix that imparts tensile strength to the cells. The extremely dense matrix of water and glycoproteins provides this strength.

Definition of the plant cytoskeleton

This is a microtubule and filament network that is responsible for preserving the shape of the plant cell, as well as providing support for the cytoplasm and maintaining its structural structure. These filaments and tubules ordinarily extend throughout the cytoplasm of the cell. It is also engaged in the movement of cellular molecules, cell division, and cell signalling activities, in addition to providing support and sustaining the cell and its cytoplasm.

Structure of the plant cytoskeleton

The cytoskeleton is an essential component of eukaryotic cell structure since it defines the cell’s support system, maintenance components, and transport functions. These functions are defined by the cytoskeleton, which consists of three filaments: actin filaments (microfilaments), microtubules, and intermediate filaments.

  • Microfilaments, also known as actin filaments, consist of parallel-running fibres woven into a mesh. Hence the name, actin filaments consist of thin strands of actin proteins. With a thickness of 7 nanometers, they are the cytoskeleton’s thinnest filaments.
  • Intermediate filaments, which are located between actin filaments and microtubules, have a diameter of roughly 8–12 nm. Its role in plant cells isn’t well known.
  • Microtubules are hollow tubulin tubes with a diameter of 23 nanometers. When compared to the other two strands, they are the biggest.

Functions of the plant cytoskeleton


  • They are primarily responsible for the cytoplasmic division of the cell, which results in the formation of two daughter cells, a process known as cytokinesis.
  • They are also involved in cytoplasmic streaming, which involves cytosol flowing throughout the cell and carrying nutrients and cell organelles.

Intermediate filaments

  • Intermediate filaments in plant cells play a role in maintaining cell shape, structural support, and intracellular tension, although their relevance is uncertain.


  • In contrast to animal cells, which require microtubules for cell division, plant cells use microtubules to move materials inside the vell and to construct the cell wall.

Other functions of the cytoskeleton in plants include:

  • The cytoplasm is responsible for giving the plant cell its structure, maintaining its shape, and moving particular cell organelles, chemicals, and nutrients throughout the cell cytoplasm.
  • It’s also involved in cell division during mitosis.
  • In conclusion, the cytoskeleton is the framework that supports and defines the cell structure. It sustains cell structure, offers structural support, and specifies cell structure.

Structure of the plant cell (plasma) membrane

  • This is a bilipid membrane with a semi-permeability component. This consists of protein subunits and carbs.
  • It encircles the cytoplasm of the cell, thereby encapsulating its contents.

The membrane of the plant cell (plasma) functions

  • In plant cells, the cell membrane divides the cytoplasm from the cell wall.
  • It has selective permeability, meaning it regulates the substances that enter and leave the cell.
  • It also provides the cell with support and stability and shields it from external damage.
  • It contains embedded proteins that are coupled with lipids and carbohydrates and are used to transport biological molecules throughout the membrane.

Definition of Plasmodesmata of the plant cell

These are tiny passageways that let plants communicate and move materials between cells. They facilitate intracellular transport of cellular nutrients, water, minerals, and other substances by connecting the cellular plant spaces. They also enable biological molecules to communicate with one another. Plasmodesmata are divided into two categories.

  • During cell division, primary plasmodesmata arise.
  • Secondary plasmodesmata are plasmodesmata that occur between mature plant cells.

When a portion of the endoplasmic reticulum gets trapped in the middle lamella during the processing of the new cell wall during cell division, primary plasmodesmata occur. They develop a link between each other as they form, and at the connecting location, they generate thin gaps on the walls known as pits. Secondary plasmodesmata are plasmodesmata that are inserted between the cell wall and the cell membrane of mature cells. These may be present in both plant and algal cells and have evolved separately. The callose polymer is generated when cell cytokinesis regulates the configuration of plasmodesmata.

Structure of plasmodesmata of plant cells

Plasmodesmata are 50–60 nanometers in diameter. The plasma membrane, cytoplasmic sleeve, and desmotubules are the three layers. The cell wall may be thickened by up to 90 nanometers by these layers.

