The Plant Plasma Membrane

In plant cells, the plasma membrane is a highly elaborated structure that functions as the point of exchange with adjoining cells, cell walls and the external environment. Transactions at the plasma membrane include uptake of water and essential mineral nutrients, gas exchange, movement of metabolites, transport and perception of signaling molecules, and initial responses to external biota. Selective transporters control the rates and direction of small molecule movement across the membrane barrier and manipulate the turgor that maintains plant form and drives plant cell expansion. The plasma membrane provides an environment in which molecular and macromolecular interactions are enhanced by the clustering of proteins in oligimeric complexes for more efficient retention of biosynthetic intermediates, and by the anchoring of protein complexes to promote regulatory interactions. The coupling of signal perception at the membrane surface with intracellular second messengers also involves transduction across the plasma membrane. Finally, the generation and ordering of the external cell walls involves processes mediated at the plant cell surface by the plasma membrane. This volume is divided into three sections. The first section describes the basic mechanisms that regulate all plasma membrane functions. The second describes plasma membrane transport activity. The final section of the book describes signaling interactions at the plasma membrane. These topics are given a unique treatment in this volume, as the discussions are restricted to the plasma membrane itself as much as possible. A more complete knowledge of the plasma membrane’s structure and function is essential to current efforts to increase the sustainability of agricultural production of food, fiber, and fuel crops.

The plasma membrane forms the living barrier between the cell and its surroundings. For this reason it has a wide range of important functions related to the regulation of the composition of the cell interior and to com munication with the cell exterior. The plasma membrane has therefore attracted a lot of research interest. Until the early 1970's it was only pos sible to study the plasma membrane in situ, its structure e. g. by electron microscopy and its function e. g. by uptake of radioactively labeled com pounds into the intact cell or tissue. The first isolation of plant protoplasts by enzymatic digestion of the cell wall in the early 1970's was an important step forward in that it provided direct access to the outer surface of the plasma membrane. More importantly, T. K. Hodges and R. J. Leonard in 1972 published the description of a method by which a fraction enriched in plasma membranes could be isolated from plant tissues using sucrose gradient centrifugation. As a result, the 1970's saw a leap forward in our understanding of the structurc and function of the plasma membrane. In 1981, S. Widell and C. Larsson published the first of a series of papers in which plasma membrane vesicles of high yield and purity were isolated from a wide range of plant tissues using aqueous polymer two-phase parti tioning.

In plant cells, the plasma membrane is a highly elaborated structure that functions as the point of exchange with adjoining cells, cell walls and the external environment. Transactions at the plasma membrane include uptake of water and essential mineral nutrients, gas exchange, movement of metabolites, transport and perception of signaling molecules, and initial responses to external biota. Selective transporters control the rates and direction of small molecule movement across the membrane barrier and manipulate the turgor that maintains plant form and drives plant cell expansion. The plasma membrane provides an environment in which molecular and macromolecular interactions are enhanced by the clustering of proteins in oligimeric complexes for more efficient retention of biosynthetic intermediates, and by the anchoring of protein complexes to promote regulatory interactions. The coupling of signal perception at the membrane surface with intracellular second messengers also involves transduction across the plasma membrane. Finally, the generation and ordering of the external cell walls involves processes mediated at the plant cell surface by the plasma membrane. This volume is divided into three sections. The first section describes the basic mechanisms that regulate all plasma membrane functions. The second describes plasma membrane transport activity. The final section of the book describes signaling interactions at the plasma membrane. These topics are given a unique treatment in this volume, as the discussions are restricted to the plasma membrane itself as much as possible. A more complete knowledge of the plasma membrane’s structure and function is essential to current efforts to increase the sustainability of agricultural production of food, fiber, and fuel crops.

In plant cells, the plasma membrane is a highly elaborated structure that functions as the point of exchange with adjoining cells, cell walls and the external environment. Transactions at the plasma membrane include uptake of water and essential mineral nutrients, gas exchange, movement of metabolites, transport and perception of signaling molecules, and initial responses to external biota. Selective transporters control the rates and direction of small molecule movement across the membrane barrier and manipulate the turgor that maintains plant form and drives plant cell expansion. The plasma membrane provides an environment in which molecular and macromolecular interactions are enhanced by the clustering of proteins in oligimeric complexes for more efficient retention of biosynthetic intermediates, and by the anchoring of protein complexes to promote regulatory interactions. The coupling of signal perception at the membrane surface with intracellular second messengers also involves transduction across the plasma membrane. Finally, the generation and ordering of the external cell walls involves processes mediated at the plant cell surface by the plasma membrane. This volume is divided into three sections. The first section describes the basic mechanisms that regulate all plasma membrane functions. The second describes plasma membrane transport activity. The final section of the book describes signaling interactions at the plasma membrane. These topics are given a unique treatment in this volume, as the discussions are restricted to the plasma membrane itself as much as possible. A more complete knowledge of the plasma membrane’s structure and function is essential to current efforts to increase the sustainability of agricultural production of food, fiber, and fuel crops.

