What are non-specialized cells in plants

Episode 008 - Cell Types in Plants | Layout and function

Content of the episode:

  • In episode 006 - The structure of the leaf | We have already mentioned some tissues or cell types of plants with leaf cross-section!
  • For example, there would be closing tissue such as the epidermis and base tissue such as the palisade parenchyma.
  • In today's episode I would like to complete the list and List and explain all other tissue types or cell types of plants!

How are different cell types in plants created?

Most plants can reproduce in two different ways:
On the one hand there is generative reproduction (sexual reproduction) and on the other hand vegetative reproduction (asexual reproduction).

With generative reproduction, a fertilized egg cell finally develops into the finished plant organism through several cell division steps.

As we learned from podcast episode 004 - Determination and Differentiation in Plant Cells:

"Although all cells of an organism arise from a single fertilized egg cell, an organism consists of different organs and tissues, the cells of which are structured differently!"

"In the course of development, there is a so-called" differentiation "of the cells in both plants and animals, and different cell types are created!"

Today we are discussing which cell types these are in plants!

Cell types of plants

The two major groupings of tissues

Basically, a distinction is made between two superordinate tissue types:

  1. Formation tissue (meristeme)

    • The Cells the formation tissues are undifferentiated, have no vacuoles and are permanently divisible!
    • They are used exclusively for the formation of new cells, which then differentiate over time.
    • A distinction is also made between educational fabrics primary and secondary meristems.
      → The primary meristems descend directly from the zygote.
      → Secondary meristems are educational tissues that have arisen from cells that have already been differentiated.
  2. Permanent fabric

    • A fabric is called permanent fabric if the Cells of the fabric no longer divisible are!
    • Since only the cells of the meristems are able to divide, all other types of tissue fall under the term permanent tissue!

There is accordinglymany different types of permanent fabrics!

An overview of the various permanent fabrics

Let's go over the different cell types in plants:

  1. Finishing fabric

    Structure of the cells:
    → Thickened cell walls / in some cases also lignified / corked cell walls
    → Central vacuoles in epidermal cells
    → Cuticle on the epidermal cells
    → Water-repellent corked cells in the periderm
    → Partly dead cells

    Function:
    → Protection against water loss through evaporation
    → Protection against UV and solar radiation
    → Protection against physical injuries
    → Protection against parasites / pests

    Occurrence in plants:
    → The epidermis is the primary closure tissue of the plants.
    → ThatPeriderm is the secondary closure tissue that occurs during the "Secondary growth in thickness"arises.
    Secondary growth in thickness is the subsequent thickening of the stem axis of plants that are growing in size, to form additional conduction tissue and strengthening tissue.
    The epidermis cannot withstand this increase in cross-section (permanent tissue such as the epidermis does not grow with it because it cannot divide!), Which is why it is replaced by a layer of cork, the periderm.

  2. Basic tissue (parenchyma)

    Structure of the cells:
    → Little differentiated, living cells
    → Thin cell walls
    → Many chloroplasts in the assimilation parenchyma / palisade parenchyma
    → Many leukoplasts (storage organelles) in the storage parenchyma
    → "Intercellular" in the sponge parenchyma

    Function:
    → Assimilation parenchyma / palisade parenchyma: Photosynthesis
    → Sponge parenchyma:Controlled gas exchange, transpiration, ventilation (intercellular system)
    → Storage parenchyma: Storage of macro and micronutrients

    Occurrence in plants:
    → Assimilation parenchyma / palisade parenchyma and sponge parenchymaoccur mainly in the leaves of plants.
    Storage parenchymaare found, among other things, in the roots (sometimes in the form of rhizomes) and partly in the stem and leaves.

  3. Conductive fabric / conductive fabric

    Structure of the cells:
    Xylem:
    → Dead, elongated cells
    → No cytoplasm
    → Partly to completely lignified cell walls
    → Line up of cells that have joined together to form conduction paths through pits or completely disintegrated transverse walls
    Phloem:
    → Living, elongated cells
    → Unlignified cell walls
    → Contain cytoplasm
    → Line up of cells whose transverse walls are perforated

    Function:
    Xylem:Conducts water and the nutrient salts dissolved in it
    Phloem: Conducts the assimilates (photosynthesis products)

    Occurrence in plants:
    → Both conductive tissues run through the entire plant organism.

  4. Strengthening fabric

    Structure of the cells:
    Collenchyma:
    → Living cells
    → Elongated cells with partially thickened cell walls
    Sclerenchyma:
    → Dead cells
    → Extremely reinforced cell walls due to the storage of cellulose and lignin (wood pulp)
    → The sclerenchyma can be in the form of stone cells or sclerenchymal fibers
    → Stone cells are lignified cells that e.g. form the shells of nut fruits
    → Sklerenchymal fibers are elongated, lignified cells that usually join together to form fiber bundles and absorb bending loads

    Function:
    → Strengthening fabrics give the plant stability and protect it from tensile and bending loads

    Occurrence in plants:
    → Sklerenchyma occurs only in woody plants and permeates the entire plant organism.
    → Herbaceous, unwooded plants gain stability through a combination of cell sap pressure (turgor) and collenchyme.

  5. Absorbent fabric (root hair)

    Structure of the cells:
    → Living cells
    → Very fine, thin cell walls without a cuticle
    → Long, hair-like cells (root hairs)

    Function:
    → Serve to absorb water and the nutrient salts dissolved in it from the soil

    Occurrence in plants:
    → Root hairs are only ever in the immediate vicinity of the root tips.
    → If the root grows and pushes itself further into the ground, new root hairs are formed in the immediate vicinity of the root tips and the older ones die off.

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Christian Schweda

Podcast host

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