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In structural biology, resolution can be broken down into 4 groups: (1) sub-atomic, when information about the electron density is obtained and quantum effects can be studied, (2) atomic, individual atoms are visible and an accurate three-dimensional model can be constructed, (3) helical, secondary structure, such as alpha helices and beta sheets; RNA helices (in ribosomes), (4) domain, no ...
Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a conventional transmission electron microscope (TEM) when viewing biological specimens such as cells ...
Structural biology deals with structural analysis of living material (formed, composed of, and/or maintained and refined by living cells) at every level of organization. [ 1 ] Early structural biologists throughout the 19th and early 20th centuries were primarily only able to study structures to the limit of the naked eye's visual acuity and ...
The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.
By using ingenious procedures for the analysis of periodic arrays of biological macromolecules, in which data from low-dose electron images and diffraction patterns were combined, Henderson and Unwin (1975) reconstructed a three-dimensional image of purple membranes at 0.7 nm resolution. Glucose embedding was employed to alleviate dehydration ...
Optical resolution of cellular structures in the range of about 50 nm can be achieved, even in label-free cells, using localization microscopy SPDM. By using two different laser wavelengths, SPDM reveals cellular objects which are not detectable under conventional fluorescence wide-field imaging conditions, beside making for a substantial ...
The two pathways for homologous recombination in eukaryotes, showing the formation and resolution of Holliday junctions. The Holliday junction is a key intermediate in homologous recombination, a biological process that increases genetic diversity by shifting genes between two chromosomes, as well as site-specific recombination events involving integrases.
Cell Biology in "The Biology Project" of University of Arizona. Centre of the Cell online; The Image & Video Library of The American Society for Cell Biology Archived 2011-06-10 at the Wayback Machine, a collection of peer-reviewed still images, video clips and digital books that illustrate the structure, function and biology of the cell.