What type of macromolecule are capsules made of

For the first time, microcapsules have been prepd. The capsules were assembled using pectin, xyloglucan and cellulose in the form of cellulose nanofibers.

Such model plant cell capsules might also further improve the understanding for the digestion and release of nutrients from natural plant cells found in vegetables and fruits. Microencapsulation using biopolymers as an alternative to produce food enhanced with phytosterols and omega-3 fatty acids: A review. Food Hydrocolloids , 61 , — , DOI: Omega 3 fatty acids and phystosterols are prominent bioactive compds.

However, they are very susceptible to oxidn. Microencapsulation is being one of the most used alternatives for the purpose of protection and controlled release of these bioactive compds. Encapsulation techniques which utilize biopolymers are considered featured since they allow the formation of edible, nontoxic and easy handling materials. This review will address the methods of spray drying, ionic gelation, complexation and complex coacervation, various polymers used as wall material, the crosslinking process used together with the complex coacervation and the characterization analyzes commonly used, esp.

Finally, concluding remarks on future applications of these techniques and these bioactive compds. Cellulose biosynthesis in Acetobacter xylinum : visualization of the site of synthesis and direct measurement of the in vivo process. In vivo synthesis of cellulose by A. Cellulose is synthesized in the form of a ribbon projecting from the pole of the bacterial rod.

The obsd. Electron microscopy of the process using neg. The process of cellulose synthesis in Acetobacter is compared with that in eukaryotic plant cells. The characterization of bacterial cellulose produced by acetobacter xylinum and komgataeibacter saccharovorans under optimized fermentation conditions.

Bacterial cellulose in biomedical applications: A review. Bacterial cellulose BC derived materials represents major advances to the current regenerative and diagnostic medicine. BC is a highly pure, biocompatible and versatile material that can be utilized in several applications - individually or in the combination with different components e. The wide application and importance of BC is described by its common utilization as skin repair treatments in cases of burns, wounds and ulcers.

BC membranes accelerate the process of epithelialization and avoid infections. Furthermore, BC biocomposites exhibit the potential to regulate cell adhesion, an important characteristic to scaffolds and grafts; ultra-thin films of BC might be also utilized in the development of diagnostic sensors for its capability in immobilizing several antigens.

Therefore, the growing interest in BC derived materials establishes it as a great promise to enhance the quality and functionalities of the current generation of biomedical materials. Surface-structured bacterial cellulose with guided assembly-based biolithography gab. A powerful replica molding methodol. With this method, termed guided assembly-based biolithog. Upon bacterial fermn. Scanning electron and at. Interaction of surface-structured bacterial cellulose substrates with human fibroblasts and keratinocytes illustrates the efficient control of cellular activities which are fundamental in skin wound healing and tissue regeneration.

The deployment of surface-structured bacterial cellulose substrates in model animals as skin wound dressing or body implant further proves the high durability and low inflammatory response to the material over a period of 21 days, demonstrating beneficial effects of surface structure on skin regeneration.

Conformal bacterial cellulose coatings as lubricious surfaces. Bacterial cellulose as a raw material for food and food packaging applications. Food Syst. Nanocellulose in biomedicine: Current status and future prospect. Nanocellulose, a unique and promising natural material extd. Three different types of nanocellulose, viz.

The advancement of nanocellulose-based biomedical materials is summarized and discussed on the anal. Selected studies with significant findings are emphasized, and focused topics for nanocellulose in biomedicine research in this article include the discussion at the level of mol.

Functional modification of nanocellulose will det. Finally, future perspectives and possible research points are proposed in Section 5. The future prospects of microbial cellulose in biomedical applications.

Biomacromolecules , 8 , 1 — 12 , DOI: Czaja, Wojciech K. Malcolm , Jr. Microbial cellulose has proven to be a remarkably versatile biomaterial and can be used in wide variety of applied scientific endeavors, such as paper products, electronics, acoustics, and biomedical devices. In fact, biomedical devices recently have gained a significant amt. Due to its unique nanostructure and properties, microbial cellulose is a natural candidate for numerous medical and tissue-engineered applications.