  1. The plasma membrane is a prolonged continuation of the plasmalemma consisting of a phospholipid bilayer structure.
  2. Cytoplasmic sleeves are fluid-filled pockets surrounded by the plasmalemma, producing a cytosol pouch that never ends.
  3. Desmotubules are flat tubes that run between two neighbouring cells and originate from the endoplasmic reticulum.

Functions of the plasmodesmata

  • Transcript proteins, small pieces of RNA, mRNA, viral genomes, and viral particles are all transported from one cell to another. For example, the MP-30 proteins of the Tobacco mosaic virus connect to the viral genome and convey it from infected to uninfected cells through plasmodesmata. MP-30 is hypothesised to bind to the virus’s own genome and move it from infected to uninfected cells through plasmodesmata.
  • With the support of partner cells, they are employed to control the sieve tube cells.
  • They’re also employed by phloem cells to make nutrient delivery easier.

The cytoplasm of the Plant Cell

  • The majority of the cell organelles are housed in this gel-like matrix that lies just under the cell membrane.
  • Water, enzymes, salts, organelles, and different organic compounds make up the body.
  • It is not considered an organelle since it just acts as a physical medium for maintaining and hosting the majority of the cell’s complex internal organelles, as well as transporting and processing cell chemicals to keep the cell alive.
  • This is because some of these organelles possess their own distinct protective membranes; for example, the mitochondria and Golgi bodies contain at least two layers that provide many roles for the organelles.
  • The nucleus is not considered to be a component of the cytoplasm due to its double-layered structure, central location, and unique organelles and sub-organelles.
  • Plastids, Mitochondria, Central vacuoles, Endoplasmic reticulum, Golgi bodies, Storage granules, and Lysosomes are among the organelles found in the cytoplasm of the plant.

Plastids of plant cells

  • Plant and algal cells have specialised organelles known as plastids. They have a membrane that is double-layered.
  • They feature distinct colours that enhance their functions, particularly in the processing and storage of food. The colour of the plant is likewise determined by these pigments.
  • Plastids are a double-membrane organelle present in the cells of plants and algae that are responsible for food production and storage.
  • Plastids may discriminate between their forms and can proliferate quickly by binary fission, creating over 1000 plastid copies depending on the cell. Plastids are reduced to roughly 100 per mature cell in mature cells.
  • Plastids are derived from proplastids (undifferentiated plastids), which are present in the plant’s meristematic tissues.

Development of plastids

Plastids are enormous protein-DNA complexes that are connected to the cell’s inner membrane and are called plastid nucleoids. The nucleoids contain a minimum of 10 copies of plastid DNA. Proplastids are plastids that are undifferentiated and have just one nucleoid. These develop into plastids, which have additional nucleoids at the membrane’s borders that are attached to the inner envelope membrane.

The proplastid nucleoid undergoes modification throughout differentiation and development, altering its form and size and moving to a new place inside the organelle. The nucleoid proteins are involved in this remodelling pathway.

General functions of plastids

  • Because of the existence of chlorophyll pigment in chloroplasts, they are actively involved in photosynthesis and the creation of food for the plant.
  • They also store food in the form of starch.
  • They have the capacity to provide energy for the cell’s systems by synthesising fatty acids and terpenes.
  • Palmitic acid, a chloroplast-produced component, is needed to make the plant cuticle and waxy components.

Types of Plastids

Plastids are divided into groups depending on their functionality as well as the availability of certain pigments. They are as follows:

  • Chloroplasts: Chloroplastsare photosynthesis-related green plastids.
  • Chromoplasts:Plant pigments are synthesised and stored in chromoplasts, which are coloured plastids.
  • Gerontoplasts:Plants’ photosynthetic systems are dismantled by gerontoplasts as they age.
  • Leucoplasts:Leucoplasts are colourless plastids that are employed to make a terpene compound that protects plants. They have the ability to differentiate, resulting in the formation of specialised plastids that perform a range of activities. amyloplasts, elaioplasts, proteinoplasts, and tannosomes, for example.

