The epidermis is found lining the surfaces of plants. The main function of the epidermis is to protect the plant body from dehydration and mechanical damage. The epidermis facilitates the gas exchange in plants as well. Xylem and phloem are two types of vascular tissues , transporting water and nutrients, respectively, throughout the plant body. The ground tissue is involved in the photosynthesis as well as storing food in plants.
Tissues in plants also can be divided into two as meristematic and permanent tissues. The meristematic tissues comprise actively dividing cell while permanent tissues comprise specialized cells. Various tissues in a stem of a plant are shown in figure 3. Cell: Cell is the smallest structural and functional unit of an organism, which is typically microscopic. Tissue: Tissue is any of the distinct types of material of which animals or plants are made, consisting of specialized cells and their products.
Cell: Cells are found in both unicellular and multicellular organisms. Tissue: Tissues are only found in multicellular organisms. Cell: Cell membrane, genetic material, cytoskeleton, and organelles such as mitochondria, nucleus, endoplasmic reticulum, Golgi apparatus, ribosomes, and lysosomes are the components of a cell. Tissue: A tissue comprises of similar types of cells, specialized for a unique function. Cell: Eukaryotic cells and prokaryotic cells are the two types of cells.
Tissue: Nerve tissue, muscular tissue, epithelial tissue, connective tissue, vascular tissue, and adipose tissue are the types of tissues. Cell: Cells are developed from mitosis and meiosis. Tissue: The cells in a tissue are developed from undifferentiated cells in the body. The basic unit that constitutes a living organism and facilities life functions is called a cell.
All living organisms comprise cells, and millions of microorganisms like bacteria are nothing but a cell capable of fully functioning on its own. Further, for complex multi-cellular organisms like plants and animals, these cells are organized into tissues, organs, and organ systems.
Cells are categorized as eukaryotic cells and prokaryotic primitive cells based on the presence or absence of the nucleus and other membrane-bound organelles.
Tissues are formed by cells of similar functions being grouped together. The tissues further develop into organs with specific functions. Tissues are hence similar to cells but more organized and specialized to perform a particular function.
In plants, there are broadly two types of tissues- meristematic tissues that contain actively dividing cells, and permanent tissues that are differentiated to do specific functions. In animals, the tissues are divided into specialized categories as follows. Epithelial Tissues - They form the outer surfaces, membranes, and linings of organs and organ systems. Muscle Tissues - They form the skeletal muscles, voluntary muscles, involuntary muscles, and cardiac muscles.
However, the multiple cell types within a tissue don't just have different functions. They also have different transcriptional programs and may well divide at different rates. Proper regulation of these rates is essential to tissue maintenance and repair. The spatial organization of the cells that form a tissue is also central to the tissue's function and survival.
This organization depends in part on polarity , or the orientation of particular cells in their place. Of course, external signals from neighboring cells or from the extracellular matrix are also important influences on the arrangement of cells in a tissue.
Without cell division, long-term tissue survival would be impossible. Inside every tissue, cells are constantly replenishing themselves through the process of division, although the rate of turnover may vary widely between different cell types in the same tissue. For example, in adult mammal brains, neurons rarely divide.
However, glial cells in the brain continue to divide throughout a mammal's adult life. Mammalian epithelial cells also turn over regularly, typically every few days. Neurons are not the only cells that lose their ability to divide as they mature. In fact, many differentiated cells lose this ability.
To help counteract this loss, tissues maintain stem cells to serve as a reservoir of undifferentiated cells. Stem cells typically have the capacity to mature into many different cell types. Transcription factors — proteins that regulate which genes are transcribed in a cell — appear to be essential to determining the pathway particular stem cells take as they differentiate.
For example, both intestinal absorptive cells and goblet cells arise from the same stem cell population, but divergent transcriptional programs cause them to mature into dramatically different cells Figure 1. Whenever stem cells are called upon to generate a particular type of cell, they undergo an asymmetric cell division.
With asymmetric division, each of the two resulting daughter cells has its own unique life course. In this case, one of the daughter cells has a finite capacity for cell division and begins to differentiate, whereas the other daughter cell remains a stem cell with unlimited proliferative ability.
Figure 1: Transcriptional regulators can act at different stages, and in different combinations, through the path of cell development and differentiation. Transcription factors can turn on at different times during cell differentiation. As cells mature and go through different stages arrows , transcription factors colored balls can act on gene expression and change the cell in different ways. This change affects the next generation of cells derived from that cell.
In subsequent generations, it is the combination of different transcription factors that can ultimately determine cell type. Although most of the tissues in adult organisms maintain a constant size, the cells that make up these tissues are constantly turning over. Therefore, in order for a particular tissue to stay the same size, its rates of cell death and cell division must remain in balance.
Character Cell Tissue Definition Cells are the smallest, structural, and functional unit of an organism. Tissues are the distinct types of material consisting of specialized cells and also types of their products. Visibility Cells are microscopic.
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