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69-450: A grandstand is a normally permanent structure for seating spectators, typically at sports stadiums and including both auto racing and horse racing . The grandstand is in essence like a single section of a stadium , but differs from a stadium in that it does not wrap all or most of the way around. Grandstands may have basic bench seating, but usually have individual chairs like a stadium. Grandstands are also usually covered with

138-417: A bioink for 3D bioprinting and biofabrication of 3D tissue models. The collagen protein is composed of a triple helix, which generally consists of two identical chains (α1) and an additional chain that differs slightly in its chemical composition (α2). The amino acid composition of collagen is atypical for proteins, particularly with respect to its high hydroxyproline content. The most common motifs in

207-404: A collagen helix . The collagen helix is mostly found in connective tissue such as cartilage , bones , tendons , ligaments , and skin . Vitamin C is vital for collagen synthesis, while Vitamin E improves its production. Depending upon the degree of mineralization , collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen

276-415: A hierarchical organization , but hierarchy makes it easier for a listener to understand and remember the music. In analogy to linguistic terminology, motifs and phrases can be combined to make complete musical ideas such as sentences and phrases . A larger form is known as the period . One such form that was widely used between 1600 and 1900 has two phrases, an antecedent and a consequent , with

345-417: A pointer that links them together in a particular order. Out of these any number of other data structures can be created such as stacks , queues , trees and hash tables . In solving a problem, a data structure is generally an integral part of the algorithm . In modern programming style, algorithms and data structures are encapsulated together in an abstract data type . Software architecture

414-460: A roof , but are open on the front. They are often multi-tiered. Grandstands are found at places like Epsom Downs Racecourse and Atlanta Motor Speedway . They may also be found at fairgrounds , circuses , and outdoor arenas used for rodeos . In the United States , smaller stands are called bleachers , and are usually far more basic and typically single-tiered (hence the difference from

483-701: A "grand stand"). Early baseball games were often staged at fairgrounds, and the term "grandstand" came along when standalone baseball parks began to be built. A covered bleacher may be called a " pavilion ", also to distinguish from the main "grandstand". The term grandstanding , from the notion of playing to the people in the grandstands, is often used as a pejorative to describe someone intent on drawing attention to themself. Structure Buildings , aircraft , skeletons , anthills , beaver dams , bridges and salt domes are all examples of load -bearing structures. The results of construction are divided into buildings and non-building structures , and make up

552-516: A cell. The formation of collagen which results in fibrillary collagen (most common form) is discussed here. Meshwork collagen, which is often involved in the formation of filtration systems, is another common form of collagen. All types of collagens are triple helices, and the differences lie in the make-up of their alpha peptides created in step 2. Collagen has an unusual amino acid composition and sequence: Cortisol stimulates degradation of (skin) collagen into amino acids. Most collagen forms in

621-506: A crystal have a structure that involves repetition of a basic unit called a unit cell . The atoms can be modeled as points on a lattice , and one can explore the effect of symmetry operations that include rotations about a point, reflections about a symmetry planes, and translations (movements of all the points by the same amount). Each crystal has a finite group, called the space group , of such operations that map it onto itself; there are 230 possible space groups. By Neumann's law ,

690-404: A different secondary structure to the normal collagen polyproline II (PPII) of random coils . This process describes the formation of gelatin , which is used in many foods, including flavored gelatin desserts . Besides food, gelatin has been used in pharmaceutical, cosmetic, and photography industries. It is also used as a dietary supplement , and has been advertised as a potential remedy against

759-404: A half cadence in the middle and a full cadence at the end providing punctuation. On a larger scale are single-movement forms such as the sonata form and the contrapuntal form , and multi-movement forms such as the symphony . A social structure is a pattern of relationships. They are social organizations of individuals in various life situations. Structures are applicable to people in how

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828-445: A lower Young's modulus compared to fibrils. When studying the mechanical properties of collagen, tendon is often chosen as the ideal material because it is close to a pure and aligned collagen structure. However, at the macro, tissue scale, the vast number of structures that collagen fibers and fibrils can be arranged into results in highly variable properties. For example, tendon has primarily parallel fibers, whereas skin consists of

897-442: A moving display of blood and muscle, enabling methods of cardiac imaging technology to arrive at ratios essentially stating blood in ( cardiac input ) and blood out ( cardiac output ). Pathology of the collagen underpinning of the heart is understood within the category of connective tissue disease . As the skeleton forms the structure of the body, it is vital that it maintains its strength, even after breaks and injuries. Collagen