Structure of the plant cell chloroplast

  • Both plant and algal cells have these organelles.
  • They have an oval shape to them.
  • They consist of two surface membranes, the outer as well as inner membranes, and two membranes in the thylakoid layer of the inner layer.
  • The outer membrane creates the chloroplast’s exterior coating, while the inner membrane lies underneath it.
  • The membranes are divided by a narrow membranous gap, and inside each membrane is an area known as the stroma. The stroma houses the chloroplasts.
  • The thylakoid layer is widely folded. It has large concentrations of chlorophyll and carotenoids, as well as the electron transport chain, commonly known as the light-harvesting complex, which is used during photosynthesis, giving it the appearance of a flattened disc.
  • Grana are stacks of thylakoids heaped on top of each other.

Functions of the plant cell chloroplast

  • The chloroplast is the site of photosynthesis, which provides plant cells with nutrition.
  • Chlorophyll is a green pigment found in chloroplasts that collects solar light during photosynthesis.
  • Photosynthesis is the conversion of water, carbon dioxide, and light energy into nutrients that plants can use.
  • The pigments chlorophyll and carotenoids are present in thylakoids, which gather light energy for photosynthesis.
  • Plants get their green hue from the chlorophyll pigment.

Chromoplast plastid of the plant cell

Chromoplast is a kind of chromosome.

  • Chromoplasts are the organelles that store and manufacture plant pigments.
  • They may be found in a wide range of plants of various ages.
  • They are generally created from the chloroplasts, which is the term given to a place in the plant where all of the pigments are stored and manufactured.

They contain carotenoid pigments, which allow for colour diversity in flowers and fruits. Pollinators are attracted to it because of its colour.

Structure of plant chromoplast

According to microscopic examination, there are at least four varieties of chromoplast:

  1. Granule-containing proteic stroma
  2. A granular amorphous pigment
  3. Crystals with protein and pigment
  4. Chromoplasts that have crystallised

However, the more specialised characteristic has been identified, and it has been classified into five types:

  1. Globular chromoplasts are globular chromoplasts that look like globules.
  2. Crystalline chromoplast with a crystalized appearance
  3. Fibrillar chromoplast is a kind of chromoplast that looks like fibres.
  4. A tubular chromoplast is a kind of chromoplast that appears like a tube.
  5. Membranous chromoplast

Some plants have distinct forms of chromoplasts, like mangoes, which contain globular chromoplasts; carrots, which have crystallised chromoplasts; and tomatoes, which contain mixed crystalline and membranous chromoplasts due to the carotenoids they collect.

Functions of the plant chromoplast

  1. They provide plant components including flowers, fruits, roots, and leaves with different hues. The transition from chloroplast to chromoplast causes the plant’s fruits to ripen.
  2. Plant pigments, such as yellow pigments for xanthophylls and orange pigments for carotenes, are synthesised and stored by them. The colour of the plant and its sections comes from this.
  3. The colours they generate attract pollinators; this facilitates the reproduction of plant seeds.
  4. Chromoplats in roots allow water-insoluble substances to accumulate, notably in tubers like carrots and potatoes.
  5. They play a role in the colour change of flowers, fruits, and leaves as plants age.

Gerontoplast plastids of the plant cell

  • The organelles responsible for cell ageing are plastids, which may be found in plant leaves. When the plants become older, they separate from the chloroplast and can no longer produce photosynthesis.
  • They look like unstacked chloroplasts with no thylakoid membrane and an aggregation of plastoglobuli, which are responsible for the cell’s energy production.
  • Gerontoplast’s principal role is to help in the ageing of plant parts by giving them a unique hue to indicate the absence of photosynthesis.

