Plant Cell Organelles

12 Key excerpts on "Plant Cell Organelles"

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  eBook - PDF

  Introduction to Plant Anatomy

  • Gurnah, Akinloye(Authors)
  • 2018(Publication Date)
  • Agri Horti Press

    (Publisher)

  • Lysosomes : These organelles digest food by breaking down larger molecules into smaller ones, using special proteins. • Cytoplasm : It helps in maintaining the cell shape. Along with this, it plays an important role in the internal movement of cell organelles, cell mobility and muscle fibre contraction. It also distributes oxygen and nutrients to different parts of the cell. • Nucleolus : It is the most prominent structure in the nucleus wherein ribosomes are made. • Vacuole : The plant cell contains a large, single vacuole (an enclosed compartment) which is used to store water, compounds and minerals that help in plant growth. • Ribosomes : These are packets of RNA (Ribonucleic Acid) and are called as protein builders or synthesizers of the cell. • Chloroplasts : They are the food producers of the cell, containing chlorophyll, the green pigment essential for photosynthesis. Their main function is to generate sugars and starches. • Nucleus : It’s the most important part of the cell, comprising chromosomes, i.e. structures made up of genetic information that helps in cell growth and reproduction. Read more on cell nucleus: structure and functions. This ebook is exclusively for this university only. Cannot be resold/distributed. Plant Cell Organelles 77 • Nuclear Envelope : It’s an enclosure that surrounds nucleus and its contents. Unlike cell membrane which has pores and spaces for RNA and proteins to pass through, it keeps the chromatin and nucleolus inside the nucleus. • Smooth Endoplasmic Reticulum : It’s main function is to package proteins for transport, synthesize membrane phosolipids, and secrete calcium. It also performs transformation of bile pigments, glycogenolysis (the breakdown of glycogen), and detoxification of different drugs and chemical agents. • Mitochondria : It provides energy to the cell by combining sugar molecules with oxygen to generate carbon dioxide and water.

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  Plant Biochemistry

  • Caroline Bowsher, Alyson Tobin(Authors)
  • 2021(Publication Date)
  • Garland Science

    (Publisher)

  3 Plant Cell Structure Key Concepts The internal organization of plant cells is dependent on membranes. Membranes, which consist of lipids and proteins, depend on a water phase for their organization into two-dimensional sheets. Proteins are targeted to specific membranes and confer specific properties on the membrane, including its permeability to solutes. The plasma membrane defines the outer boundary of the cell, regulates solute exchange, and participates in cell wall formation. Vacuoles can occupy a very large proportion of cell space in vegetative tissues and store a variety of compounds, including pigments, proteins, and osmotically active solutes. The endomembrane system consists of two distinct compartments: the endoplasmic reticulum and the Golgi. It provides a complex internal space bounded by a membrane that is involved in the synthesis of proteins, polysaccharides, and lipids, mostly destined for export from the cell. Cell walls act as mechanical supports and osmoregulators and define the shape of each cell, ultimately defining the shape of the whole plant. Cell walls regulate the flux of molecules between cells and provide transport pathways within the plant. In common with other eukaryotic cells, most plant cells contain nuclei, which are concerned with the storage and expression of genetic information; mitochondria, which are mostly involved in respiration; and peroxisomes, which have diverse roles in plants. Plastids are a defining feature of plant cells and are specialized for a variety of functions, notably photosynthesis in all green tissues. Plant Organs and Tissues Consist of Communities of Cells The previous chapter (Chapter 2) emphasized the importance of plant cell structure in the biochemical functioning of the whole plant. It is the unique challenges plants face as sessile organisms that need to, for example, harvest solar energy, acquire inorganic mineral elements, cope with loss of water, etc., that determine their cell structure

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  eBook - ePub

  Functional Biology of Plants

  • Martin J. Hodson, John A. Bryant(Authors)
  • 2012(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Chapter 2 Introduction to Plant Cells

  The previous chapter described the emergence in evolution of the angiosperms, the flowering plants. Much of the rest of this book deals with angiosperm function at the levels of organ and whole organism; we discuss the integration of growth and development, the angiosperm life cycle and the inter-organism interactions involved in various angiosperm lifestyles.

