Define Plant cell, 7 Parts, structure, and Its function of plant cell
Define Plant cell
Cells are the basic building blocks of all living things. They differ in size, shape, and function. There are similarities in the formation of the plant and animal cells, such as cell membranes, cell plasma, and cell nuclei. In-plant cells, in addition to the components described, the cell wall, chloroplasts with chlorophyll, and vacuoles (cell sap spaces) are present. Cells feed, they grow and divide. Nutrition can be autotrophic (cells with chloroplasts) or heterotrophic.
Which organelles are found only in plant cells?
Plastids are only plant-specific organs. Plants are autotrophic due to the presence of green plastids called chloroplasts and represent the process of photosynthesis. Colorless plastids called leucoplasts store foods as starch, proteins, and fats and non-green colored plastids called chromoplasts are important for the pollination and dispersal of fruits.
A chloroplast is an organ found only in plant cells. It is a plastid that contains chlorophyll and also contains photosynthesis.
What is a plant cell?
Plant cells are multicellular eukaryotic cells that make up a plant (a group of eukaryotes belonging to the Plantae kingdom that can synthesize their food using water, sunlight, and CO2). Like eukaryotic cells, they have a defined nucleus with special structural organelles that enable them to function properly.
The plant cell has a well-defined cell wall made of cellulose components, plastids that perform photosynthesis and storage of carbohydrates in the form of starch, central vacuoles to regulate the turgor pressure of the cell, and a nucleus that controls the general mechanisms of the cells including the reproduction of the plant cells. Several plant cell organelles are well defined and described in Plant Cell Definition, Labeled Diagram, Structure, Parts, Organelles.
Characteristics of the plant cell
Plants are made up of two structural systems, i.e. the scion system and the root system, with the scion system consisting of structures located above the ground including leaves, stems, fruits, flowers, while the root system consists of roots and tubers and rhizobial structures located below the earth and whose origin is the growth of plants.
- These systems are structured differently and are defined by groups of specialized mature cells that perform a wide range of functions ranging from protection, support, metabolism, reproduction, and plant growth to development. For example, plant cells are formed on the meristem that multiplies and grows for plant tissue. These fabrics are:
- Skin tissue – This tissue lies on the surface of plants and is made up of epidermal cells that protect the plants from water loss.
- Ground tissue – This is made up of the root vasculature and epidermal system, which is mainly composed of parenchymal, collenchyma, and sclerenchyma cells, which are responsible for photosynthesis in plants, storage of water and food, and the plant support system.
- Vascular tissue – This tissue is made up of xylem, phloem, parenchyma, and cambium cells. Its functions include the transport of water (xylem), the transport of food (phloem), minerals, and hormones in the plants the plant cells
Plant cells multiply through cell division, a mechanism known as mitosis that occurs within its core. This begins with the meristem, which is located at the root tip and/or on the shoot of vascular plants. Meristems at the tips are called the apical and lateral meristems. Apical meristems are responsible for the production of the roots, while the lateral meristems are responsible for the secondary growth of the trunk wood and the cork.
In addition to the cell division of the cells, which leads to the formation of tissues that eventually form a plant, there are other characteristics of the plant cells that are important for plant growth and metabolism.
- Presence of a cell wall combined with a plasma membrane. It consists of cellulose, hemicellulose, and pectin. The cell wall indicates the cell shape, cell protection, and the mediation of cell interactions.
- They have dynamic single-membrane central vacuoles that are filled with water to maintain the cell’s turgor pressure, regulate the movement of cell molecules in the cytosol, store nitrogen and phosphorus, and facilitate the digestion of stored cells proteins.
- They have a plasmodesma, a continuous porous structure that extends from the endoplasmic reticulum and enables cell-cell communication.
- Plant cells also have plastids. The most common plastid known as chloroplasts is made up of chlorophyll, a green pigment responsible for capturing light energy and converting it into chemical energy that plants use in photosynthesis. Other plastids include amyloplasts for storing starch, glioblasts for storing fats, and chromoplasts for synthesizing and storing pigments.
- The plant cells undergo cell division by forming the phragmoplast matrix for building up cell plates in cytokinesis.
