Animal and Plant Cells
Animal and plant cells are the basic structural and functional units of living organisms. Both types of cells have a nucleus, cytoplasm, and cell membrane, but plant cells also have a cell wall and chloroplasts for photosynthesis. Animal cells are generally round and irregular in shape, while plant cells are more rectangular and have a fixed shape due to the presence of a cell wall.
8 Key excerpts on "Animal and Plant Cells"
eBook - ePub- Laurie Ann Callihan(Author)
- 2013(Publication Date)
- Research & Education Association(Publisher)
...In Figure 3–9, the organelles numbered 1 to 7 function the same way in plant cells as in animal cells (see above). 1. Golgi apparatus 2. Mitochondria 3. Rough endoplasmic reticulum 4. Ribosome 5. Nucleus 6. Nucleolus 7. Smooth endoplasmic reticulum 8. Cell walls surround plant cells. (Bacteria also have cell walls.) Cell walls are made up of cellulose and lignin, making them strong and rigid (whereas the cell membrane is relatively weak and flexible). The cell wall encloses the cell membrane, providing strength and protection for the cell. The cell wall allows plant cells to store water under relatively high concentration. The combined strength of a plant’s cell walls provides support for the whole organism. Dry wood and cork are essentially the cell walls of dead plants. The structure of the cell wall allows substances to pass through it readily, so transport in and out of the cell is still regulated by the cell membrane. 9. The cell membrane (or plasma membrane) functions in plant and animal cells in the same way. However, in some plant tissues, channels connect the cytoplasm of adjacent cells. 10. Chloroplasts are found in plant cells (and also in some protists). Chloroplasts are the site of photosynthesis within plant cells. Chlorophyll pigment molecules give the chloroplast their green color, although the chloroplasts also contain yellow and red carotenoid pigments. In the fall, as chloroplasts lose chlorophyll, these pigments are revealed, giving leaves their red and yellow colors. The body (or stroma) of the chloroplast contains embedded stacked, disk-like plates (called grana), which are the site of photosynthetic reactions. 11. The central vacuole takes up much of the volume of plant cells. It is a membrane-bound fluid-filled space, which stores water and soluble nutrients for the plant’s use. The tendency of the central vacuole to absorb water provides for the rigid shape (turgidity) of some plant cells...
eBook - ePub- Andrew Lack, David Evans(Authors)
- 2021(Publication Date)
- Taylor & Francis(Publisher)
...Section C - Plant cells C1 T HE 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...
eBook - ePubForensic Botany
Principles and Applications to Criminal Casework
- Heather Miller Coyle, Heather Miller Coyle(Authors)
- 2004(Publication Date)
- CRC Press(Publisher)
...3 Plant Cell Structure and Function HEATHER MILLER COYLE Contents 3.1 Introduction to Plant Cell Components 3.1.1 The Cell Wall 3.1.2 The Nucleus 3.1.3 Ribosomes 3.1.4 The Plasma Membrane 3.1.5 The Vacuole 3.1.6 The Cytoplasm 3.1.7 The Plastids 3.1.8 Ergastic Substances 3.1.9 Spherosomes 3.1.10 Microtubules 3.1.11 Mitochondria 3.2 Basic Plant Tissues 3.2.1 Meristem 3.2.2 Parenchyma 3.2.3 Collenchyma and Sclerenchyma 3.2.4 Xylem 3.2.5 Phloem 3.2.6 Secretory Cells 3.2.7 Epidermis 3.2.8 Periderm 3.3 Common Staining Techniques and Laboratory Exercises 3.3.1 Epidermis 3.3.2 Trichomes 3.3.3 Periderm 3.3.4 Collenchyma 3.3.5 Sclerenchyma 3.4 Summary General. References 3.1 Introduction to Plant Cell Components Essential to the identification and classification of a plant for recognition of value as evidence, one must know the parts of a plant and features that can aid in identification. This chapter focuses on the internal composition of a plant cell and how plant cells are organized into organs to serve specific functions essential to plant life. Plants and animals do not appear similar when comparing whole organisms; however, at the cellular level they are remarkably alike. The commonality of Animal and Plant Cells argues for a common ancient ancestral cell type that has, over the course of evolutionary time, evolved into the more specialized Animal and Plant Cells that we recognize. The cellular structure of a plant cell as observed under light microscopy contains a cell wall, a nucleus, a plasma membrane, a central vacuole, cytoplasm, plastids and specialized plastid types, and often starch grains and crystals (see Figure 3.1). Cellular organelles can be observed easily with the use of inexpensive stains and light microscopy, or with transmission and scanning electron microscope techniques. 3.1.1 The Cell Wall Cell walls provide support for the plant and offer protection to the cell. Cellulose fibers and jelly-like pectin comprise the primary plant cell wall...