  However, in order to understand the plant as a functioning organism, it is necessary to have some knowledge of plant biology at the cellular and sub-cellular levels. Therefore, in this chapter and the next, we provide introductions to plant cells and to the major molecular activities in which the cells participate.

  2.1 Plant Cells

  There is a sense in which there is no such thing as a ‘typical’ plant cell. Cell structure varies extensively according to the function of the cell in question. Nevertheless, it is helpful at this point to consider the main features of plant cells before looking at those features in more detail in subsequent sections. The features are illustrated diagrammatically in Figure 2.1 .

  Figure 2.1 Diagram of a plant cell.

  Author: Mariana Ruiz. http://en.wikipedia.org/wiki/File:Plant_cell_structure_svg.svg

  First, plant cells are characterized by being contained within a cell wall (section 2.2), composed mostly of polysaccharides and whose structure varies according to cell age and function. Inside the cell wall is the cell's outer membrane, the plasma membrane (section 2.3). In older cells, the next most obvious feature is the cell vacuole (section 2.8), a large aqueous space bounded by another membrane, the tonoplast. The vacuole's main functions are storage of particular solutes and the sequestration of hydrolytic enzymes. In vacuolated cells, the cytosol or cytoplasm is confined to a narrow zone between the vacuole and the plasma membrane (Figure 2.1

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  Cambridge O Level Biology 5090

  • Azhar ul Haque Sario(Author)
  • 2023(Publication Date)
  • tredition

    (Publisher)

  Golgi Apparatus: Functioning as a cellular post office, it modifies, sorts, and packages proteins and lipids for secretion or for use within the cell. It's crucial for the transport of lipids around the cell and the creation of lysosomes.

  Plasma Membrane: This is the cell's security guard, controlling the movement of substances in and out of the cell. It’s selectively permeable and maintains the cell's internal environment.

  Cytoskeleton: This network of fibers gives the cell shape and support, and is involved in various types of cell movement. It includes structures like microfilaments, intermediate filaments, and microtubules.

  Plant Cells: Nature's Solar Panels Cell Wall: Unlike animal cells, plant cells have a rigid cell wall made of cellulose. This provides structural support, protects against mechanical stress, and gives the cell its shape.

  Chloroplasts: Unique to plant cells, these organelles carry out photosynthesis, converting solar energy into chemical energy stored in ATP and NADPH. They contain the green pigment chlorophyll, which absorbs light energy.

  Central Vacuole: Occupying a significant portion of the cell's volume, the vacuole stores nutrients and waste products. It plays a key role in maintaining turgor pressure against the cell wall, which is crucial for structural support and plant rigidity.

  Plasmodesmata: These are channels between plant cells that allow for transport and communication between them, crucial for the movement of water, nutrients, and small molecules. Golgi Apparatus, ER, and Mitochondria: Similar to those in animal cells, these structures perform comparable functions in protein and lipid synthesis, energy production, and cellular transport. Bacterial Cells: Masters of Adaptation

  Cell Wall and Membrane: Bacterial cells have a protective cell wall that offers structural support and shapes the cell. The plasma membrane beneath it performs similar functions as in eukaryotic cells, controlling the entry and exit of substances.

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  eBook - ePub

  Principles of Plant Genetics and Breeding

  • George Acquaah(Author)
  • 2020(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  A eukaryote may also be structurally organized at various levels of complexity: whole organism, organs, tissues, cells, organelles, and molecules, in this order of descending complexity. Plant breeding of sexually reproducing species by conventional tools is usually conducted at the whole plant level by crossing selected parents. Flowers are the units for crossing. The progeny of the cross is evaluated to select those with the desired combination of parental traits. The use of molecular tools allows plant breeders to directly manipulate the DNA, the hereditary material, and thereby circumvent the sexual process. Also, other biotechnological tools (e.g. tissue culture, cell culture, protoplast culture) enable genetic manipulation to be made below the whole plant level.