For example, a microbial cellulose membrane has been successfully used as a wound-healing device for severely damaged skin and as a small-diam. The nonwoven ribbons of microbial cellulose microfibrils closely resemble the structure of native extracellular matrixes, suggesting that it could function as a scaffold for the prodn. In addn. In effect, microbial cellulose could function as a scaffold material for the regeneration of a wide variety of tissues, showing that it could eventually become an excellent platform technol.

If microbial cellulose can be successfully mass produced, it will eventually become a vital biomaterial and will be used in the creation of a wide variety of medical devices and consumer products. Production of hollow bacterial cellulose microspheres using microfluidics to form an injectable porous scaffold for wound healing. Healthcare Mater. Bacterial cellulose BC is a biocompatible material with high purity and robust mech.

However, the chem. In this study, a microfluidic process is developed to produce hollow BC microspheres with desirable internal structures and morphol. Microfluidics is used to generate a core-shell structured microparticle with an alginate core and agarose shell as a template to encapsulate Gluconacetobacter xylinus for long-term static culture.

The removal of the hydrogel template via thermal-chem. These hollow microspheres spontaneously assemble as functional units to form a novel injectable scaffold. In vitro, a highly porous scaffold is created to enable effective 3D cell culture with a high cell proliferation rate and better depth distribution. In vivo, this injectable scaffold facilitates tissue regeneration, resulting in rapid wound-healing in a Sprague Dawley rat skin model.

Soft bacterial cellulose microcapsules with adaptable shapes. Biomacromolecules , 20 , — , DOI: Microcapsules with controlled stability and permeability are in high demand for applications in sepn. We have developed a biointerfacial process to fabricate strong, but flexible, porous microcapsules from bacterial cellulose at an oil-water emulsion interface.

The mech. Our work provides a new approach for producing soft, permeable, and biocompatible microcapsules for substance encapsulation and protection. The capsules may offer a replacement for suspended polymer beads in com. Langmuir , 32 , — , DOI: Bahtz, Jana; Gunes, Deniz Z. Controlled mass transport is not only of importance for emulsion stability but also allows transient emulsion thickening or the controlled release of encapsulated substances, such as nutriments or simply salt.

Our prior work has shown that mass transport follows two sequential stages. In the first stage, the oil-phase structure is changed in a way that allows rapid, osmotically driven water transport in the second, osmotically dominated stage. These structural changes in the oil layer are strongly facilitated by the spontaneous formation of tiny water droplets in the oil phase, induced by the oil-sol.

This study provides a simple method based on microscopy image anal. It quant. Two different concn. Transient in situ measurement of kombucha biofilm growth and mechanical properties. Food Funct. Kombucha is a traditional beverage obtained by the fermn. The characteristic feature of kombucha is the formation of a cellulosic biofilm due to the excretion of bacterial cellulose with high purity and crystallinity.

Despite the growing industrial and technol. Here, we use interfacial shear rheol. ISR for the transient in situ detn. ISR revealed that kombucha biofilm formation is a two step process with clearly distinguishable growth phases. The first phase can be attributed to the initial adsorption of bacteria at the air-water interface and shows great variability, probably due to varying bacteria content and compn. The second phase is initiated by bacterial cellulose excretion and shows astonishing reproducibility regarding onset and final mech.

Hence, ISR qualifies as a new in situ characterization technique for kombucha biofilm growth and bacterial cellulose prodn. American Institute of Physics. An interfacial rheometer for both stress- and strain-controlled measurements of shear rheol.

The device is based on a rotating or oscillating biconical bob design in combination with a low friction electronically commutated motor system. The interfacial shear stress, viscosity, and dynamic moduli are obtained by solving the Stokes equations low Reynolds no. An improved and simple numerical method for the calcn. The scope and limitations of the rheometer are discussed. Results from steady shear and oscillatory expts. Fiji: an open-source platform for biological-image analysis.