Leucoplast plastids of the plant cell

  • They are the plastids that lack coloration. They are found in non-photosynthetic plant parts, such as roots and seeds, since they lack chloroplast pigments.
  • They are smaller than chloroplasts, which have a variety of morphologies, some of which resemble ameboid shapes.
  • They are linked by a network of stromules in the roots and flower petals.
  • They may be adapted to store vast amounts of starch, lipids, or proteins, and are therefore called amyloplasts, elaioplasts, or proteinoplasts, depending on what they store.

The leucoplast’s primary role is to

  • Starch, lipids, and proteins are all stored here.
  • Amino acids and fatty acids are also converted using them.

Plant vacuoles definition

  • In comparison to animal cells, plant cells contain huge vacuoles.
  • The core vacuoles may be seen in the cytoplasmic layer of cells from a wide range of animals, although they are bigger in plant cells.

Structure of plant cell vacuoles

  • These are huge, fluid-filled vesicles found in a cell’s cytoplasm.
  • It makes up approximately 30% of the cell’s volume in fluid but may occupy up to 90% of the cell’s intracellular space.

Functions of the central vacuole

  • The central vacuoles are used to control cell size and sustain turgor pressure within plant cells, preventing plants from wilting and withering, particularly leaves.
  • The vacuoles account for the majority of the plant cell’s size while the cytoplasmic volume is constant.
  • The turgor pressure is maintained when the vacuoles are filled with water. When turgor pressure is absent, the plant loses water, causing the leaves and stems to wither.
  • Plant cells flourish in humid surroundings (hypotonic solutions), absorbing water from the environment by osmosis and retaining turgidity.
  • More than one sort of vacuole may exist in a plant cell. Certain specialised vacuoles, particularly those physically linked to lysosomes, contain the degradative enzymes required to break down macromolecules.
  • Vacuoles also store carbohydrates, organic salts, inorganic salts, proteins, cellular colours, and lipids, among other cellular nutrients. These components are kept in the cell until they are needed for cellular metabolism. Seed proteins and opium metabolites, for example, are stored in vacuoles.

Plant cell mitochondria definition

  • Mitochondria, commonly called chondriosomes, are the organelles of a cell that generate energy and are hence referred to as the cell’s “powerhouse.”
  • The mitochondria use oxygen to transform stored nutrients into energy in the form of (ATP)Adenosine TriPhosphate, making them the location for non-photosynthetic energy transduction.
  • A single plant cell has hundreds of mitochondria.
  • In addition, mitochondria may be discovered in large quantities inside the plant cell’s phloem pigment, and nearby cellular metabolic rates are high. This is to provide energy for many needed systems, such as food movement via sieve tubes.
  • Mitochondria migrate and alter shape as they carry out their functions. Photosynthesis is dependent on interactions with trapped light, cytosolic sugar levels, and endoplasmic reticulum-mediated interactions.
  • Mitochondria in animal cells lack the enzyme reduced nicotinamide adenine dinucleotide (NADH) dehyg=drogenase needed for the oxidation of exogenous NADH, but plant mitochondria possess this enzyme.
  • Numerous plant mitochondria are relatively cyanide-resistant, which is not the case with animal mitochondria. The fatty acid b-oxidation route, on the other hand, is found in animal mitochondria, while fatty acid oxidation enzymes are found in plant glyoxysomes.

Structure of plant mitochondria

  • Mitochondria in plant cells are very pleomorphic.
  • Mitochondria within green plants are discrete, spherical-oval organelles measuring between 0.2 and 1.5 m in diameter.
  • The mitochondrial matrix features a double-layered structure, consisting of a soft outer membrane and a complex inner membrane. The organelle matrix is encased by these membranes.
  • Complexes of lipid bilayers and a hydrophobic fatty acid chain compose the two layers. This class of phospholipids has a great affinity for fatty acid regions and is quite dynamic.
  • In the central bulk, they possess a mitochondrial gel matrix.
  • In addition to citrate synthetase, pyruvate oxidase, Isocitrate Dehydrogenase, Malate Dehydrogenase, and Malic Enzyme, mitochondria include all the enzymes for the Tricarboxylic cycle (TCA).

Functions of mitochondria in plants.