  S1.3 The plant cell and tissue

  The plant cell consists of several organelles and structures with distinct as well as interrelated functions (Table S1.1 ). Some organelles occur only in plants while others occur only in animals. The nucleus is the most prominent organelle in the cell. The extranuclear region is called the cytoplasm. For the plant breeder, the organelles of special interest are those directly associated with plant heredity, as discussed next.

  Table S1.1

  A summary of the structures of plant cells and their functions.

  Plasma membrane	This differentially permeable cell boundary delimits the cell from its immediate external environment. The surface of the cell may contain specific receptor molecules and may elicit an immune response.
  Nucleus	It contains DNA and proteins that are condensed in strands called chromosomes (called chromatin when uncoiled).
  Cytoplasm	The part of the cell excluding the nucleus and enclosed by the plasma membrane. It is made up of a colloidal material called cytosol and contains various organelles.
  Endoplasmic reticulum	A membranous structure of two kinds – smooth (no ribosomes) and rough (has ribosomes). It increases the surface area for biochemical synthesis.
  Ribosomes	Organelles that contain RNA and are the sites of protein synthesis.
  Mitochondria	Organelles that are the sites of respiration; they contain DNA.
  Chloroplasts	Contain DNA and chlorophyll; they are sites of photosynthesis.
  Cell wall	A rigid boundary outside the plasma membrane.
  Golgi apparatus	Also called dictyosomes. It has a role in cell wall formation.

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  eBook - ePub

  BIOS Instant Notes in Plant Biology

  • Andrew Lack, David Evans(Authors)
  • 2021(Publication Date)
  • Taylor & Francis

    (Publisher)

  Section C - Plant cells

  C1   THE PLANT CELL

  Key Notes

  Cell structure

  The plant cell has a cell wall and plasma membrane enclosing the cytoplasm. Organelles, bounded by membranes, occur within the cytoplasm and are supported and moved by the cytoskeleton. The nucleus contains DNA and nucleoli. Many plant cells have a large vacuole.

  Cell membranes

  The endomembrane system of the cell is involved in synthesis and transport. The nucleus is surrounded by a nuclear envelope. The endoplasmic reticulum (ER) is divided into perinuclear ER and cortical ER, and may be smooth or rough (coated with ribosomes). Material from the ER is modified and sorted in the Golgi apparatus (GA) from which it travels in vesicles to the plasma membrane or the vacuole.

  Organelles of metabolism

  Mitochondria generate adenosine triphosphate (ATP) from stored food reserves. Chloroplasts carry out photosynthesis. Microbodies include peroxisomes containing catalase and glyoxysomes containing enzymes of lipid biosynthesis.

  The cell wall

  The cell wall is a dynamic, metabolic structure made up predominantly of carbohydrate. Adjoining cells are interconnected by plasmodesmata, in which membranes bridge the wall. Everything within the plasma membrane is the symplast; outside it is the apoplast, which is a water-permeated space, in which hydrophilic molecules are dissolved.

  Related topics

  The cell wall (C2) Nucleus and genome (C5) Cell division (C6) Membranes (C4) Plastids and mitochondria (C3)

  Cell structure

  Plant cells show a wide range of shapes and internal structures, depending on their function.