966-457: A multilevel hierarchy of structures employing biominerals and proteins , at the bottom of which are collagen fibrils . In biology , one of the properties of life is its highly ordered structure, which can be observed at multiple levels such as in cells , tissues , organs , and organisms . In another context, structure can also observed in macromolecules , particularly proteins and nucleic acids . The function of these molecules

1035-568: A mutation in type 1 collagen , dominant autosomal disorder, results in weak bones and irregular connective tissue, some cases can be mild while others can be lethal. Mild cases have lowered levels of collagen type 1 while severe cases have structural defects in collagen. Chondrodysplasias – Skeletal disorder believed to be caused by a mutation in type 2 collagen , further research is being conducted to confirm this. Ehlers–Danlos syndrome – Thirteen different types of this disorder, which lead to deformities in connective tissue, are known. Some of

1104-413: A net of wavy fibers, resulting in a much higher strength and lower ductility in tendon compared to skin. The mechanical properties of collagen at multiple hierarchical levels is given. Collagen is known to be a viscoelastic solid. When the collagen fiber is modeled as two Kelvin-Voigt models in series, each consisting of a spring and a dashpot in parallel, the strain in the fiber can be modeled according to

1173-475: A parallel, staggered array. 40 nm gaps between the ends of the tropocollagen subunits (approximately equal to the gap region) probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is hydroxylapatite (approximately) Ca 10 (OH) 2 (PO 4 ) 6 . Type I collagen gives bone its tensile strength . Collagen-related diseases most commonly arise from genetic defects or nutritional deficiencies that affect

1242-454: A redundant structure is needed so that if a component fails it has backups. A high redundancy is an essential part of the design of several systems in the Space Shuttle . As a branch of philosophy, logic is concerned with distinguishing good arguments from poor ones. A chief concern is with the structure of arguments. An argument consists of one or more premises from which a conclusion

1311-428: A regular structure at the molecular level was presented in the mid-1930s. Research then concentrated on the conformation of the collagen monomer , producing several competing models, although correctly dealing with the conformation of each individual peptide chain. The triple-helical "Madras" model, proposed by G. N. Ramachandran in 1955, provided an accurate model of quaternary structure in collagen. This model

1380-424: A similar manner, but the following process is typical for type I: A single collagen molecule, tropocollagen, is used to make up larger collagen aggregates, such as fibrils. It is approximately 300  nm long and 1.5 nm in diameter, and it is made up of three polypeptide strands (called alpha peptides, see step 2), each of which has the conformation of a left-handed helix – this should not be confused with

1449-434: A society is as a system organized by a characteristic pattern of relationships. This is known as the social organization of the group. Sociologists have studied the changing structure of these groups. Structure and agency are two confronted theories about human behaviour. The debate surrounding the influence of structure and agency on human thought is one of the central issues in sociology. In this context, agency refers to

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1518-471: A variety of diagrams called structural formulas . Lewis structures use a dot notation to represent the valence electrons for an atom; these are the electrons that determine the role of the atom in chemical reactions. Bonds between atoms can be represented by lines with one line for each pair of electrons that is shared. In a simplified version of such a diagram, called a skeletal formula , only carbon-carbon bonds and functional groups are shown. Atoms in

1587-408: Is inferred . The steps in this inference can be expressed in a formal way and their structure analyzed. Two basic types of inference are deduction and induction . In a valid deduction, the conclusion necessarily follows from the premises, regardless of whether they are true or not. An invalid deduction contains some error in the analysis. An inductive argument claims that if the premises are true,

1656-508: Is interdigitated with its neighboring microfibrils to a degree that might suggest they are individually unstable, although within collagen fibrils, they are so well ordered as to be crystalline. A distinctive feature of collagen is the regular arrangement of amino acids in each of the three chains of these collagen subunits. The sequence often follows the pattern Gly - Pro -X or Gly-X- Hyp , where X may be any of various other amino acid residues. Proline or hydroxyproline constitute about 1/6 of

1725-421: Is a part containing five molecules in cross-section, called the "overlap", and a part containing only four molecules, called the "gap". These overlap and gap regions are retained as microfibrils assemble into fibrils, and are thus viewable using electron microscopy. The triple helical tropocollagens in the microfibrils are arranged in a quasihexagonal packing pattern. There is some covalent crosslinking within