- In contrast to animal cells, plant cells in particular lack cilia, flagella, and centrioles.
What are the different types of plant cells?
As described above, plant cells come from the tip of the plant roots. The development of other cells is facilitated by the initial proliferation that occurs on top of the undifferentiated meristematic cells to form other specialized cells and cellular tissues.
7 different types of plant cells
- Parenchymal cells
- Collenchyma cells
- Sclerenchyma cells
- Xylem cells
- Phloem cells
- Meristematic cells
- Epidermal cells
Parenchymal cell definition
These are living undifferentiated cells that are found in various parts of the plant body.
They participate in various mechanisms of the plan, including photosynthesis, food storage, and waste secretion.
Experimental observation showed that they appear green.
Structure of parenchymal cells
They are living thin-walled cells with impermeable walls that are undifferentiated. They do not have a special structure, so they easily adapt and differentiate into a multitude of cells that perform different functions. There are two types of parenchymal cells
- Palisade parenchyma
- Ray parenchyma
Palisade parenchyma cells are columnar elongated structured cells that are found in a variety of leaves and lie beneath the epidermal tissue. Palisades are tightly connected cells in layers of mesophyll cells found in leaf cells.
Ray Parenchyma – The ray parenchyma has both radial and horizontal arrangements that are mainly found in the stem of the plant.
Functions of the parenchymal cells
- Parenchymal cells are closely connected to the surface epidermal cells, which largely contribute to the penetration and absorption of light and to the regulation of gas exchange.
- The permeable wall enables the transport of small molecules between the cells and the cell cytoplasm.
- The palisade parenchyma in combination with a spongy mesophyll cell, which is located under the layer of epidermal tissue, supports the light absorption used in photosynthesis.
- Radiation parenchyma cells are found in wood rays that transport materials along the stem of the plant.
- The parenchymal cells are also found in large numbers in the xylem and phloem of vascular plants and help transport water and food in the plant.
- Some are also involved in the biochemical secretion of nectar and the production of secondary elements that serve as protective materials from feeding herbivores.
- And these parenchymal cells, found in tubers like potatoes and legumes, help with food storage.
Collenchyma cell definition
- They are elongated cells that are located below the epidermis and/or in young plants on the outer layers of their stems and leaves.
- They come to life after-ripening and are derivatives of the meristems. They are located in the corners of the vessel and/or plant stem.
- They occur in the peripheral area of the plant and do not occur in the plant roots.
- When observed experimentally, they appear red.
Structure of collenchyma cells
- These are cells that are long with a primary thick cell wall. The cell wall is usually irregular and consists of cellulose and pectin molecules
- At some point during maturity, they resemble parenchymal cells, which transform into collenchyma cells. When some cells accumulate, the Golgi bodies, along with the endoplasmic reticulum, form the primary cell wall. When two cells fuse, they form a thin primary wall that is no different from collenchyma cells.
The more the cells accumulate and fuse, the stronger they form a highly irregular functional primary cell wall. These newly formed cells are elongated to support the plant’s growth. However, the primary wall does not contain lignin, a polymeric organic complex that forms strong structural tissues of vascular plants that give it rigid support and prevent rot, especially in wood and bark.
Types of collenchyma cells
There are four types of collenchyma based on wall thickness and cell arrangement
- Angular collenchyma
- Ring collenchyma
- Lamellar collenchyma
- Lacunar collenchyma
- The cells appear to have an angle and a polygonal shape.
- The cells are thickened at the corners of the cell
- The cells have no intracellular spaces because they are tightly packed together
- They are located below the epidermis as the hypodermis
- They are the most common type of collenchyma
The walls are thickened evenly.
The cells appear to be circular
- The cells are thickened on the periphery so that they appear tangentially arranged in rows
- They are tightly packed together and therefore have no intracellular spaces.
- They are often formed and found in the petioles of the leaf.
- These are cells that are formed spaciously and leave intracellular spaces between them.
- The cell wall thickens around the intracellular spaces
- They appear spherical
- They are formed and found in the walls of the fruit
Functions of the collenchyma cells
- As living cells in plant tissues, they support the plant areas that grow and mature in length. Since the cell wall lacks lignin, it remains supple and gives the plant parts such as young stems, young roots, and young leaves plastic (elastic) support.