  Figure 1

  illustrates the key features of a typical plant cell. Other cells, such as reproductive cells and conducting cells may be very different in appearance. It consists of a cell wall in close contact with a plasma membrane surrounding the cytoplasm, which is made up of aqueous fluid cytosol and many organelles. These organelles are supported and moved by a meshwork of fine protein filaments, the cytoskeleton, which includes microtubules made up of the protein tubulin and microfibrils made up of the protein actin. The nucleus contains genetic information in chromosomes and nucleoli that contain machinery for the production of ribosomes

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  eBook - PDF

  Color Atlas of Biochemistry

  • Jan Koolman, Klaus-Heinrich Röhm(Authors)
  • 2012(Publication Date)
  • Thieme

    (Publisher)

  Probably the most im-portant organelles in the cell’s metabolism are the mitochondria, which are around the same size as bacteria (p. 206). The lysosomes (p. 224) and peroxisomes (p. 226) are small, globular organelles that carry out specific tasks. The whole cell is traversed by a framework of pro-teins known as the cytoskeleton (p. 198ff.). In addition to these organelles, plant cells also have plastids—e.g., chloroplasts in which pho-tosynthesis takes place. In the interior of plant cells, there is a large, fluid-filled vacuole . Like bacteria and fungi, plant cells have a rigid cell wall consisting of polysaccharides and pro-teins. The cytoplasm is the part of the cell between the plasma membrane and nucleus. When the plasma membrane is removed by gentle treat-ment with detergents or shear forces , the or-ganelles can be obtained by stepwise centrifu-gation. The remaining clear solution is called the cytosol . Structure of Cells 195 A. Comparison of prokaryotes and eukaryotes Prokaryotes Eukaryotes Eubacteria Archaebacteria Single-celled Fungi Plants Animals Single or multi cellular Missing Present, complicated, specialized DNA RNA: Synthesis and maturation Protein: Synthesis and maturation Metabolism Endocytosis and Exocytosis Small, circular, no introns, plasmids Large, in nucleus, many introns Simple, in cytoplasm Complicated, in nucleus Simple, coupled with RNA synthesis Complicated, in the cytoplasm and the rough endoplasmic reticulum Anaerobic or aerobic very flexible Mostly aerobic, compartmented No Yes Organisms 1–10 µ m Form Organelles, cytoskeleton, cell division apparatus 10–100 µ m Number per cell 10–30 µ m Golgi apparatus 6% 1 Endoplasmic reticulum 9% 1 Mitochondrion 22% ~ 2000 Peroxisome 1% 400 Nucleus 6% 1 Lysosome 1% 300 Free ribosomes Endosome 1% 200 Cytoplasm 54% 1 Plasma membrane Proportion of cell volume B. Structure of an animal cell

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  eBook - ePub

  Biomedical Applications

  • Malgorzata Lekka, Daniel Navajas, Manfred Radmacher, Alessandro Podestà, Malgorzata Lekka, Daniel Navajas, Manfred Radmacher, Alessandro Podestà(Authors)
  • 2023(Publication Date)
  • De Gruyter

    (Publisher)

  In bacteria, all cellular processes are carried out within a single cell body. In multicellular organisms, different kinds of cells perform different functions. Cells embedded within their microenvironment (the extracellular matrix, or ECM) assemble in highly specialized tissues (connective, muscle, nervous, and epithelial) as the basis for organ formation. Despite the high level of cellular specialization, most of the animal cells possess similar cellular structures (Figure 4.1.1). Figure 4.1.1: Schematic structure of an animal cell. A major component of the cell is the nucleus. The nucleus is a highly specialized organelle that contains genetic information encoded in DNA strands. It is surrounded by a double-layer phospholipidic membrane (called the nuclear envelope) that separates it from other regions present inside the cells. The nuclear membrane contains holes (called nuclear pores) that regulate the passage of molecules to and from the nucleus. A semifluid matrix found inside the nucleus is called nucleoplasm. Within it, most of the nuclear material consists of chromatin, the less condensed form of the cell’s DNA that organizes to form chromosomes during mitosis or cell division. The nucleus also contains one or more nucleoli, which are membraneless organelles that manufacture ribosomes – the cell’s protein-producing structures. Close to the cell nucleus, an endoplasmic reticulum with associated ribosomes is located. This organelle is responsible for protein and lipid synthesis. Newly synthesized proteins and lipids are sorted in the Golgi apparatus, from which they are distributed to other cellular compartments or membranes. The mitochondria are organelles where energy is stored. They contain two major membranes: the outer and the inner membranes. The inner membrane has restricted permeability, and it is loaded with proteins involved in electron transport and ATP (adenosine triphosphate) synthesis, used for energy production