eBook - ePub- 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...
eBook - ePub- Charles Adams, Mike Early, Jane Brook, Katherine Bamford(Authors)
- 2014(Publication Date)
- Routledge(Publisher)
...In this way, the nucleus transmits instructions for the assembly of chemicals within the cell. The coded information for these processes is found in genes within the chromosomes. ▶ The mitochondria release energy, in a controlled way, by the process of respiration (see p. 116). The meristems of the stem, root and flower, for example, have cells which are packed with mitochondria in order to supply energy for rapid cell division in these areas. ▶ Chloroplasts, containing the pigment chlorophyll, are involved in the production of sugar by the process of photosynthesis (see p. 112) and in its short-term storage in the form of starch. Starch grains are often found in the chloroplasts and throughout the cytoplasm in living cells. ▶ The endoplasmic reticulum is a complex mesh of membranes that enables transport of chemicals within and between cells and links with the cell membrane at the cell surface. Specialized units made of RNA and protein called ribosomes are commonly located on the endoplasmic reticulum and manufacture proteins, including enzymes which speed up chemical processes. ▶ The vacuole is a sac within the cell, bound by a membrane which contains dilute sugar, nutrients, pigments and waste materials. It may occupy the major volume of the cell and its main functions are storage of waste products and maintaining cell shape through controlling cell turgor (see p. 120), which is important for support in herbaceous plants in particular. The whole of the living matter of a cell, its membrane, nucleus and cytoplasm, is collectively called protoplasm. Plant cells differ from animal cells in having a cell wall, a vacuole and chloroplasts. Plant tissues The tissues which make up the structure of a plant can be grouped into five categories according to the functions they perform. Meristematic tissues are where new cells are produced by cell division...
eBook - ePub- Bryan G. Bowes, James D. Mauseth(Authors)
- 2008(Publication Date)
- CRC Press(Publisher)
...The thin external primary wall is delimited from the protoplast by the membranous plasmalemma. Several large organelles are present including the nucleus, several vacuoles, and a number of chloroplasts. Normally under the light microscope (LM), only the wall and these larger organelles would be apparent (47, 62). However, with the greater resolution of the transmission electron microscope (TEM), mitochondria, endoplasmic reticulum, dictyosomes, ribosomes, microtubules, and plasmodesmata are also distinguishable (61). Most of these organelles are membrane-bounded (51, 55, 59 – 61, 63). In this chapter, only the fine structural features of plant cells are considered, whereas the histological structure of differentiated cells and tissues is discussed in Chapter 3. CELL MEMBRANES Substances located exterior to the plasmalemma, or in the cytosol surrounding membrane-bounded organelles (51, 61), cannot mix freely with the materials localized internally because these membranes are semi-permeable. Membranes consist of a lipid bilayer (63), with the interspersed proteins and complexes forming the molecular pumps, enzymes, and other structural components. Most proteins are large and project onto the surface of the membrane (63 – 65). Differing types of organelles normally remain discrete within the cell since their membranes vary somewhat in individual structure. The plasmalemma (59, 60, 63) and the membranes of mature dictyosome cisternae and vesicles (55, 66) are generally the thickest membranes of the cell and measure about 10 nm wide. When viewed in transverse section (in chemically fixed material), membranes usually show a tripartite appearance (48, 66, 67); but in freeze-fractured specimens the plasmalemma (64, 65) and other membranes (68, 69) show numerous particles which are protein complexes (63). The plasmalemma adjacent to the plant cell wall sometimes reveals hexagonal arrays of particles which are possibly the sites of cellulose microfibrillar synthesis (63)...
