2.4: Chapter Summary
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A cell i s the smallest unit of a living thing. Whether comprised of one cell (like bacteria) or many cells (like a plant), we call it an organism. Thus, cells are the basic building blocks of all organisms. Eukaryotic cells are generally around 10 to 100 μm in size. As a cell increases in size, its surface area-to-volume ratio decreases, decreasing the efficiency of transport. If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume. All cells contain these same four components: 1. plasma (cell) membrane , 2. cytoplasm and the fluid region, cytosol , 3. DNA, and 4. ribosomes . Eukaryotic cells contain organelles and a membrane-bound nucleus that is attached to an endomembrane system. The main structures that comprise the endomembrane system are the endoplasmic reticulum , vesicles , and the Golgi body . Furthermore, eukaryotic cells contain cytoskeleton and a mitochondria . Plant cells contain some structures animal cells don't possess: a cell wall , central vacuole , peroxisomes , and plastids , most notably chloroplasts . The mitochondria and chloroplast have evolved via the Endosymbiosis Theory .
Several plant cells of one kind that interconnect with each other and perform a shared function form tissues. Plant tissue systems fall into one of two general types: meristematic tissue , and permanent (or non-meristematic) tissue. Dermal tissue covers the plant and can be found on the outer layer of roots, stems and leaves. Vascular tissue is the plumbing system of the plant. It allows water, minerals, and dissolved sugars from photosynthesis to pass through roots, stems, leaves, and other parts of the plant. It is primary composed of two types of conducting tissue: xylem and phloem . Tissues that are not considered dermal or vascular tissue are noted as ground tissue . These cells store molecules (such as starch), photosynthesize (such as mesophyll cells), or support the plant. Ground tissue is often divided into three cell types: collenchyma , sclerenchyma , and parenchyma .
After completing this chapter, you should be able to...
- Describe the role of cells in organisms.
- Summarize cell theory.
- Address the significance of cell size.
- Describe the structures that all cells share in common.
- State the role of the plasma membrane.
- Describe the structures of eukaryotic cells.
- Summarize the functions of the major cell organelles.
- Describe the difference between meristematic and non-meristematic tissues.
- Compare and contrast dermal, ground, and vascular tissue.
Attribution
Curated and authored by Kammy Algiers using 4.1 Studying Cells and 4.3 Eukaryotic cells from Biology 2e by OpenStax (licensed CC-BY ). Access for free at openstax.org .