1794-403: Is also abundant in corneas , blood vessels , the gut , intervertebral discs , and the dentin in teeth. In muscle tissue , it serves as a major component of the endomysium . Collagen constitutes 1% to 2% of muscle tissue and accounts for 6% of the weight to skeletal muscle . The fibroblast is the most common cell creating collagen in a body. Gelatin , which is used in food and industry,

1863-474: Is collagen that was irreversibly hydrolyzed using heat, basic solutions, or weak acids. The name collagen comes from the Greek κόλλα ( kólla ), meaning " glue ", and suffix -γέν, -gen , denoting "producing". Over 90% of the collagen in the human body is type I & III collagen . However, as of 2011, 28 types of human collagen have been identified, described, and divided into several groups according to

1932-434: Is determined by their shape as well as their composition, and their structure has multiple levels. Protein structure has a four-level hierarchy. The primary structure is the sequence of amino acids that make it up. It has a peptide backbone made up of a repeated sequence of a nitrogen and two carbon atoms. The secondary structure consists of repeated patterns determined by hydrogen bonding . The two basic types are

2001-402: Is effective. There's minimal evidence supporting collagen's benefits for hair and nails. Overall, the effectiveness of oral collagen supplements is not well-proven, and focusing on a healthy lifestyle and proven skincare methods like sun protection is recommended. The molecular and packing structures of collagen eluded scientists over decades of research. The first evidence that it possesses

2070-437: Is fibrillar strain, and ε T is total strain. Collagen has a wide variety of applications, from food to medical. In the medical industry, it is used in cosmetic surgery and burn surgery . In the food sector, one use example is in casings for sausages . If collagen is subject to sufficient denaturation , such as by heating, the three tropocollagen strands separate partially or completely into globular domains, containing

2139-437: Is layered in variable densities with smooth muscle mass. The mass, distribution, age, and density of collagen all contribute to the compliance required to move blood back and forth. Individual cardiac valvular leaflets are folded into shape by specialized collagen under variable pressure . Gradual calcium deposition within collagen occurs as a natural function of aging. Calcified points within collagen matrices show contrast in

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2208-475: Is made available to the wound bed, closure can occur. Wound deterioration, followed sometimes by procedures such as amputation, can thus be avoided. Collagen is a natural product and is thus used as a natural wound dressing and has properties that artificial wound dressings do not have. It is resistant against bacteria, which is of vital importance in a wound dressing. It helps to keep the wound sterile, because of its natural ability to fight infection. When collagen

2277-405: Is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins , such as enzymes . Tough bundles of collagen called collagen fibers are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great tensile strength , and

2346-411: Is the main component of fascia , cartilage , ligaments , tendons , bone and skin. Along with elastin and soft keratin , it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging . It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It may be one of

2415-489: Is the specific choices made between possible alternatives within a framework. For example, a framework might require a database and the architecture would specify the type and manufacturer of the database. The structure of software is the way in which it is partitioned into interrelated components. A key structural issue is minimizing dependencies between these components. This makes it possible to change one component without requiring changes in others. The purpose of structure

2484-632: Is then modified by the addition of hydroxyl groups to the amino acids proline and lysine . This step is important for later glycosylation and the formation of a triple helix structure to collagen. Because the hydroxylase enzymes performing these reactions require vitamin C as a cofactor , a long-term deficiency in this vitamin results in impaired collagen synthesis and scurvy . These hydroxylation reactions are catalyzed by two different enzymes: prolyl 4-hydroxylase and lysyl hydroxylase . The reaction consumes one ascorbate molecule per hydroxylation. The synthesis of collagen occurs inside and outside of

2553-420: Is to optimise for (brevity, readability, traceability, isolation and encapsulation, maintainability, extensibility, performance and efficiency), examples being: language choice , code , functions , libraries , builds , system evolution , or diagrams for flow logic and design . Structural elements reflect the requirements of the application: for example, if the system requires a high fault tolerance, then

2622-402: Is used as a burn dressing, healthy granulation tissue is able to form very quickly over the burn, helping it to heal rapidly. Throughout the four phases of wound healing, collagen performs the following functions: Collagen is used in laboratory studies for cell culture , studying cell behavior and cellular interactions with the extracellular environment . Collagen is also widely used as