eBook - ePubCancer
Basic Science and Clinical Aspects
- Craig A. Almeida, Sheila A. Barry(Authors)
- 2011(Publication Date)
- Wiley-Blackwell(Publisher)
...As a result, life processes would not occur. What distinguishes living organisms from nonliving things? Why is it important that a membrane be semipermeable? What are some characteristics of a plasma membrane that allow for this property? Figure 2.1 The human body consists of seven hierarchal levels of organization. (a) Atoms combine to form (b) molecules, which combine to form (c) cells that work together to form (d) tissues, that work together to form (e) organs, that work together to form (f) organ systems, that work together to form an (g) organism. Table 2.1 A range of cells and their sizes Category Cell type Size Smallest cell Microplasma (bacterium) 0.1 micrometer (μm) or 0.000004 inch Smallest human cell Sperm 3 μm or 0.0001 inch Largest human cell Egg 35 μm in diameter or 0.0014 inch in diameter Longest cell Nerves Over 3 meters long! or over 9.84 feet long! There is a wide variety of cells in the body and each type has its own distinct shape, chemical composition, and internal structures that enable it to carry out its unique function. For example, red blood cells (RBCs) are small and packed with hemoglobin, a protein that has an ability to bind oxygen (Figure 2.2a). 2.2 The small size of red blood cells (RBCs) enables them to easily pass through the smallest of blood vessels while their unique round, biconcave (i.e., dimpled on both sides), disc shape provides a large outer surface area that dramatically increases the efficiency of both oxygen pick-up in the lungs and oxygen delivery to the body’s tissues. Cells in the outer layer of our skin, the epidermis, are flattened and tightly packed together so as to create a barrier between the environment and the internal tissues of the body (Figure 2.2b). Nerve cells have many long extensions called dendrites and axons that extend outward from the central cell body...
eBook - ePub- Julian Coleman, David Evans, Anne Kearns(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...Chapter 2 Basic plant biology for cell culture 1. Tissues and organs Before considering the practical aspects of plant tissue culture, it is important to be aware of the way in which plants grow and develop. Their unique growth form, in which discrete areas of cell division remain active throughout the life of the plant, contrasts markedly with animal development. Understanding the zones of cell division and the way in which their activity is initiated and regulated helps to put into context the principles and methods of plant cell and tissue culture. Plants show a wide diversity of form and vary in the number and types of organs they possess. The major groups of organs, leaves, roots and stems are present in most plants (although all may be very highly modified). Flowers, fruit and storage organs, like tubers, formed at specific stages in the plant’s life cycle, also show a variety of forms. Organs may be cultured intact (organ culture) or divided to initiate callus (an undifferentiated cell mass) that can differentiate to form organs and embryos. Sections of leaf, for instance, are often used as the host tissue for genetic transformation and embryos are regenerated from the transgenic tissue. 2. Plant tissues Plants consist of specialized cell types with differing functions. Plant organs are made of three types of tissue: dermal tissue (the epidermis or outer cell layer), vascular tissue (the transport system of the plant) and ground tissues (all the remaining cells). The type and quantity of each tissue varies for each organ. 2.1 Ground tissues Ground tissues lie under the epidermis and contribute to structural strength and function. Parenchyma cells are the most abundant cells found throughout the plant and form the bulk of organs like leaves, roots and stems. They have thin flexible cell walls and are initially cuboid, later becoming nearly spherical or cylindrical. In mature tissue, their shape is constrained by surrounding cells...