Methods , 9 , — , DOI: Nature Publishing Group. Fiji is a distribution of the popular open-source software ImageJ focused on biol. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms.

Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biol.

Calcofluor white ST Alters the in vivo assembly of cellulose microfibrils. Science , , — , DOI: The fluorescent brightener, Calcofluor White ST I [] prevents the in vivo assembly of cryst. X-ray crystallog. I alters cellulose crystn. Synthesis of this altered product is reversible and can be monitored with fluorescence and electron microscopy.

Use of I has made it possible to sep. Fluorescence emission from mechanical pulp sheets. Regardless of its source, cellulose displayed a relatively high characteristic emission. The emission spectra of mech. Changes in emission spectra owing to bleaching or UV irradn. This suggested that, to a first approxn. Designer liquid-liquid interfaces made from transient double emulsions.

Nature communications , 9 1 , ISSN:. Current methods for generating liquid-liquid interfaces with either controlled composition or coverage often rely on adsorption equilibria which limits the freedom to design such multiphase materials, in particular when different components are used. Moreover, when interfaces become densely populated, slowing down of adsorption may impose additional constraints.

Up to now, it is not possible to control surface coverage and composition of droplet interfaces at will. Here, we report a generic and versatile method to create designer liquid-liquid interfaces, using transient double emulsions. We demonstrate how the surface coverage in Pickering emulsions can be controlled at will, even for dense particulate layers going up to multilayers.

Moreover, composite droplet interfaces with compositional control can be generated, even with particles which would have intrinsically different or even opposite adsorption characteristics. Given its simplicity, this method offers a general approach for control of composition of liquid-liquid interfaces in a variety of multiphase systems. High-throughput step emulsification for the production of functional materials using a glass microfluidic device.

Controlled massive encapsulation via tandem step emulsification in glass. Langmuir , 28 , — , DOI: Cell Press. Bacterial biofilms are complex multicellular assemblies, characterized by a heterogeneous extracellular polymeric matrix, that have emerged as hallmarks of persistent infectious diseases.

New approaches and quant. The authors performed a panel of interfacial rheol. Brewster-angle microscopy and measurements of the surface elasticity Gs' and stress-strain response provided sensitive and quant. Pellicles that formed under conditions that upregulate curli prodn. The results suggest that curli, as hydrophobic extracellular amyloid fibers, enhance the strength, viscoelasticity, and resistance to strain of E.

In-situ quantification of the interfacial rheological response of bacterial biofilms to environmental stimuli. Ruhs, Patrick A. Fredrik; Fischer, Peter. Public Library of Science. Understanding the numerous factors that can affect biofilm formation and stability remain poorly understood.

One of the major limitations is the accurate measurement of biofilm stability and cohesiveness in real-time when exposed to changing environmental conditions. Here we present a novel method to measure biofilm strength: interfacial rheol. By culturing a range of bacterial biofilms on an air-liq. We found that different bacterial species had unique viscoelastic growth profiles, which was also highly dependent on the growth media used.

We also found that we could reduce biofilm formation by the addn. Using this technique we were able to monitor changes in viscosity, elasticity and surface tension online, under const. Jump to main content. Jump to site search. You do not have JavaScript enabled. Please enable JavaScript to access the full features of the site or access our non-JavaScript page.

Issue 8, From the journal: New Journal of Chemistry. You have access to this article. Please wait while we load your content Something went wrong. Try again? Cited by. Download options Please wait Supplementary information PDF K. Article type Paper. Submitted 31 Jan Accepted 13 Mar Since procaryotes lack any intracellular organelles for processes such as respiration or photosynthesis or secretion, the plasma membrane subsumes these processes for the cell and consequently has a variety of functions in energy generation , and biosynthesis.

For example, the electron transport system that couples aerobic respiration and ATP synthesis is found in the procaryotic membrane. The photosynthetic chromophores that harvest light energy for conversion into chemical energy are located in the membrane. Hence, the plasma membrane is the site of oxidative phosphorylation and photophosphorylation in procaryotes, analogous to the functions of mitochondria and chloroplasts in eukaryotic cells.