Concepts of Biology is designed for the single-semester introduction to biology course for non-science majors, which for many students is their only college-level science course. As such, this course represents an important opportunity for students to develop the necessary knowledge, tools, and skills to make informed decisions as they continue with their lives. Rather than being mired down with facts and vocabulary, the typical non-science major student needs information presented in a way that is easy to read and understand. Even more importantly, the content should be meaningful. Students do much better when they understand why biology is relevant to their everyday lives. For these reasons, Concepts of Biology is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand.We also strive to show the interconnectedness of topics within this extremely broad discipline. In order to meet the needs of today's instructors and students, we maintain the overall organization and coverage found in most syllabi for this course. A strength of Concepts of Biology is that instructors can customize the book, adapting it to the approach that works best in their classroom. Concepts of Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand--and apply--key concepts.

Plant Cell Biology, Second Edition: From Astronomy to Zoology connects the fundamentals of plant anatomy, plant physiology, plant growth and development, plant taxonomy, plant biochemistry, plant molecular biology, and plant cell biology. It covers all aspects of plant cell biology without emphasizing any one plant, organelle, molecule, or technique. Although most examples are biased towards plants, basic similarities between all living eukaryotic cells (animal and plant) are recognized and used to best illustrate cell processes. This is a must-have reference for scientists with a background in plant anatomy, plant physiology, plant growth and development, plant taxonomy, and more. Includes chapter on using mutants and genetic approaches to plant cell biology research and a chapter on -omic technologies Explains the physiological underpinnings of biological processes to bring original insights relating to plants Includes examples throughout from physics, chemistry, geology, and biology to bring understanding on plant cell development, growth, chemistry and diseases Provides the essential tools for students to be able to evaluate and assess the mechanisms involved in cell growth, chromosome motion, membrane trafficking and energy exchange

The plasma membrane is at once the window through which the cell senses the environment and the portal through which the environment influences the structure and activities of the cell. Its importance in cellular physiology can thus hardly be overestimated, since constant flow of materials between cell and environment is essential to the well-being of any biological system. The nature of the materials mov ing into the cell is also critical, since some substances are required for maintenance and growth, while others, because of their toxicity, must either be rigorously excluded or permitted to enter only after chemical alteration. Such alteration frequently permits the compounds to be sequestered in special cellular compartments having different types of membranes. This type of homogeneity, plus the fact that the wear and tear of transmembrane molecular traffic compels the system to be constantly monitored and repaired, means that the membrane system of any organism must be both structurally complex and dy namic. Membranes have been traditionally difficult to study because of their fragility and small diameter. In the last several decades, however, remarkable advances have been made because of techniques permit ting the bulk isolation of membranes from homogenized cells. From such isolated membranes have come detailed physical and chemical analyses that have given us a detailed working model of membrane. We now can make intelligent guesses about the structural and func tional interactions of membrane lipids, phospholipids, proteins, sterols and water.

Plant Cell Organelles contains the proceedings of the Phytochemical Group Symposium held in London on April 10-12, 1967. Contributors explore most of the ideas concerning the structure, biochemistry, and function of the nuclei, chloroplasts, mitochondria, vacuoles, and other organelles of plant cells. This book is organized into 13 chapters and begins with an overview of the enzymology of plant cell organelles and the localization of enzymes using cytochemical techniques. The text then discusses the structure of the nuclear envelope, chromosomes, and nucleolus, along with chromosome sequestration and replication. The next chapters focus on the structure and function of the mitochondria of higher plant cells, biogenesis in yeast, carbon pathways, and energy transfer function. The book also considers the chloroplast, the endoplasmic reticulum, the Golgi bodies, and the microtubules. The final chapters discuss protein synthesis in cell organelles; polysomes in plant tissues; and lysosomes and spherosomes in plant cells. This book is a valuable source of information for postgraduate workers, although much of the material could be used in undergraduate courses.