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19 de nov. de 2020 · Cell Membrane. Article PDF Available. The cell membrane. November 2020. Southern African Journal of Anaesthesia and Analgesia. DOI: 10.36303/SAJAA.2020.26.6.S3.2527. License. CC BY-NC-ND...
Chapter 4: Cell Membrane Structure and Function. Plasma Membrane: Thin barrier separating inside of cell (cytoplasm) from outside environment. Function: Isolate cell’s contents from outside environment. Regulate exchange of substances between inside and outside of cell. Communicate with other cells.
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The structure and function of cells are critically dependent on membranes, which not only separate the interior of the cell from its environment but also define the internal compartments of eukaryotic cells, including the nucleus and cytoplasmic organelles.
- Geoffrey M Cooper
- 2000
- 1.1 Introduction
- 1.2.1.2 Plasma Membrane Function
- 1.2.2 Cytoplasm and Its Organelles
- 1.2.2.1 The Endoplasmic Reticulum
- 1.2.2.2 The Golgi Complex
- 1.2.2.3 Lysosomes
- 1.2.2.5 Mitochondria
- 1.2.2.6 Ribosomes
- 1.2.3 Cytoskeleton
- 1.3.1.3 Gene Mutation
- 1.3.1.4 DNA Recombination
- 1.3.2.1 DNA Transcription
- 1.3.3 Genetic Code
- 1.4.2 Mitosis and Cytokinesis
- 1.4.4 Chromosomes and Diseases
- 1.5 Cell Transformation and Differentiation
- 1.6 Degradation of Cellular Components
- 1.6.1 Protein Turnover
- 1.6.2 Lipid Turnover
- 1.6.2.1 Cholesterol Homeostasis
- 1.7.1.1 Cell Types
- 1.7.1.2 Tissue Types
- 1.7.1.3.1 Muscle Tissue
- 1.7.1.3.2 Nerve Tissue
- Epithelial Tissue
- Indigenous Connective Tissue Cells
- 1.7.1.4.2 Immigrant Cells
- 1.7.2 Malignant Growth
- 1.7.2.1 Molecular Basis of Cancer (see also Chapter 11)
- 1.7.2.2 Tumor Angiogenesis
- 1.7.2.3 Tumor Antigens
- 1.8 Cell-to-Cell Communication
- 1.8.1 Cell-Cell Interaction
- 1.8.2 Cell Signaling and Cellular Receptors
- 1.9.2 Production of ATP
- 1.9.2.1 Glycolysis
- 1.9.2.2 Oxidative Phosphorylation
- 1.10 Transport Through the Cell Membrane
- 1.10.1.1 Diffusion
- 1.10.1.3 Active Mediated Transport
- 1.10.2 Transport by Vesicle Formation
- Transmission of Electrical Impulses
- 1.11 Cell Death
- 1.11.1 Programmed Cell Death
- 1.11.2 Accidental Cell Death
The cell is the basic unit of life in all forms of living or-ganisms, from the smallest bacterium to the most com-plex animal. On the basis of microscopic and biochemi-cal differences, living cells are divided into two major classes: prokaryotes, which include bacteria, blue-green algae, and rickettsiae, and eukaryotes, which in-clude yeasts and pl...
The water-soluble molecules such as ions, glucose, and urea only cross the membrane through transmem-brane channels, carriers, and pumps, which regulate the supply of the cell with nutrients, control internal ion concentrations, and establish a transmembrane electrical potential. Transmembrane receptors bind ex-tracellular signaling molecules such ...
Cytoplasm is an aqueous solution (cytosol) that fills the cytoplasmic matrix, the space between the nuclear en-velope and the cell membrane. The cytosol contains many dissolved proteins, electrolytes, glucose, certain lipid compounds, and thousands of enzymes. In addi-tion, glycogen granules, neutral fat globules, ribo-somes, and secretory granules...