Besides transport proteins that selectively mediate the passage of substances into and out of the cell, procaryotic membranes may contain sensing proteins that measure concentrations of molecules in the environment or binding proteins that translocate signals to genetic and metabolic machinery in the cytoplasm. Membranes also contain enzymes involved in many metabolic processes such as cell wall synthesis, septum formation, membrane synthesis, DNA replication, CO 2 fixation and ammonia oxidation.

The predominant functions of procaryotic membranes are listed in Table 7 and discussed below. Location of transport systems for specific solutes nutrients and ions. Energy generating functions, involving respiratory and photosynthetic electron transport systems, establishment of proton motive force, and transmembranous, ATP-synthesizing ATPase.

Synthesis of membrane lipids including lipopolysaccharide in Gram-negative cells. Synthesis of murein cell wall peptidoglycan.

Assembly and secretion of extracytoplasmic proteins. Coordination of DNA replication and segregation with septum formation and cell division. Chemotaxis both motility per se and sensing functions. Location of specialized enzyme system.

The cell membrane is the most dynamic structure in the cell. Its main function is as a permeability barrier that regulates the passage of substances into and out of the cell.

The plasma membrane is the definitive structure of a cell since it sequesters the molecules of life in the cytoplasm, separating it from the outside environment. The bacterial membrane freely allows passage of water and a few small uncharged molecules less than molecular weight of daltons , but it does not allow passage of larger molecules or any charged substances except when monitored by proteins in the membrane called transport systems. Transport of Solutes.

The proteins that mediate the passage of solutes through membranes are referred to variously as transport systems , carrier proteins , porters , and permeases. Transport systems operate by one of three transport processes as described below in Figure In a uniport process, a solute passes through the membrane unidirectionally.

In symport processes also called cotransport two solutes must be transported in the same direction at the same time; in antiport processes also called exchange diffusion , one solute is transported in one direction simultaneously as a second solute is transported in the opposite direction.

Transport processes in bacterial cells. Solutes enter or exit from bacterial cells by means of one of three processes: uniport, symport also called cotransport and antiport also called exchange diffusion. Transport systems Figure 23 below operate by one or another of these processes.

Bacteria have a variety of types of transport systems which can be used alternatively in various environmental situations. The elaborate development of transport processes and transport systems in procaryotes probably reflects their need to concentrate substances inside the cytoplasm against the concentration gradient of the environment.

Concentration of solutes in the cytoplasm requires the operation of an active transport system , of which there are two types in bacteria: ion driven transport systems IDT and binding-protein dependent transport systems BPDT. The definitive feature of an active transport system is the accumulation of the solute in the cytoplasm at concentrations far in excess of the environment. According to the laws of physical chemistry, this type of process requires energy.

Operation of bacterial transport systems. Bacterial transport systems are operated by transport proteins sometimes called carriers, porters or permeases in the plasma membrane.

Facilitated diffusion is a carrier-mediated system that does not require energy and does not concentrate solutes against a gradient. Active transport systems such as Ion-driven transport and Binding protein-dependent transport, use energy and concentrate molecules against a concentration gradient.

Group translocation systems, such as the phosphotransferase pts system in Escherichia coli , use energy during transport and modify the solute during its passage across the membrane.

There are four types of carrier-mediated transport systems in procaryotes. The carrier is a protein or group of proteins that functions in the passage of a small molecule from one side of a membrane to the other side. A transport system may be a single transmembranous protein that forms a channel that admits passage of a specific solute, or it may be a coordinated system of proteins that binds and sequentially passes a small molecule through the membrane.

Transport systems have the property of specificity for the solute transported. Some transport systems transport a single solute with the same specificity and kinetics as an enzyme. Some transport systems will transport structurally related molecules, although at reduced efficiency compared to their primary substrate. Most transport systems transport specific sugars, amino acids, anions or cations that are of nutritional value to the bacterium.