2691-821: Is used in bone grafting as it has a triple helical structure, making it a very strong molecule. It is ideal for use in bones, as it does not compromise the structural integrity of the skeleton. The triple helical structure of collagen prevents it from being broken down by enzymes, it enables adhesiveness of cells and it is important for the proper assembly of the extracellular matrix. Collagen scaffolds are used in tissue regeneration, whether in sponges, thin sheets, gels, or fibers. Collagen has favorable properties for tissue regeneration, such as pore structure, permeability, hydrophilicity, and stability in vivo. Collagen scaffolds also support deposition of cells, such as osteoblasts and fibroblasts , and once inserted, facilitate growth to proceed normally. Collagens are widely employed in

2760-612: Is widely used in dermal fillers for aesthetic correction of wrinkles and skin aging. Collagen cremes are also widely sold even though collagen cannot penetrate the skin because its fibers are too large. Collagen is a vital protein in skin , hair , nails , and other tissues. Its production decreases with age and factors like sun damage and smoking . Collagen supplements, derived from sources like fish and cattle , are marketed to improve skin, hair, and nails. Studies show some skin benefits, but these supplements often contain other beneficial ingredients, making it unclear if collagen alone

2829-492: The Young's modulus of collagen at the molecular level. Only above a certain strain rate is there a strong relationship between elastic modulus and strain rate, possibly due to the large number of atoms in a collagen molecule. The length of the molecule is also important, where longer molecules have lower tensile strengths than shorter ones due to short molecules having a large proportion of hydrogen bonds being broken and reformed. On

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2898-399: The extracellular spaces of tissues. Additional assembly of fibrils is guided by fibroblasts, which deposit fully formed fibrils from fibripositors. In the fibrillar collagens, molecules are staggered to adjacent molecules by about 67  nm (a unit that is referred to as 'D' and changes depending upon the hydration state of the aggregate). In each D-period repeat of the microfibril, there

2967-442: The fibrillar scale, collagen has a lower modulus compared to the molecular scale, and varies depending on geometry, scale of observation, deformation state, and hydration level. By increasing the crosslink density from zero to 3 per molecule, the maximum stress the fibril can support increases from 0.5 GPa to 6 GPa. Limited tests have been done on the tensile strength of the collagen fiber, but generally it has been shown to have

3036-648: The infrastructure of a human society. Built structures are broadly divided by their varying design approaches and standards, into categories including building structures, architectural structures , civil engineering structures and mechanical structures. The effects of loads on physical structures are determined through structural analysis , which is one of the tasks of structural engineering . The structural elements can be classified as one-dimensional ( ropes , struts , beams , arches ), two-dimensional ( membranes , plates, slab , shells , vaults ), or three-dimensional (solid masses). Three-dimensional elements were

3105-568: The interventricular septum and the atrioventricular septum . Collagen contribution to the measure of cardiac performance summarily represents a continuous torsional force opposed to the fluid mechanics of blood pressure emitted from the heart. The collagenous structure that divides the upper chambers of the heart from the lower chambers is an impermeable membrane that excludes both blood and electrical impulses through typical physiological means. With support from collagen, atrial fibrillation never deteriorates to ventricular fibrillation . Collagen

3174-415: The α-helix and the β-pleated sheet . The tertiary structure is a back and forth bending of the polypeptide chain, and the quaternary structure is the way that tertiary units come together and interact. Structural biology is concerned with biomolecular structure of macromolecules. Chemical structure refers to both molecular geometry and electronic structure. The structure can be represented by

3243-409: The ageing process. From the Greek for glue, kolla , the word collagen means " glue producer" and refers to the early process of boiling the skin and sinews of horses and other animals to obtain glue. Collagen adhesive was used by Egyptians about 4,000 years ago, and Native Americans used it in bows about 1,500 years ago. The oldest glue in the world, carbon-dated as more than 8,000 years old,

3312-434: The amino acid sequence of collagen are glycine - proline -X and glycine-X-hydroxyproline, where X is any amino acid other than glycine, proline or hydroxyproline. The average amino acid composition for fish and mammal skin is given. First, a three-dimensional stranded structure is assembled with amino acids glycine and proline as its principal components. This is not yet collagen but is its precursor: procollagen. Procollagen

3381-433: The biosynthesis, assembly, posttranslational modification, secretion, or other processes involved in normal collagen production. In addition to the above-mentioned disorders, excessive deposition of collagen occurs in scleroderma . One thousand mutations have been identified in 12 out of more than 20 types of collagen. These mutations can lead to various diseases at the tissue level. Osteogenesis imperfecta – Caused by