The cytoplasm contains an interconnecting network of tubular and flat membranous vesicular structures called the endoplasmic reticulum (ER). Like the cell membrane, the walls of the ER are composed of a lipid bilayer containing many proteins and enzymes. The re-gions of ER rich in ribosomes are termed rough or granular ER, while the regions of ER w...
The Golgi complex or apparatus is a network of flat-tened smooth membranes and vesicles. It is the deliv-ery system of the cell. It collects, packages, modifies, and distributes molecules within the cell or secretes the molecules to the external environment. Within the Gol-gi bodies, the proteins and lipids synthesized by the ER are converted to gl...
Lysosomes are small vesicles (0.2–0.5 μm) formed by the Golgi complex and have a single limiting mem-brane. Lysosomes maintain an acidic matrix (pH 5 and below) and contain a group of glycoprotein digestive enzymes (hydrolases) that catalyze the rapid break-down of proteins, nucleic acids, lipids, and carbohy-drates into small basic building molecu...
Mitochondria are tubular or sausage-shaped organelles (1–3 μm). They are composed mainly of two lipid bi-layer-protein membranes. The outer membrane is smooth and derived from the ER. The inner membrane contains many infoldings or shelves called cristae which partition the mitochondrion into an inner matrix called mitosol and an outer compartment. ...
Ribosomes are large complexes of RNA and protein molecules and are normally attached to the outer sur-faces of the ER. The major function of ribosomes is to synthesize proteins. Each ribosome is composed of one large and one small subunit with a mass of several mil-lion daltons.
The cytoplasm contains a network of protein fibers, called the cytoskeleton, that provides a shape to the cell and anchors various organelles suspended in the cyto-sol. The fibers of the cytoskeleton are made up of differ-ent proteins of different sizes and shapes such as actin (actin filaments), tubulin (microtubules), and vimentin and keratin (in...
A mutation is any inherited change in the genetic mate-rial involving irreversible alterations in the sequence of DNA nucleotides. These mutations may be phenotypi-cally silent (hidden) or expressed (visible). Mutations may be classified into two categories: base substitutions and frameshift mutations. Point mutations are base substitutions involvi...
DNA can undergo important and elegant exchange events through recombination, which refers to a num-ber of distinct processes of genetic material rearrange-ment. Recombination is defined as the creation of new gene combinations and may include exchange of an en-tire chromosome or rearranging the position of a gene or a segment of a gene on a chromos...
Proteins are the tools of heredity. The essence of he-redity is the ability of the cell to use the information in its DNA to control and direct the synthesis of all pro-teins in the body. The production of RNA is called transcription and is the first stage of gene expression. The result is the formation of messenger RNA (mRNA) from the base sequenc...
The genetic code in a DNA sense strand consists of a specific nucleotide sequence coded in successive “trip-lets” that will eventually control the sequence of amino acids in a protein molecule. During transcription, a complementary code of triplets in the mRNA molecule, called codons, are synthesized. For example, the suc-cessive triplets in a DNA ...
One of the first events of mitosis takes place in the cyto-plasm. A pair of centrioles is duplicated just prior to DNA replication. Towards the end of interphase the two pairs of centrioles move to the opposite poles of the cell. The complex of microtubules (spindle) pushes the cen-trioles farther apart, creating the so-called mitotic ap-paratus. I...
Many of the processes involved in maintaining the or-ganization and equal division of chromosomes be-tween daughter cells such as DNA replication and re-pair, or mitosis and meiosis, are very complicated and can go wrong from time to time. A chromosomal dis-ease is found in situations in which defects in some as-pect of chromosome organization or b...
The zygote and blastomeres resulting from the first few cleavage divisions are totipotent, capable of forming any cell in the body. As the development progresses, certain decisions are made that narrow the develop-mental options of cells. At the point where cells become committed, a restriction event has occurred. The com-mitment of cells during cl...