Facilitated diffusion systems FD are the least common type of transport system in bacteria. Actually, the glycerol uniporter in E. FD involves the passage of a specific solute through a carrier that forms a channel in the membrane. The solute can move in either direction through the membrane to the point of of equilibrium on both sides of the membrane.

Although the system is carrier-mediated and specific, no energy is expended in the transport process. For this reason the glycerol molecule cannot be accumulated against the concentration gradient. Ion driven transport systems IDT and Binding-protein dependent transport systems BPDT are active transport systems that are used for transport of most solutes by bacterial cells.

IDT systems such as the lactose permease of E. Thus the energy expended during active transport of lactose is in the form of pmf. The lactose permease is a single transmembranous polypeptide that spans the membrane seven times forming a channel that specifically admits lactose.

Two proteins form a membrane channel that allows passage of the histadine. A third protein resides in the periplasmic space where it is able to bind the amino acid and pass it to a forth protein which admits the amino acid into the membrane channel. Driving the solute through the channel involves the expenditure of energy, which is provided by the hydrolysis of ATP. Like binding protein-dependent transport systems, they are composed of several distinct components.

However, GT systems specific for one sugar may share some of their components with other group transport systems. The actual carrier in the membrane is a protein channel fairly specific for glucose. Glucose specifically enters the channel from the outside, but in order to exit into the cytoplasm, it must first be phosphorylated by the phosphotransferase system.

PEP is hydrolyzed to pyruvate and glucose is phosphorylated to form glucose-phosphate during the process. Thus, by the expenditure of a single molecule of high energy phosphate, glucose is transported and changed to glucose-phosphate.

Table 8. Generation of Energy Unlike eucaryotes, bacteria don't have intracellular organelles for energy producing processes such as respiration or photosynthesis. Instead, the cytoplasmic membrane carries out these functions.

The membrane is the location of electron transport systems ETS used to produce energy during photosynthesis and respiration, and it is the location of an enzyme called ATP synthetase ATPase which is used to synthesize ATP. Thus the outside is acidic and the inside is alkaline. Operation of the ETS also establishes a charge on the membrane called proton motive force pmf.

The outer face of the membrane becomes charged positive while inner face is charged negative, so the membrane has a positive side and a negative side, like a battery. The pmf can be used to do various types of work including the rotation of the flagellum, or active transport as described above.

The connection between electron transport, establishment of pmf, and ATP synthesis during respiration is known as oxidative phosphorylation; during photosynthesis, it is called photophorylation. Figure 24 below illustrates the membrane of E. The topographical features of the membrane from top to bottom are 1. ATPase enzyme; 7. Schematic view of the plasma membrane of Escherichia coli. The S and M rings which constitute the flagellar motor are shown.

The motor ring is imbedded in the phospholipid bilayer. It is powered by pmf to rotate the flagellar filament. The electron transport system is shown oxidizing NAD by removal of a pair of electrons, passing them through its sequence of carriers eventually to O 2. ATPase is the transmembranous protein enzyme that utilizes protons from the outside to synthesize ATP on the inside of the membrane.

Several other transmembranous proteins are transport systems which are operating by either symport or antiport processes. The plasma membrane of procaryotes may invaginate into the cytoplasm or form stacks or vesicles attached to the inner membrane surface.

These structures are sometimes referred to as mesosomes. Such internal membrane systems may be analogous to the cristae of mitochondria or the thylakoids of chloroplasts which increase the surface area of membranes to which enzymes are bound for specific enzymatic functions. The photosynthetic apparatus light harvesting pigments and ATPase of photosynthetic procaryotes is contained in these types of membranous structures.

Mesosomes may also represent specialized membrane regions involved in DNA replication and segregation, cell wall synthesis, or increased enzymatic activity. Membrane foldings and vesicles sometimes appear in electron micrographs of procaryotic cells as artifacts of preparative techniques. These membranous structures, of course, are not mesosomes, but their existence does not prove that mesosomes are not present in procaryotes, and there are several examples of procaryotic membrane topology and appearance that are suggestive of mesosomes.