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  eBook - ePub

  Introduction to Molecular Biophysics

  • Jack A. Tuszynski, Michal Kurzynski(Authors)
  • 2003(Publication Date)
  • CRC Press

    (Publisher)

  Spreading throughout the cytoplasm is the endoplasmic reticulum (ER). It is a folded system of membranes that loop back and forth to provide a large surface area. The ER provides a surface area for cell reactions. It is also the site of lipid production. The two forms of ER are (1) smooth ER which has no associated ribosomes and (2) rough ER that has attached ribosomes to give it texture. The ribosomes manufacture proteins for the cell. Listed below are the remaining key organelles.

  The Golgi apparatus is responsible for packaging proteins for cells. Once the proteins are produced by rough ER, they pass into the sack-like cisternae that constitute the main part of the Golgi body. The proteins are then squeezed into “blebs” that drift off into the cytoplasm.

  Lysosomes are also called suicide sacks. They are produced by the Golgi bodies and consist of single membranes surrounding powerful digestive enzymes.

  Animal cells generally contain centrioles , as discussed above. Cilia and flagella are found in many different life forms. Plant cells generally contain storage vacuoles, cell walls , and plastids . Vacuoles are large empty-appearing areas in the cytoplasm. They are usually found in plant cells where they store waste. As plant cells age, they grow larger and occupy most of the cytoplasm in mature cells. Cell walls are the rigid structures surrounding plant cells. They provide support.

  Plastids are large organelles found in plants and some protists but not in animals or fungi. They can easily be seem through a light microscope. Chloroplasts represent one group of plastids called chromoplasts (colored plastids). The other class is designated leucoplasts (colorless plastids); they usually store food molecules. Included in this group are amyloplasts or starch plastids present, for example, in potato root cells.

  Finally, contractile vacuoles are organelles that are critical in enabling protozoa to combat the effects of osmosis. Protozoa must constantly excrete the water that enters through their membranes.

  4.11 Nucleus: nuclear chromatin, chromosomes, and nuclear lamina

  The cell nucleus

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  Basic Biology

  • Khushboo Chaudhary, Pankaj Kumar Saraswat(Authors)
  • 2023(Publication Date)
  • Delve Publishing

    (Publisher)

  Endoplasmic Reticulum It is two types • Rough ER: with ribosomes. • Smooth ER: with no visible ribosomes. • Golgi apparatus: Sorts proteins made by the ribosomes and sends them to needed places in the cell. • Lysosomes- Organelles that are filled with digestive enzymes to remove waste and invading bacteria. Mitochondria: It referred to as the “powerhouse” of the cell release energy for the cell. It converts the energy stored in glucose into ATP for the cell. Basic Biology 156 Vacuoles are fluid which filled organelles enclosed by a membrane. It is store materials such as food, sugar, water, and waste products. Eukaryotic plant cell Plant cells are also eukaryotic cells, but plant cells contain some organelles that are not found in animal cells. Plant Cell Organelles Cell wall It is a rigid wall outside the plasma membrane. It provides the cell with extra support. Chloroplasts It captures light and energy; and converts it into chemical energy. Chlorophyll It is the green pigment found inside the chloroplast. Plastids The organelles that store things such as food in the plant cell. 21. CELL ORGANELLE PLASMA MEMBRANE, ENDOPLASMIC RETICULUM, MITOCHONDRIA, CYTOSKELETON, NUCLEUS AND GOLGI APPARATUS. Introduction The basic structural and functional unit of life. The smallest units that display the characteristics of life, i.e. reproduction, metabolism, response to stimuli. Plasma membrane is selectively permeable boundary between the cell and the environment. Nucleus is regulatory center of the cell. Cytoplasm is everything between the plasma membrane and the nucleus (fluid + organelles). Cell Biology 157 Plasma Membrane Structure is phospholipd bilayer with proteins embedded in, and attached to, the inner (intracellular) and outer (extracellular) surfaces. Function • Selectively permeable barrier: controls what enters and leaves the cell.