- They provide plant tissue flexibility and tensile strength so that the plants can flex.
- They also make the plant parts grow and elongate.
- Collenchyma can combine with the chloroplast and carry out the process of photosynthesis.
Definition of sclerenchyma cells
- These are collenchyma cells that have a cell wall agent that plays an important role in hardening their cell wall.
- Therefore, these are mature collenchyma cells with a secondary cell wall above the primary cell wall.
- They occur in all plant roots and are important for anchoring and supporting the plants.
Structure of sclerenchyma cells
- They have a lignified cell wall, which makes them extremely hard.
- These make them stiffer compared to the parenchymal and collenchyma cells.
- They also have suberin and cutin which makes them waterproof.
- Due to their stiffness and waterproof properties, they do not live long as no materials for cell metabolism can be exchanged to maintain their longevity.
- Therefore, in the event of a full development of their functional maturity (a phase for the formation of cytoplasm), they are dead.
Types of sclerenchyma cells
There are two types of sclerenchyma cells
- Fibrous sclerenchyma cells
- Sclereid sclerenchyma cells
Functions of the sclerenchyma cells
- Due to their thickened cell walls, they provide protection and support for the tissues of other plants, especially the tree trunks and fibers of large herb trees.
- The hardened cell wall discourages herbivores. The uptake of the hard cell wall leads to damage to the digestive tract of insects in the larval stage, especially in peach fruits.
- Fibers found by sclerenchyme are used to make fabrics, threads, and yarns.
Xylem cell definition
Xylem cells are complex cells found in the vascular tissue of plants, mainly in woody plants.
Structure of xylem cells
- You have two elements for conduction: tracheids and vascular elements
- They have tracheids, vessels that carry water and minerals from the roots to the plant leaves.
- Tracheids are elongated, slender vessels that are lignified. Hence, they have a hardened secondary cell wall that specializes in drawing water out of the roots.
- The tracheid also has overlapping cock ends arranged in an angel to allow cell-to-cell connection and communication.
- The vessel elements enable the transport of water. They are hollow, shorter, wider than the tracheids, but have no angel-shaped end plates, which is why they are aligned to form a continuous hollow tube 3 meters long
- The xylem cells are also combined with fibers and parenchymal cells, so they have a primary cell wall combined with a lignified cell wall, forming rings and looped networks with pits known as rimmed pits for conduction.
- The outlined pits are areas in the cell wall where primary cell wall materials are deposited and they allow water to move between the xylem cells.
- Gymnosperms, ferns, and pteridophytes have tracheids, while flowering plants have vascular elements.
Functions of the xylem cells
The main function of the xylem cells is to carry water and soluble nutrients, minerals and inorganic ions from the roots of the plants and their parts upwards. With the help of the xylem sap, these elements flow freely through the xylem tracheids and vascular elements.
Phloem cell definition
- These cells are located outside the xylem layer of the cells. They come to life at maturity because they need the energy to move materials.
- They are used to transport food from the plant leaves to other parts of the plant.
- They also have flaccid cell walls, so they lack the tensile strength that allows them to move materials under high pressure.
Types of phloem cells
There are two types of phloem cells:
- Sieve tube elements and accompanying cells
- Sieve cells
Sieve tubes and accompanying cells
- These are the cells that control the metabolism of the cells and are associated with a large number of plasmodesmata.
- Screen tubular members are shorter and wider and are continuously placed from end to end into the screen cells where they are tightly packed together.
- This concentration allows the dissolved materials to move faster within the sieve tubes and sieve cells. The core of the sieve tube elements disintegrates, ribosomes disappear and the vacuole membrane collapses at maturity.
- The companion cells help move materials in and out of the sieve tube elements. Characteristically, the sieve tubes have phloem (P) proteins on the cell wall and callosis and together heal injuries caused to the sieve tubes.
- They are the primitive part of the phloem found in ferns and conifers.
- They are structurally long with tapered overlapping ends. They have pores all over their cell wall that are surrounded by callose (a carbohydrate that repairs the pores after an injury).
- They connect to protein cells to help transport materials into the phloem.
