Plant cell

What are plant cells?

The vegetables cells They are the cells that make up all the organisms we know as plants: roses and daisies, tulips and gladiolas, trees and grasses, the vegetables and fruits that we eat daily, mosses and algae , and many others.

Plants are made up of plant cells. Plant cells are eukaryotic cells that have cellulose cell wall, nucleus, chloroplasts, mitochondrial vacuole, endoplasmic reticulum, Golgi complex, peroxisomes, and other internal organelles..

Photosynthesis is one of the main functions that distinguishes plant cells from other cells in nature, since only plants have the ability to feed sunlight and water, producing their own food.

Characteristics of plant cells

Let's see the main characteristics of plant cells:

• They are eukaryotic cells, which means that they have their genetic material locked inside a coat or compartment called core and that also have other internal compartments surrounded by membranes.
• Have cellular wall; this distinguishes them from animal cells, which do not have. Its wall is composed of a kind of network or framework known as cellulose.
• They are photosynthetic, which means that they can produce their own food from the energy they obtain from the sun's rays and from the water that they collect with their roots from the ground.
• Have plastids, a group of organelles special that fulfill different functions and that, generally, contain pigments or other substances inside. Examples are chloroplasts (which have chlorophyll), amyloplasts (which have starch), chromoplasts (which have red or yellow pigments), and leukoplasts (which have no pigments).
• They have a great vacuole inside, where they store a lot of water, minerals, enzymes and other compounds.

Parts of the plant cell (organelles)

Just like animal cells and fungal cells, plant cells have many internal parts, just as our body has different organs that perform different fundamental functions for our life. Let's see what they are:

Cell wall and plasmodesmata

Plant cells are surrounded by a somewhat rigid cell wall, capable of withstanding great internal pressures. This wall is characteristic of plant organisms and is formed by a compound known as cellulose.

The cell wall is the first “layer” that we observe if we look at a plant cell from the outside in..

In multicellular plants, cells communicate with each other through "bridges" or "channels" that are formed between the walls of neighboring cells; these channels are known as plasmodesms.

It is said that through plasmodesmata, plant cells form a kind of continuous cytosol, so the transfer of substances from one part of a plant to another is quite simple.

Plasma membrane and cytoskeleton

The cell wall gives the plant cells their shape and also protects what is further inside. Immediately after the wall is the plasma membrane, which shares the same characteristics as the membrane of animal cells..

The plasma membrane encloses the cellular components and, in addition, forms a semi-permeable barrier, that is, a kind of filter that allows some substances to pass through and prevents the passage of others.

• The cytoskeleton

Under the plasma membrane of plant cells is the cytoskeleton, that works just like bones work to support our weight and give our body structure.

The cytoskeleton is a kind of scaffold molecular structure that supports the internal structure of cells and, at the same time, orders intracellular components and facilitates the transport of vesicles and the movement of organelles within the cell.

Cytosol

It is a kind of fluid that is found inside cells. In the cytosol there are large amounts of water, salts, proteins and other dissolved molecules.

All internal organelles of plant cells are suspended in the cytosol, just as the yolk of an egg is "suspended" in the white.

The cytosol provides adequate space for numerous chemical reactions that contribute to cellular life to occur and, furthermore, facilitates the communication between the organelles.

Nucleus: nuclear envelope, nucleoplasm, chromatin, and nucleolus

Like any eukaryotic cell, plant cells have a nucleus inside them. The nucleus is a very special organelle, because inside it contains all the information that allows a cell to be a cell.

The information that is stored in the kernel is packed into structures called chromosomes, which are compact chromatin fibers.

Chromatin is a complex made up of proteins and deoxyribonucleic acid (DNA), which is the genetic material where all cellular information is stored..

• The nuclear envelope, envelope or lamina

The nucleus has its own membrane and this is known as nuclear envelope, nuclear lamina or nuclear envelope. Communication between the nucleus and the cytosol depends on the nuclear pore complexes, which are a kind of "holes" that allow the passage of certain substances from one side of the nucleus to the other.

• Nucleoplasm

Just as within the plasma membrane is the cytoplasm or cytosol, within the nuclear envelope is the nucleoplasm, which is the medium where DNA and its related proteins are found..

• The nucleolus

The nucleolus is an internal region of the nucleus where some proteins are found and that is responsible for producing other molecules known as ribosomal RNA (ribonucleic acid), whose functions consist of the production of cellular proteins.

Endoplasmic reticulum

It is a membranous organelle that is closely related to the nuclear envelope. Participates in the processing and distribution of some cellular proteins, especially those that are destined for the organelle membranes or the plasma membrane.

Golgi complex or apparatus

It is another membranous organelle, but this consists of a series of saccules or cisterns flattened.

Unlike the endoplasmic reticulum, the Golgi complex is not associated with the nuclear membrane and its main function is to process and package proteins and other macromolecules for export..

It also works in the synthesis of some molecules such as glycoproteins, hemicelluloses and other components of the cell wall..