3450-741: The childhood or adolescent years. Knobloch syndrome – Caused by a mutation in the COL18A1 gene that codes for the production of collagen XVIII. Patients present with protrusion of the brain tissue and degeneration of the retina; an individual who has family members with the disorder is at an increased risk of developing it themselves since there is a hereditary link. When not synthesized, collagen can be harvested from animal skin. This has led to deforestation as has occurred in Paraguay where large collagen producers buy large amounts of cattle hides from regions that have been clear-cut for cattle grazing. Collagen

3519-659: The collagen fibers within the molecule, facilitating hydrogen bonding and the formation of intermolecular cross-links. This kind of regular repetition and high glycine content is found in only a few other fibrous proteins, such as silk fibroin . Collagen is not only a structural protein. Due to its key role in the determination of cell phenotype, cell adhesion, tissue regulation, and infrastructure, many sections of its non-proline-rich regions have cell or matrix association/regulation roles. The relatively high content of proline and hydroxyproline rings, with their geometrically constrained carboxyl and (secondary) amino groups, along with

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3588-442: The conclusion is likely. Collagen Collagen ( / ˈ k ɒ l ə dʒ ə n / ) is the main structural protein in the extracellular matrix of a body's various connective tissues . As the main component of connective tissue, it is the most abundant protein in mammals. 25% to 35% of a mammalian body's protein content is collagen. Amino acids are bound together to form a triple helix of elongated fibril known as

3657-467: The construction of artificial skin substitutes used in the management of severe burns and wounds. These collagens may be derived from bovine, equine, porcine, or even human sources; and are sometimes used in combination with silicones , glycosaminoglycans , fibroblasts, growth factors and other substances. Collagen is one of the body's key natural resources and a component of skin tissue that can benefit all stages of wound healing . When collagen

3726-530: The following equation: d ϵ D d ϵ T = α + ( β − α ) e x p [ − γ ϵ T ϵ T ˙ ] {\displaystyle {\frac {d\epsilon _{D}}{d\epsilon _{T}}}=\alpha +(\beta -\alpha )exp[-\gamma {\frac {\epsilon _{T}}{\dot {\epsilon _{T}}}}]} where α, β, and γ are defined materials properties, ε D

3795-661: The individual human capacity to act independently and make free choices. Structure here refers to factors such as social class , religion , gender , ethnicity , customs, etc. that seem to limit or influence individual opportunities. In computer science , a data structure is a way of organizing information in a computer so that it can be used efficiently. Data structures are built out of two basic types: An array has an index that can be used for immediate access to any data item (some programming languages require array size to be initialized ). A linked list can be reorganized, grown or shrunk, but its elements must be accessed with

3864-555: The interior (axis) of the helix, where there is no space for a larger side group than glycine's single hydrogen atom. For the same reason, the rings of the Pro and Hyp must point outward. These two amino acids help stabilize the triple helix – Hyp even more so than Pro; a lower concentration of them is required in animals such as fish, whose body temperatures are lower than most warm-blooded animals. Lower proline and hydroxyproline contents are characteristic of cold-water, but not warm-water fish;

3933-517: The latter tend to have similar proline and hydroxyproline contents to mammals. The lower proline and hydroxyproline contents of cold-water fish and other poikilotherm animals leads to their collagen having a lower thermal stability than mammalian collagen. This lower thermal stability means that gelatin derived from fish collagen is not suitable for many food and industrial applications. The tropocollagen subunits spontaneously self-assemble , with regularly staggered ends, into even larger arrays in

4002-996: The main option available to early structures such as Chichen Itza . A one-dimensional element has one dimension much larger than the other two, so the other dimensions can be neglected in calculations; however, the ratio of the smaller dimensions and the composition can determine the flexural and compressive stiffness of the element. Two-dimensional elements with a thin third dimension have little of either but can resist biaxial traction. The structure elements are combined in structural systems . The majority of everyday load-bearing structures are section-active structures like frames, which are primarily composed of one-dimensional (bending) structures. Other types are Vector-active structures such as trusses , surface-active structures such as shells and folded plates, form-active structures such as cable or membrane structures, and hybrid structures. Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from