- This is the place where dissolved food flows, e.g. B. sucrose
Functions of the phloem cells
It transports dissolved food and organic materials through the plants as it can move the materials in all directions of the plant depending on the age of the plant.
Meristematic cell definition
- They are also known as meristems.
- These are the cells in a plant that continuously divide throughout the life of a plant.
- They have a capacity for self-renewal and a high metabolism to control the cell.
Structure of the meristematic cells
- These are cells that divide, creating the parenchymal, collenchyma, and sclerenchyma cells.
- They have a thin wall and no central vacuole and are made up of immature plastids.
- Your protoplast is tightly filled.
- They are cubic with a large core.
- They have high metabolic activity
- They are clamped tightly together, so they have no intercellular space.
- They play an important role in plant growth in width and length.
Types of meristematic cells
There are three types of meristematic cells classified according to the tissue in which they exist.
Apical meristems – they are located at the tips of the roots and stems that have started to grow, and they add to the length of the plant
Lateral meristems – they are located in the radial part of the stem and roots and contribute to the thickness of the plant
Intercalar meristems – they are located at the base of the leaves and contribute to the size variance of the leaves.
Functions of the meristematic cells
- They play an important role in the length and width of the plants
- They also give differences in the size of the plant leaves.
- They differentiate and mature into permanent tissues of the plants.
Epidermal cell definition
- These are the outer cells of the plants that provide protection from water loss, pathogenic invaders such as fungi.
- They are arranged close together with no intracellular spaces.
- They are covered with a waxy cuticle layer to reduce water loss.
- These cells cover the plant stems, leaves, roots and plant seeds.
Types of epidermal cells
Three types of epidermal cells play the primary role in protecting the plant from environmental factors such as high temperatures, pathogens, chemical stress, e.g. Radiation. They include:
- Pavement cells
- Stomatal protection cells
Structure and functions of epidermal cells
- These are the most common epidermal cells that cover all plants. They are poorly specialized, so they lack a defined form, so they have no special functions.
- The morphology of plaster cells varies from plant to plant, e.g. B. the leaves of dicots, which look like pieces of a puzzle and give the leaves mechanical strength.
- Patch cells found on the stem and other long parts of the plant appear to be rectangular with an axis parallel to the direction of plant expansion.
- The different morphologies are related to the functions that the pavement cells perform. For example, epidermal cells are formed by embryogenesis during the development of plant seeds.
- They prevent excessive water loss, the cells are packed tightly together and form a protective lining to protect other cells below.
- The functions of the lane cell include:
- Maintain the internal temperature of the plants
- They act as a physical barrier against pathogens and external damage from chemicals such as radiation
- They separate the stomata of the leaves.
Stomatal Guard cells
- Stomatic protection cells are available depending on the type of plant.
- They are highly specialized and have a defined shape that allows them to perform a wide variety of functions.
- There are two types of protective cells defined by structure, those that control water availability by opening and closing the stomata by maintaining turgor pressure, and those that regulate the exchange of gases in and out of the stomata of the leaves.
- The stroma protection cells also have chloroplasts. Hence, they have a functional effect on photosynthesis.
- These are also known as epidermal hairs that are found on top of the epidermal tissue. They are a specialized group of cells with well-defined shapes.
- They are large, about 300 µm in diameter.
- They play an important role in protecting plants from predators and pathogens by acting as trappers and poisoners for animal predators.
- These cells do not multiply by cell division but undergo endoreplication to expand their cell population.
Do you know how the first plant cell on Earth arose?
Plants are complex and originated in water. It is now accepted that the first plant cell originated from the biological fusion between cyanobacteria, bacteria that can perform photosynthesis, and protozoa, one of the most primitive nucleus single-celled organisms in Earth’s history. Is one.
Different work of plants
In this process, green plants containing foliage take their food in the form of glucose by taking organic material in the presence of sunlight and release oxygen into the atmosphere, that is, plants produce carbohydrates in the presence of water, light, chlorophyll, and ki.
The rate of photosynthesis is maximum in red light and minimum in violet light.
* Chlorophyll: It is the green pigment present in the green part of the plant. There is one atom of magnesium (dah) at the center of chlorophyll.
