The Plasmodesmos Are intercellular organelles found in algae plants and cells. They can also be referred to as"bridges"between two plant cells.
Plasmodesms consist of pores or channels found between the individual cells of plants. They connect the simplistic space in the plant.
Plasmodesmo separates the outer membrane of the cells from the plant cells. The real space that separates the cells is called the demodulation. The demobulus has a rigid membrane running along the plasmodesm.
He cytoplasm Is found between the cell membrane and the demodulation. The entire plasmodesm is covered with a smooth endoplasmic reticulum of the connecting cells.
Plasmodesms are formed during periods of cell division in plant development. Primary plasmodesms are formed while the cell wall and the endoplasmic reticulum are formed.
Secondary plasmodesms are more complex and have different functional properties in terms of the size and nature of the molecules that are able to pass through them.
Formation of plasmodesms
Primary plasmodes are formed when portions of the endoplasmic reticulum become trapped in the medial lamella. This occurs as the new cell wall forms between two newly divided plant cells; Eventually become cytoplasmic connections between cells.
Here, the cell wall is not thickened and depressions or thin areas are formed on the walls. These thin areas or spaces are usually joined between adjacent cells.
The plasmodesms can be inserted into existing cell walls between cells that are not divided, creating the secondary plasmodesmas.
Structure
A typical plant cell can have between 10 3 And 10 5 Plasmodesmos connecting their adjacent cells. Plasmodesms measure approximately between 50-60 nm in diameter at their midpoint.
The plasmodesms are constructed of three main layers: the plasma membrane, the cytoplasmic sleeve and the demitobulo. Plasmodesms can pass through cell walls up to 90 nm thick.
Plasma membrane
The plasma membrane portion of a plasmodem is a continuous extension of the cell membrane or plasma membrane and has a similar lipid bilayer structure.
Cytoplasmic Sleeve
The cytoplasmic sleeve is a fluid-filled space enveloped by a plasma membrane and is a continuous extension of the cytosol. The transport of the molecules and ions through the plasmodesmos occur through this space.
Smaller molecules such as sugars and amino acids, as well as ions, can easily pass through plasmodesms by diffusion.
They do not need to use additional chemical energy. Larger molecules, including proteins and RNA, can also pass through this sleeve in a diffuse way.
Demolition
The demulbulum is a flattened endoplasmic reticulum tube that passes between two adjacent cells. It is known that some molecules can be transported through this channel, but it is not the main route of plasmodesmotal transport.
It has been observed that some structures appear to divide plasmodes into smaller channels. These structures may be composed of myosin and actin, which are part of the cytoskeleton of the cell.
Activities and function
Among the plant cells can be found the formation of plasmodesms. A plasmodesmo is a channel through the cell wall that allows molecules and substances to move as much as necessary.
In addition, plasmodes also create cell-to-cell connections, allowing numerous cells to work together toward a common goal. For example, it allows the tissues, organs, and organ systems in plants to work together to grow.
Plasmmodes play roles in both cellular communication and molecular translation. Plant cells must work together as a part of a multicellular organism, in this case the plant.
This means that individual cells must work together to benefit the common good; Therefore the communication between the cells is crucial for the survival of the plant.
The problem with plant cells is that their cell wall is rigid and hard. It is difficult for larger molecules to penetrate through this cell wall, so plasmodesms are necessary to achieve this.
Plasmodesmos connect tissue cells to others, so they may have functional importance in the development and growth of tissue.
Actin structures help to move transcription factors and even plant viruses through the plasmodesms. It is known that some molecules can cause the channels of the plasmodesmos to open a little more.
Transport
Plasmodesms have been shown to carry viral proteins, siRNA, messenger RNA, viroids and genomes from cell to cell. An example of the viral movement of proteins is the MP-30 tobacco mosaic virus.
The MP-30 is thought to couple with the virus's own genome and transfer it from infected cells to healthy cells through the plasmodesms.
The florigenic protein moves from the leaves to the meristem through the plasmodesmos to initiate the flowering of a plant.
Plasmodesms are also used by cells in the phloem, and a simplistic transport is used to regulate the sieve tube of the accompanying cells.
The size of the molecules that can pass through the plasmodesms is terminated by the exclusion size limit. This limit may vary and may also be modifiable.
For example, by increasing calcium concentrations in the cytoplasm, the openings of the surrounding plasmodesms narrow and limit transport.
References
- Plasmodesmata: the bridge to somewhere in Science (2017). Retrieved from thoughtco.com
- Plasmodesmata: definition and function. Recovered from study.com
- Plasmodesma. Retrieved from wikipedia.org
- Plasmodesmata. Retrieved from biology.kenyon.edu.