  • As the powerhouse of the cell, the mitochondria’s primary duty is to generate energy for the cell.
  • They possess a high metabolic rate since they provide power for an unidentified mechanism that delivers food. mostly sucrose, down the sieve tubes.
  • The potential energy in nutrients created by photosynthesis is used for cellular metabolism inside the mitochondria. For instance, the mitochondria create the energy required for the synthesis of new cell content, the generation of enzymes, and the movement of sugar molecules.
  • It is a reference to the Krebs cycle, also called the Tricarboxylic cycle (TCA). The TCA cycle transforms cellular nutrients into metabolites that are used by the mitochondria to produce energy. Since the membrane is folded into cristae, where the protein components of the Electron Transport Chain reside, these processes occur in the inner membrane. (ETC). This is the major energy generation mechanism of cells. ETC is the body’s primary source of ATP generation.

Plant cell endoplasmic reticulum (ER) definition

  • The ER is a network of folded membrane sacs contained inside the cytoplasm of the cell. It is a complex organelle, comprising a significant portion of the cytoplasm of the cell.
  • It is composed of the rough endoplasmic reticulum (whose surface membrane contains ribosomes) and the smooth endoplasmic reticulum (which lacks ribosomal attachment).
  • In eukaryotic cells, proteins, lipids, and chemical components are produced, digested, transported, and stored by the endoplasmic reticulum. The plant cell and other organelles, such as the vacuoles and apoplast, are known as organelles, employ these components (plasma membrane).
  • The ER’s interior space is called the lumen.
  • Connected to the nuclear coat, it offers a link between the nucleus and cytoplasm of the cell, as well as a link between both the cell and the plasmodesmata tubes that connect plant cells. It constitutes 10 percent of the cytosol’s overall volume.
  • In contrast, rough ER generally occurs as double membrane stacks containing ribosomes. On the basis of its uniform appearance, Most likely, rough ER comprises of parallel membrane layers. as opposed to the tubular sheets that define smooth ER.
  • These interconnected, elongated sacs are called cisternae or cisternal cells. ER cisternal cells are also referred to as luminal cells. The Rough ER and the Golgi complex are both composed of cisternal cells.

Structure of plant cell endoplasmic reticulum

  • This cytoplasmic organelle of a cell is composed of a thin network of flattened connected compartments (sacs) that connect the cytoplasm to the nucleus.
  • Within its membranes, there are membranous holes known as cristae spaces and membrane folding known as cristae.
  • According to their structure and function, Rough Endoplasmic Reticulum (ER) and Smooth Endoplasmic Reticulum (SER) are the two types of ER.

Functions of the endoplasmic reticulum

Functions of the Rough and smooth endoplasmic reticulum

  • Ribosomes cover the surface membrane of the rough endoplasmic reticulum, giving it a rough, bumpy appearance. The primary purpose of the Rough ER is to synthesise proteins, which are subsequently transported from the cell to the Golgi bodies, where they are transported to various developmental regions of the plant. Antibodies, hormones, and digestive enzymes are all made up of proteins, which are made up of amino acid sequences. The ribosomes connected to the rough ER are responsible for the assembly.
  • Some proteins are processed outside the cell, but they may also be transported to the Rough ER, where they are assembled into the proper shape and size for cell function, and sugar elements are conjugated to form a complete protein. These complexes are then distributed and transferred to the transitional ER, where they are packaged in cell vesicles and exported to different areas of the plant via the Golgi bodies.
  • The ER is smooth because there are no linked surface ribosomes. They seem to be emerging from the endoplasmic reticulum lumen. This organelle is responsible for synthesising, secreting, and storing lipids, as well as metabolising carbohydrates and producing new membranes. Numerous enzymes attached to its surface contribute to this.
  • When a plant has sufficient energy for photosynthesis but still has excess lipids generated by the cell, these lipids are stored in the smooth endoplasmic reticulum as triglycerides. When plant cells demand more energy, triglycerides are broken down to provide the necessary fuel.
  • To a lesser degree, the smooth endoplasmic reticulum has been linked to the formation of cellulose in the cell wall.

