A structure is an arrangement and organization of interrelated elements in a material object or
system , or the object or system so organized. [1] Material structures include man-made objects such as buildings and machines and natural objects such as biological organisms , minerals and chemicals . Abstract structures include data structures in computer science and musical form . Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many links , or a lattice featuring connections between components that are neighbors in space.
The structure of a DNA molecule is essential to its function.
Load-bearing
A traditional Sami food storage structure
Gothic quadripartite cross-ribbed vaults of the Saint-Séverin church in Paris
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 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). [2] :2 The latter was 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. [2] :2–3
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. [3]
:134–136
Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from a multilevel hierarchy of structures employing biominerals and proteins , at the bottom of which are collagen fibrils. [4]
Biological
Ribbon schematic of the 3D structure of the protein
triosephosphate isomerase. The brown spirals are α-helices and the green arrows are β strands, the components of β-pleated sheets.
Main article: Biological organisation
In biology, structures exist at all levels of organization, ranging hierarchically from the
atomic and molecular to the cellular, tissue ,
organ , organismic , population and ecosystem level. Usually, a higher-level structure is composed of multiple copies of a lower-level structure.
Structural biology is concerned with the
biomolecular structure of macromolecules , particularly proteins and nucleic acids. [5] The function of these molecules 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 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.