Vacuole and Tonoplast

Although animal cells can also have a vacuole, the vacuole of plant cells is one of the most attractive organelles, occupying a large part of the plant cell volume.

The vacuole is a multifunctional organelle, as it participates in the storage of substances, in the digestion of different compounds, in the regulation of the concentration of salts and also in the maintenance of the shape and size of plant cells..

• Tonoplast

The membrane that delimits the plant vacuole is known as toneplast and, like the nuclear envelope or plasma membrane, this membrane allows the selective passage of substances from the cytosol into the vacuole and vice versa.

Mitochondria

They are the cellular energy centers, the power sources of all eukaryotic cells. They have an elongated shape, very similar to that of some bacteria. In its interior, chemical reactions occur that allow cells to breathe and obtain energy in the form of ATP.

Mitochondria are one of the most important organelles in a cell. They have their own DNA, but some of the proteins inside are produced by the DNA in the nucleus..

In plants these special organelles participate in the production of energy from food compounds generated during photosynthesis.

Plastids

Plant cells are distinguished from animal cells by two particular elements:

• The presence of a cellulose cell wall.
• The organelles we know as plastids, mainly of those called chloroplasts.

Plastids are large organelles that, like mitochondria, have their own DNA. These perform different functions in the cell, depending on the type of components they have inside..

• The chloroplasts They are one of the most important plastids, as they are responsible for the photosynthesis process: obtaining carbohydrates (food) from the energy of the sun's rays and the water in the soil. Inside it is chlorophyll, which is a special pigment for photosynthesis.
• The amyloplasts participate in the storage of starch in some types of fabrics, chromoplasts store pigments and etioplasts are the chloroplasts that have lost chlorophyll due to the absence of light.

Microbodies: glyoxysomes and peroxisomes

Microbodies are small organelles, hence their name. They do not have their own DNA and participate in various cellular functions.

• The peroxisomes Vegetables are responsible for the elimination of some toxic substances such as hydrogen peroxide (H2O2), and they also participate in the oxidation and synthesis of different molecules.
• The glyoxysomes are modified peroxisomes found in plant cells that are responsible for the recycling of carbon atoms derived from photosynthesis.

Cell functions

Cellular division

The development and growth of plants depends on the multiplication, development and differentiation of the cells that make up their tissues..

Multicellular plant organisms have a large number of cells and many of these are constantly dividing to renew damaged tissues, to promote the growth of the plant body, etc..

Medium

Plant cells, just like the building blocks form its structure, are responsible for giving structure and shape to plant tissues..

Support is a very important function of plant cells, since it allows the formation of tissues that, at the same time, establish the shape of plants.

Communication

Like all cells in nature, plant cells communicate with their environment and with adjacent cells in the same tissue, allowing them to develop properly and respond to external changes when necessary..

Communication between plant cells occurs through the exchange of molecules between neighboring cytoplasms (through plasmodesmata) and is very important for plant development..

Defending

Although it does not work in the same way as in animals, plant cells also have defense functions against the pathogens that they constantly face.

These functions are "individual" and have to do with the production of some substances for counter to invading microbes, with the reinforcement of the cell wall to prevent the entry of pathogens and the "sacrifice" of cells or organs that are adversely affected by a pathogen.

Photosynthesis

Without a doubt, photosynthesis is one of the most important functions of plant cells. This is the process of producing carbohydrates (food) from the energy contained in the sun's rays and the water molecules absorbed from the soil by the roots..

With the exception of cells in roots, cells of the vascular system, and some cells in stems, all plant cells can photosynthesize..

Examples of plant cells

Here are several examples of plant cells:

• Xylem cells: xylem is the tissue of plants that is responsible for transporting water from the ground. It is formed by very special elongated cells that, in reality, reached a point of differentiation such that they died, leaving only their structure for the conduction of water.
• Meristematic cells: they represent a reduced set of small cells that divide and, when they do so, participate in the growth of the plant body. There are meristematic cells in the root and stem and from these the cells of these tissues are formed.
• Stomata and occlusive cells: stomata are structures found mainly on plant leaves. They are analogous to the mouth or nose of animals, as plants use them to exchange gases with the environment that surrounds them. Stomata are made up of special cells (occlusive cells) that have an elongated shape, capable of forming a pore that closes or opens depending on how much water these cells have inside..
• Epidermal cells: just as animals have skin that covers them and protects them from external adversities, plants also have a set of specialized cells to form the epidermis. These are elongated cells that have, in addition to the cell wall, an outer layer known as cuticle, that helps them to participate in the protection against perspiration.
• Parenchymal cells: they are the most abundant cells in plants, although they are among the least specialized. They fill the available spaces in plant tissues and therefore have important functions in the structure of plant tissues.

Other topics of interest

Animal cell

Prokaryotic cell

Cell types

References

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4. Nabors, M. W. (2004). Introduction to botany (No. 580 N117i). Pearson,.
5. Solomon, E. P., Berg, L. R., & Martin, D. W. (2011). Biology (9th edn). Brooks / Cole, Cengage Learning: USA.