* It is an energy-generating process, in which chemical dissolution of food substances takes place and energy is obtained in the form of ATP (Z).
Oxidation of organic matter (glucose or other) occurs in the presence or absence of oxygen in the cell (mitochondria).
* Absorption: The absorption of the ground and organic nutrients is done by the follicles of the root, which reach into the root tissue.
* Excretion: The process of taking out the substances made in the metabolism from the plant or body is called excretion. The main excretory substances in a plant are carbon dioxide, oxygen, and water vapor.
In respiration, sugars and fats are oxidized and energy is released. In this process, ATP and BT2 are released. Respiration is a combined form of all the processes by which energy is produced in plants. During respiration, some part of the free energy is stored as ATP in the cell’s mitochondria. This energy, accumulated in the form of ATP, is used to carry out various biological functions of living organisms in the future.
Evaporation of water from the pneumatic parts of plants as vapor is called evaporation. In other words, transpiration is the action in which a plant flies from the surface as water vapor. Water is temporary in plants. A substantial amount of water is expelled through the foramen present on the lower surface of the leaf in the form of vapor. The action of transpiration helps reach the water upward from the root to the leaves.
Factors affecting transpiration:
- Light intensity: Increasing the intensity of light increases the rate of transpiration.
- Temperature: The rate of transpiration increases as the temperature increases.
- Humidity: The rate of evaporation decreases as humidity increases.
- Air: Transpiration occurs at a rapid rate when the speed of air is high.
Many mineral elements are necessary for the normal growth of plants. Due to deficiency or excess of any one mineral, many diseases or symptoms occur in the plant and their growth stops. The mineral salts of plants can be divided into two parts:
1. Large Nutrients: Plants require more of them. These include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, magnesium, calcium, etc.
2. Micronutrients: Plants need these in small quantities, such as chlorine, boron, copper, iron, manganese, molybdenum, zinc, manganese, etc.
Work of mineral elements and the effects due to their deficiency
* Carbon: Hydrogen, Oxygen: They are derived from carbohydrates, proteins, hormones, and fats in plants. Due to their deficiency, organic materials are not made in the plants.
* Nitrogen: It is present in amino acids, proteins, nucleic acids, alkaloids, cytochromes, and chlorophyll. Lack of nitrogen leaves plants dwarfed. When there is an excess of nitrogen, simplicity, and immunity in the plants are reduced.
* Potassium: This element is in the form of an enzyme, and is necessary for the movement of stomata (stomata) and protein synthesis. Disease immunity decreases when it is deficient. Therefore, sugarcane, potato, beetroot needs potassium more, and due to their deficiency, white and red marks are formed on the leaves.
* Phosphorus: This element is contained in a nucleic acid (Mn. Mn – Mn) – which is required for synthesis. Lack of it reduces the strength and quality in the plant, and the stems become weak due to a lack of new cells.
* Calcium: This element forms the middle plaque of the cell in the form of calcium pectate. Due to their deficiency, the central lobe of the cell wall is not formed.
* Sulfur: It is found in the enzyme-sugar of amino acids. It is necessary for the stalk of plants. Onion, garlic, radish, beetroot, groundnut, lime contain plenty of sulfur.
* Magnesium: It occurs in foliage and is a cofactor of many enzymes. Its deficiency causes the leaves to turn yellow.
* Zinc: Essential for making oxygen and for enzymes carbonic N-hydrase and alcohol D-hydrogenase. When they are deficient, the leaves become smaller. The disease of small yellow leaf in lemon is due to this reason.
* Manganese: This element is essential for the dissolution of light from water and fumigation synthesis and is an active factor of many enzymes. Due to its deficiency, chlorophyll is reduced.
* Cobalt: Necessary for symbiotic nitrogen fixation in plants of Leguminaceae clan. Nitrate will be reduced due to a lack of a pink substance called hemoglobin due to its deficiency.
* Molybdenum: It is essential for the metabolic activity of nitrogen. On lack of this, cauliflower has a whip-like tail and nitrogen fixation slows down the bacterial action.
* Copper: Ascorbic acid required for the synthesis of foliar is also found in oxidase. Lacking it