Other functions of the endoplasmic reticulum in the plant cell

  • Calcium is needed for plant cell growth and development, but it may also be generated in excess amounts, which can injure the plant cell by inducing cell death. As a result, the Endoplasmic reticulum has been connected to calcium oxalate crystal formation in order to regulate excess calcium. Crystal idioblasts, which are specialised cells in the endoplasmic reticulum, play a key role in both the conversion and storage of these crystals.
  • Plant sensors are also provided by the ER. Plants may respond to environmental stimuli such as light intensity, temperature, and air pressure by making quick movements. The ER acts as a mediator in such systems, allowing the plant to react appropriately. The presence of the cortex endoplasmic reticulum (Cortex cells) in the Venus flytrap plant, for example, causes the plant to react sensitively to touch.
  1. The sensory ER migrates and accumulates at the top and bottom of the cell during sensitivity, forcing them to be pressed together and producing a restriction. This causes stored calcium to be released, resulting in the sensation of touch.
  2. The plasmodesmata and the cortical ER are inextricably intertwined (a thin filament of cytoplasm that traverses the cell walls of neighbouring plant cells and facilitates communication between them). Plasmodesmata function as a communication pathway between cells, linking to motor cells and prompting the cells and plant to respond accordingly.

Plant cell ribosome definition

  • This organelle is in charge of the cell’s protein production.
  • It may be found in huge numbers in the cell cytoplasm, and a few of them, known as functional ribosomes, can also be found in the nucleus, mitochondria, and cell chloroplast.
  • It’s made up of cell proteins and ribosomal DNA (rDNA).
  • Translation is the process of ribosomes synthesising proteins with the help of messenger RNA, which transports nucleotides to the ribosomes.
  • The ribosomes then direct and translate the message, which is stored in the form of nucleotides in the mRNA.

Structure of ribosomes of the plant cell

  • Ribosomes have the same structure in all cells, but bacterial ribosomes are smaller. In the majority of eukaryotic cells, ribosomes are so large that they can only be measured in Svedberg units (S). The S unit measures the aggregation of large molecules into sediments during centrifugation. A high S value suggests a rapid sedimentation rate and, thus, a greater mass.
  • In the 1990s, eukaryotic cell sediment predominated, whereas prokaryotic cell sediment predominated in the 1970s.
  • Mitochondrial and chloroplast ribosomes are the same size as bacterial ribosomes.
  • Ribosomes are naturally made up of two subunits, small and big, which are both classified by the S unit based on their sedimentation rates.
  • As a eukaryotic cell, the plant cell possesses big complex ribosomes with larger S units, as well as four rRNAs containing over 80 proteins. The S unit of the 60s (28s rRNA, 5.8s rRNA, and 5s rRNA) contains 42 proteins in the big subunit. The tiny subunit, which is made up of one rRNA and 33 proteins, has a sedimentation rate in the 40s.
  • The ribosomal subunits assemble in the nucleolus of the cell and are then transported into the cytoplasm through nuclear pores. Protein synthesis takes place mostly in the cytoplasm (translation).

Functions of ribosomes in plant cells

  • The main purpose of ribosomes, which include an RNA component, is to manufacture proteins for biological processes, including cell repair.
  • Ribosomes serve as catalytic agents for peptidyl transfer and peptidyl hydrolysis to provide strong binding for portion extension.
  • Ribosomes, which are present in the cytoplasm of cells, are in charge of translating genetic information into sequences of amino acids and the assembly of protein polymers from amino acid monomers.
  • They’re also employed in protein folding and assembly.

Storage granules of plant cell

  • The cytoplasmic membrane and the plastids of plant cells contain these aggregates.
  • They are inanimate plant organelles that store starch as their principal purpose.

Storage granules in plant cells have a variety of functions.

  • They serve as food storage areas.
  • They store carbohydrates for the cell as glycogen or carbohydrate polymers.
  • They naturally store starch granules for the plant cell.
  • In addition, they provide energy for the production of new cellular materials by fueling cell metabolisms that entail chemical processes.