There are a few antibiotics e. Biosynthetic enzymes For murein assembly e. Degradative enzymes phosphatases proteases. Detoxifying enzymes Beta-lactamases e. The cytoplasm of bacterial cells consists consists of an aqueous solution of three groups of molecules: macromolecules such as proteins enzymes , mRNA and tRNA; small molecules that are energy sources, precursors of macromolecules, metabolites or vitamins; and various inorganic ions and cofactors see Tables 9, 10, The primary structural components found in the cytoplasm are the nucleoid and ribosomes, and possibly some type of inclusion.

The cytoplasm of procaryotes is more gel-like than that of eucaryotes and the processes of cytoplasmic streaming, which are evident in eucaryotes, do not occur. Table 9. Molecular composition of E. Percentage of dry weight refers to all structural and cytoplasmic components.

Table Inorganic ions present in the cytoplasm of a growing bacterial cell. Procaryotes sometimes possess smaller extrachromosomal pieces of DNA called plasmids. The total DNA content of a procaryote is referred to as the cell genom e. The cell chromosome is the genetic control center of the cell which determines all the properties and functions of the bacterium.

During cell growth and division, the procaryotic chromosome is replicated in a semiconservative fashion to make an exact copy of the molecule for distribution to progeny cells.

However, the eucaryotic processes of meiosis and mitosis are absent in procaryotes. Replication and segregation of procaryotic DNA is coordinated by the membrane and various proteins in the cytoplasm. When a bacterium such as E. The distinct granular appearance of procaryotic cytoplasm is due to the presence and distribution of ribosomes.

Ribosomes are composed of proteins and RNA. The ribosomes of procaryotes are smaller than cytoplasmic ribosomes of eucaryotes. Procaryotic ribosomes are 70S in size, being composed of 30S and 50S subunits. The 80S ribosomes of eucaryotes are made up of 40S and 60S subunits. Ribosomes are involved in the process of translation protein synthesis , but some details of their activities differ in eucaryotes, bacteria and archaea.

The bacterial chromosome or nucleoid is the nonstaining region in the interior of the cell cytoplasm. The granular structures distributed throughout the cytoplasm are cell ribosomes. Often contained in the cytoplasm of procaryotic cells is one or another of some type of inclusion granule.

Inclusions are distinct granules that may occupy a substantial part of the cytoplasm. Inclusion granules are usually reserve materials of some sort. For example, carbon and energy reserves may be stored as glycogen a polymer of glucose or as polybetahydroxybutyric acid a type of fat granules.

Polyphosphate inclusions are reserves of PO 4 and possibly energy; elemental sulfur sulfur globules are stored by some phototrophic and some lithotrophic procaryotes as reserves of energy or electrons. Some inclusion bodies are actually membranous vesicles or intrusions into the cytoplasm which contain photosynthetic pigments or enzymes. Some inclusions in bacterial cells.

Cytoplasmic inclusions Where found Composition Function glycogen many bacteria e. Pseudomonas polymerized hydroxy butyrate reserve carbon and energy source polyphosphate volutin granules many bacteria e. Corynebacterium linear or cyclical polymers of PO4 reserve phosphate; possibly a reserve of high energy phosphate sulfur globules phototrophic purple and green sulfur bacteria and lithotrophic colorless sulfur bacteria elemental sulfur reserve of electrons reducing source in phototrophs; reserve energy source in lithotrophs gas vesicles aquatic bacteria especially cyanobacteria protein hulls or shells inflated with gases buoyancy floatation in the vertical water column parasporal crystals endospore-forming bacilli genus Bacillus protein unknown but toxic to certain insects magnetosomes certain aquatic bacteria magnetite iron oxide Fe3O4 orienting and migrating along geo- magnetic field lines carboxysomes many autotrophic bacteria enzymes for autotrophic CO2 fixation site of CO2 fixation phycobilisomes cyanobacteria phycobiliproteins light-harvesting pigments chlorosomes Green bacteria lipid and protein and bacteriochlorophyll light-harvesting pigments and antennae.