4071-477: The most abundant proteins in the fossil record, given that it appears to fossilize frequently, even in bones from the Mesozoic and Paleozoic . Collagen is a complex hierarchical material with mechanical properties that vary significantly across different scales. On the molecular scale, atomistic and course-grained modeling simulations, as well as numerous experimental methods, have led to several estimates of

4140-480: The rarer types can be lethal, leading to the rupture of arteries. Each syndrome is caused by a different mutation. For example, the vascular type (vEDS) of this disorder is caused by a mutation in collagen type 3 . Alport syndrome – Can be passed on genetically, usually as X-linked dominant, but also as both an autosomal dominant and autosomal recessive disorder, those with the condition have problems with their kidneys and eyes, loss of hearing can also develop during

4209-413: The rich abundance of glycine, accounts for the tendency of the individual polypeptide strands to form left-handed helices spontaneously, without any intrachain hydrogen bonding. Because glycine is the smallest amino acid with no side chain, it plays a unique role in fibrous structural proteins. In collagen, Gly is required at every third position because the assembly of the triple helix puts this residue at

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4278-414: The right-handed alpha helix . These three left-handed helices are twisted together into a right-handed triple helix or "super helix", a cooperative quaternary structure stabilized by many hydrogen bonds . With type I collagen and possibly all fibrillar collagens, if not all collagens, each triple-helix associates into a right-handed super-super-coil referred to as the collagen microfibril. Each microfibril

4347-409: The structure they form. All of the types contain at least one triple helix . The number of types shows collagen's diverse functionality. The five most common types are: The collagenous cardiac skeleton which includes the four heart valve rings, is histologically, elastically and uniquely bound to cardiac muscle. The cardiac skeleton also includes the separating septa of the heart chambers –

4416-557: The symmetry of a crystal determines what physical properties, including piezoelectricity and ferromagnetism , the crystal can have. A large part of numerical analysis involves identifying and interpreting the structure of musical works. Structure can be found at the level of part of a work, the entire work, or a group of works. Elements of music such as pitch , duration and timbre combine into small elements like motifs and phrases , and these in turn combine in larger structures. Not all music (for example, that of John Cage ) has

4485-427: The total sequence. With glycine accounting for the 1/3 of the sequence, this means approximately half of the collagen sequence is not glycine, proline or hydroxyproline, a fact often missed due to the distraction of the unusual GX 1 X 2 character of collagen alpha-peptides. The high glycine content of collagen is important with respect to stabilization of the collagen helix as this allows the very close association of

4554-435: The triple helices and a variable amount of covalent crosslinking between tropocollagen helices forming well-organized aggregates (such as fibrils). Larger fibrillar bundles are formed with the aid of several different classes of proteins (including different collagen types), glycoproteins, and proteoglycans to form the different types of mature tissues from alternate combinations of the same key players. Collagen's insolubility

4623-678: The way in which collagen structure affects cell–cell and cell–matrix communication and how tissues are constructed in growth and repair and changed in development and disease. For example, using AFM–based nanoindentation it has been shown that a single collagen fibril is a heterogeneous material along its axial direction with significantly different mechanical properties in its gap and overlap regions, correlating with its different molecular organizations in these two regions. Collagen fibrils/aggregates are arranged in different combinations and concentrations in various tissues to provide varying tissue properties. In bone, entire collagen triple helices lie in

4692-466: Was a barrier to the study of monomeric collagen until it was found that tropocollagen from young animals can be extracted because it is not yet fully crosslinked . However, advances in microscopy techniques (i.e. electron microscopy (EM) and atomic force microscopy (AFM)) and X-ray diffraction have enabled researchers to obtain increasingly detailed images of collagen structure in situ . These later advances are particularly important to better understanding

4761-848: Was found to be collagen – used as a protective lining on rope baskets and embroidered fabrics , to hold utensils together, and in crisscross decorations on human skulls . Collagen normally converts to gelatin, but survived due to dry conditions. Animal glues are thermoplastic , softening again upon reheating, so they are still used in making musical instruments such as fine violins and guitars, which may have to be reopened for repairs – an application incompatible with tough, synthetic plastic adhesives, which are permanent. Animal sinews and skins, including leather, have been used to make useful articles for millennia. Gelatin- resorcinol - formaldehyde glue (and with formaldehyde replaced by less-toxic pentanedial and ethanedial ) has been used to repair experimental incisions in rabbit lungs . Bovine collagen

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