Plant cell Golgi bodies definition

  • The Golgi complex, commonly referred to as the Golgi apparatus, is a membrane-bound organelle of eukaryotic cells. They are located around the nucleus, right adjacent to the endoplasmic reticulum.

Structure of the Golgi bodies in a plant cell

  • Microtubules in the cytoplasm keep Golgi bodies together, and a protein matrix holds them together.
  • They are formed up of cisternae, that are flattened stacked pouches.
  • Plant cells have several Golgi bodies traversing the cytoskeleton and endoplasmic reticulum, but animal cells contain just a few (1-2).
  • The Golgi bodies are divided into three sections:
  • The cisternae nearest to the endoplasmic reticulum are known as the Cis Golgi network, also known as Goods inwards. The Golgi apparatus’ entrance section is also known as the cis-Golgi reticulum.
  • The middle or Golgi stack is the main processing region of the cisternae, located in the centre layer.
  • The Goods outwards cisternae network is another name for the Trans Golgi network. The cisternae endoplasmic reticulum is the farthest away from the endoplasmic reticulum.

Functions of the Golgi bodies in a plant cell

  • The Golgi bodies provide a variety of tasks, including being a neighbouring organelle to the endoplasmic reticulum and delivering cell products. They are present as a membrane complex in the centre of the cell’s secretory pathway, largely processing, distributing, and storing proteins for usage by the plant during stress reactions and others in leguminous plants such as cereals and grains.
  • The membranous sac compartments provide a variety of chemically linked tasks. As new proteins move through the Golgi bodies on their way out of the endoplasmic reticulum, they pass through the three compartments, each of which produces a distinct response on the molecules, altering them in various ways (e.g.
  • Protein molecules are cleaved into oligosaccharide chains.
  • Sugar moieties from various side chains are attached to protein components.
  • Fatty acids and phosphate groups are added to the elements, while monosaccharides are removed.
  • The cell vesicles transfer protein molecules from the endoplasmic reticulum into the cis compartment, where they are changed and packed before being transported to the next compartment. The vesicle’s transit is aided by the addition of a tag, such as a phosphate group or specific protein molecules, which directs it to its next destination.
  • After the proteins and lipid molecules have been delivered by the vesicles, the Golgi bodies are in charge of assembling the product and conveying it to its ultimate destination. The presence of enzymes in the Golgi bodies of plants aids this process by attaching to the sugar moieties on proteins, packing them, and delivering them to the cell wall.

Plant cell nucleus definition

  • The nucleus is a cell’s information core. It’s a particularly complex organelle whose main job is to store the genetic information of the cell.
  • It is also in charge of coordinating the cell’s operations, such as cell metabolism, cell growth, protein and lipid synthesis, and, more broadly, cell reproduction through cell division processes.
  • On the chromosomes, the nucleus carries the cells’ genetic information, known as Deoxyribonucleic Acid (DNA), (special thread-like strands of nucleic acids and proteins found in the nucleus, carrying genetic information).

Structure of the nucleus of the plant cell

  • The nucleus is spherical in form and located at the centre of the cell. It takes up around ten percent of the cell’s volume.
  • The nuclear envelope is a double-layered membrane that separates the contents of the nucleus from those of the cell cytoplasm.
  • Chromatins, DNA, which produces cell chromosomes during cell division, and the nucleolus, which synthesises cell ribosomes, were among the nuclear materials.