The cell’s constituent proteins, lipids and RNA turn over continuously, although an individual cell can live for weeks, months, years or the entire lifetime of the or-ganism. There are three functions for this molecular degradation and replacement, constitutive, induced and macroautophagy turnovers. Constitutive turnover is a housekeeping function ...
The rate of synthesis and degradation are balanced to reach the steady-state turnover of body constituents. A protein may have specific sequences or structural con-figurations that are recognized by the proteolytic ma-chinery. There are two compartments for proteolytic activity. Lysosomes are membrane-bound protease compartments that sequester prot...
There are three classes of cellular lipids: phosphoglyce-rides, glycolipids, and cholesterol. Glycolipids, which are found in the extracellular layer of a lipid bilayer, are degraded in lysosomes. Turnover of phosphoglycerides varies in mechanism and location. Some phosphogly-cerides are degraded in lysosomes to their constituents, fatty acids, hea...
The free cholesterol is mainly found in the plasma membrane. An individual cell cannot degrade choles-terol. Cellular levels of cholesterol are regulated by a balance of endogenous synthesis, efflux of intracellular cholesterol to vascular fluids and uptake of extracellu-lar cholesterol. When present in excess, cholesterol ac-cumulates as insoluble...
The human body is an ordered clone of cells, all con-taining the same genome but specialized in different ways. There are approximately 200 different cell types that represent, for the most part, discrete and distinctly different categories based on histological and morpho-logical characteristics and cellular function. Recent, more subtle, techniqu...
In the human body, specialized cells of one or more types are organized into cooperative assemblies called tissues that perform one or more unique functions. Different types of tissue compose organs, and organs in turn are integrated to perform complex functions. The four major types of tissues are epithelial, mus-cle, connective, and nervous. Ther...
There are three types of specialized contractile cells that contain actin and myosin: smooth muscle, skeletal muscle, and cardiac muscle cells. Muscular tissue is composed of elongated cells that have the specialized function of contraction. These muscles are similar in many aspects but differ in their activation mechanisms, energy supplies and arr...
Nerve tissues develop from embryonic ectoderm in-duced to differentiate by the underlying notochord. Nerve cells, or neurons, are independent anatomic and functional units with complex morphologic character-istics. They are responsible for the reception, transmis-sion, and processing of stimuli, and the release of neu-rotransmitters and other forma...
Epithelial tissues are composed of closely aggregated polyhedral cells with very little intracellular substance. Adhesion between these cells is strong, forming cellular sheets that cover the surface of the body and line its cavities. The principal functions of epithelial tissues are covering and lining surfaces, absorption, secretion, and contract...
These cells arise in connective tissue and remain there. They include fibroblasts, fat cells, mast cells, chondro-cytes, and osteoblasts and arise from primitive mesen-chymal cells. Fibroblasts. These are spindle shaped, with oval flat-tened nuclei. They synthesize and secrete most of the macromolecules of the extracellular matrix. In re-sponse to ...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
Necrosis or accidental cell death is cell death that re-sults from irreversible injury to the cell. Cell mem-branes swell and become permeable. Lytic enzymes de-stroy the cellular contents, which then leak out into the intercellular space, leading to the mounting of an in-flammatory response (Fig. 6b). Accidental cell death occurs when cells receiv...
- Shankar Vallabhajosula, Seham Mustafa
- 2006
21 de feb. de 2020 · 3. All living cells have cell membranes (plasma membrane). Cell wall is most found in plant cells. Remove cell wall under appropriate conditions and cell lives. However. minor disruption of cell ...
The cell membrane (or plasma membrane) is a thin closed sheet that fulfils a double role: (a) morphological – delimitates the cell from its external microenvironment and confines all of its subcellular organelles; (b) functional – regulates the exchange
The cell membrane, cytoplasmic membrane or plasma membrane (a structural component of all living cells) is a living, dynamic layer that surrounds and limits the cell. It is sometimes referred to as an invisible surface layer because it is too thin to be visible with a light microscope.