A variety of bacterial inclusions. PHB granules; b. A bacterial structure sometimes observed as an inclusion is actually a type of dormant cell called an endospore. Endospores are formed by a few groups of Bacteria as intracellular structures, but ultimately they are released as free endospores. Biologically, endospores are a fascinating type of cell.

Endospores exhibit no signs of life, being described as cryptobiotic. They are highly resistant to environmental stresses such as high temperature some endospores can be boiled for hours and retain their viability , irradiation, strong acids, disinfectants, etc. They are probably the most durable cell produced in nature. Although cryptobiotic, they retain viability indefinitely such that under appropriate environmental conditions, they germinate back into vegetative cells.

Endospores are formed by vegetative cells in response to environmental signals that indicate a limiting factor for vegetative growth, such as exhaustion of an essential nutrient.

They germinate and become vegetative cells when the environmental stress is relieved. Hence, endospore-formation is a mechanism of survival rather than a mechanism of reproduction.

Bacterial endospores. Phase microscopy of sporulating bacteria demonstrates the refractility of endospores, as well as characteristic spore shapes and locations within the mother cell. Electron micrograph of a bacterial endospore. The spore has a core wall of unique peptidoglycan surrounded by several layers, including the cortex, the spore coat and the exosporium. The dehydrated core contains the bacterial chromosome and a few ribosomes and enzymes to jump-start protein synthesis and metabolism during germination.

Tag words: bacterial structure, flagellum, flagella, pilus, pili, fimbriae, capsule, S-layer, glycocalyx, slime layer, biofilm, outer membrane, LPS, cell wall, peptidoglycan, murein, teichoic acid, plasma membrane, cell membrane, phospholipid bilayer, transport system, proton motive force, pmf, ATPase, DNA, chromosome, nucleoid, ribosome, 30S subunit, 50S subunit, 16S rRNA, inclusion, PHB, glycogen, carboxysome, endospore, parasporal crystal.

The macromolecules are made up of primary subunits such as nucleotides, amino acids and sugars Table 1. It is the sequence in which the subunits are put together in the macromolecule, called the primary structure , that determines many of the properties that the macromolecule will have.

Thus, the genetic code is determined by specific nuleotide base sequences in chromosomal DNA; the amino acid sequence in a protein determines the properties and function of the protein; and sequence of sugars in bacterial lipopolysaccharides determines unique cell wall properties for pathogens. The primary structure of a macromolecule will drive its function, and differences within the primary structure of biological macromolecules accounts for the immense diversity of life.

Table 1. Figure 1. Cutaway drawing of a typical bacterial cell illustrating structural components. See Table 2 below for chemical composition and function of the labeled components. Electron micrograph of an ultra-thin section of a dividing pair of group A streptococci 20,X.

The cell surface fimbriae fibrils are evident. The bacterial cell wall is seen as the light staining region between the fibrils and the dark staining cell interior.

Cell division in progress is indicated by the new septum formed between the two cells and by the indentation of the cell wall near the cell equator. The streptococcal cell diameter is equal to approximately one micron. TEM about 10,X. Salmonella is an enteric bacterium related to E. The enterics are motile by means of peritrichous flagella. Flagella Flagella are filamentous protein structures attached to the cell surface that provide the swimming movement for most motile procaryotes.

Figure 3. The ultrastructure of a bacterial flagellum after J. Measurements are in nanometers. The flagellum of E. The basal body and hook anchor the whip-like filament to the cell surface.

The basal body consists of four ring-shaped proteins stacked like donuts around a central rod in the cell envelope. The inner rings, associated with the plasma membrane, are the flagellar powerhouse for activating the filament.

The outer rings in the peptidoglycan and outer membrane are support rings or "bushings" for the rod. The filament rotates and contracts which propels and steers the cell during movement. Figure 4. Different arrangements of bacterial flagella. Swimming motility, powered by flagella, occurs in half the bacilli and most of the spirilla. Flagellar arrangements, which can be determined by staining and microscopic observation, may be a clue to the identity of a bacterium.