Functions of the nucleus of the plant cell

  • The cell nucleus’ primary duty is to serve as the cell’s control centre.
  • The nucleus and its contents are separated from the cytoplasmic organelles by the existence of the nuclear membrane. The nuclear envelope, which contains numerous nuclear pores, provides selective permeability to and from the nucleus and cytoplasm via this nuclear membrane.
  • A network of microfilaments and microtubules connects the nucleus to the location of protein production, the endoplasmic reticulum. Depending on the cell’s specialisation, these tubules stretch all across the cell, generating elements and compounds.
  • The chromatids are another name for chromosomes. They can be present in practically every cell’s nucleus. They contain six long strands of DNA that are split into 46 distinct molecules that join together to form two chromosomes, each with 23 molecules. It is joined with other proteins to produce a compact structure of dense fiber-like strands called chromatins to generate a functioning DNA unit.
  • Each of the six DNA strands wraps around histones, tiny protein molecules generated by the ER. Nucleosomes are bead-like structures made up of them. The negative charge of DNA strands is balanced by the positive charge of histones. DNA that hasn’t been utilised gets folded and stored for later use.

Chromatins are classified into two types:

  1. Euchromatin:It is the active component of the DNA that is responsible for RNA transcription and the production of cellular protein, which is necessary for cell development and function.
  2. Heterochromatin:Heterochromatin is the inactive section of DNA that contains unusable compressed and condensed DNA.

During cell division, chromatin evolves into different forms of the nucleus during chromatin formation. Inside the nucleus, chromatin fibres take on several shapes during the course of a cell’s existence. Euchromatin is expressed to begin transcription during the interphase stage of cell division. During replication, the chromatins split and make their own copies, exposing the chromatins to create more specialised structures known as chromosomes. These chromosomes split and separate, resulting in the development of two new complete cells, each with its own genetic information.


  • It is a membraneless sub-organelle in the nucleus of a cell.
  • Its main job is to make cell ribosomes, which are the organelles that make cellular proteins.
  • There are around four nucleoli in the cell.
  • When chromosomes are brought together immediately before cell division, the nucleolus is produced.
  • During cell division, the nucleolus vanishes.
  • The nucleolus is associated with cell ageing, which has an impact on living organisms’ ageing.

Nuclear Envelope

  • It consists of two membranes that are separated by perinuclear space. The endoplasmic reticulum is connected to the space.
  • It controls the molecules that enter and exit the nucleus into and out of the cytoplasm via its perforated wall.
  • A layer of proteins known as nuclear lamina, binding chromatin, and other nuclear components lines the inner membrane.
  • During cell division, the envelope disintegrates and vanishes.

Nuclear Pores

  • They are perforations in the cell envelope that govern the movement of biological substances like proteins and histones into and out of the nucleus and cytoplasm, respectively.
  • They also let DNA and RNA enter the nucleus, giving energy for the genetic materials to be synthesised.

Plant cell peroxisomes definition

These are small, highly dynamic structures with a single membrane harbouring enzymes responsible for hydrogen peroxide synthesis.

They play important roles in primary and secondary metabolisms, as well as photorespiration and cell formation, as well as reacting to abiotic and biotic stress.

The peroxisomes’ structure

  • Peroxisomes are tiny, measuring 0.1–1 m in diameter.
  • It consists of compartments with granulated matrixes.
  • They have a single membrane layer as well.
  • They are located in a cell’s cytoplasm.
  • The compartments aid the cell’s many metabolic processes, allowing it to maintain its cellular functions.

Functions of the peroxisomes

  • Hydrogen peroxide production and degradation
  • Fatty acid oxidation and metabolism
  • Carbon elements are broken down.
  • Photorespiration and nitrogen absorption for certain plant functions
  • Defending against infections by providing defensive mechanisms

The existence of lysosomes in plants has been a point of contention for a long time, with scant evidence of their structural presence. In plants, lysosomes are thought to partly develop into vacuoles and partially into Golgi bodies, which accomplish the duties that lysosomes are supposed to conduct. Unlike in mammals, where lysosomes contain hydrolytic and digestive enzymes for breaking down harmful chemicals and eliminating them from the cell and digestion of proteins, respectively, these enzymes are present in the vacuoles and Golgi bodies in plants.

Incomplete differentiation has been compared to the multiprocesses that contribute to the creation of Golgi bodies from the endoplasmic reticulum, in which a brief period of lysosomal exudation occurs just before the Golgi bodies are completely formed.

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Plant peroxisomes by Mano S., Nishimura M.




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