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  Plant Biochemistry

  • James Bonner, Joseph E. Varner(Authors)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  L. (1972a). / . Cell Biol. 54, 507-539. Witman, G. B., Carlson, K., and Rosenbaum, J. L. (1972b). J. Cell Biol. 54, 540-555. Wooding, F. B. P., and Northcote, D. H. (1964). J. Cell Biol. 23, 327-337. This page intentionally left blank 8 Vacuoles Ph. ΜΑΤΙ LE I. Introduction 189 II. Biochemistry of Vacuoles 190 A. Experimental Approaches 190 Β. Vacuolar Enzymes 194 C. Substances Deposited in Vacuoles 199 III. Functions of Vacuoles 204 A. Lysosomal Function 204 B. Accumulation and Mobilization 211 C. Turgor 217 IV. Ontogeny of the Vacuome 219 General References 221 References 222 I. Introduction Plant cells are subdivided into several morphologically distinct compartments that are separated from one another by membranes. The vacuome (all the vacuoles present in a cell) is certainly one of the most conspicuous of these compartments. It is by far the most voluminous compartment in parenchyma cells. It is distinguished by its physical properties. Early plant cytologists (see Kuster, 1951) conceived of vacuoles as watery regions separated by semipermeable membranes from the jellylike, colloidal cytoplasm. This membrane is known as the tonoplast because it is held in tension by the osmotic properties of the vacuolar fluid, the cell sap. Vacuoles are ubiquitous in the plant kingdom, yet they vary widely in size, shape, number per cell, and even color. They are always sur-rounded by a simple unit membrane, a property shared with other organelles (such as peroxisomes, or constituents of the Golgi complex). The identification of an organelle as a vacuole requires certification by several criteria. Classic French cytology used the accumulation of basic vital stains, such as neutral red, for the identification of vacuoles 190 Ph. MATILE (see Dangeard, 1956). This criterion recognizes that the vacuole often accumulates organic acids and phenolic compounds capable of binding basic stains.

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  The Cell

  • Britannica Educational Publishing, Kara Rogers(Authors)
  • 2010(Publication Date)
  • Britannica Educational Publishing

    (Publisher)

  CHAPTER 3Cellular Organelles

  A cell with its many different DNA, RNA, and protein molecules is quite different from a test tube containing the same components. When a cell is dissolved in a test tube, thousands of different types of molecules randomly mix together. In the living cell, however, these components are kept in specific places, reflecting the high degree of organization essential for the growth and division of the cell. Maintaining this internal organization requires a continuous input of energy, because spontaneous chemical reactions always create disorganization. Thus, much of the energy released by ATP hydrolysis fuels processes that organize macromolecules inside the cell.

  THE RELATIVE VOLUMES OCCUPIEDBY SOME CELLULAR COMPARTMENTSIN A TYPICAL LIVER CELL

  When a eukaryotic cell is examined at high magnification in an electron microscope, it becomes apparent that specific membrane-bound organelles divide the interior into a variety of subcompartments. Although not detectable in the electron microscope, it is clear from biochemical assays that each organelle contains a different set of macromolecules. This biochemical segregation reflects the functional specialization of each compartment. Thus, the mitochondria, which produce most of the cell’s ATP, contain all of the enzymes needed to carry out the tricarboxylic acid cycle and oxidative phosphorylation. Similarly, the degradative enzymes needed for the intracellular digestion of unwanted macromolecules are confined to the lysosomes.

  It is clear from this functional segregation that the many different proteins specified by the genes in the cell nucleus must be transported to the compartment where they will be used. Not surprisingly, the cell contains an extensive membrane-bound system devoted to maintaining just this intracellular order. The system serves as a post office, guaranteeing the proper routing of newly synthesized macromolecules to their proper destinations.

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