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An Archimedean spiral is, for example, generated while coiling a carpet. [6] A hyperbolic spiral appears as image of a helix with a special central projection (see diagram). A hyperbolic spiral is some times called reciproke spiral, because it is the image of an Archimedean spiral with a circle-inversion (see below). [7]
Greater diversity in chloroplast shapes exists among the algae, which often contain a single chloroplast [12] that can be shaped like a net (e.g., Oedogonium), [105] a cup (e.g., Chlamydomonas), [106] a ribbon-like spiral around the edges of the cell (e.g., Spirogyra), [107] or slightly twisted bands at the cell edges (e.g., Sirogonium). [108]
[14] α-helices are formed by hydrogen bonding of the backbone to form a spiral shape (refer to figure on the right). [12] The β pleated sheet is a structure that forms with the backbone bending over itself to form the hydrogen bonds (as displayed in the figure to the left).
Some common shapes of simple molecules include: Linear: In a linear model, atoms are connected in a straight line. The bond angles are set at 180°. For example, carbon dioxide and nitric oxide have a linear molecular shape. Trigonal planar: Molecules with the trigonal planar shape are somewhat triangular and in one plane (flat). Consequently ...
Secondary structure [4] [5] α-Helices Cylindrical spiral ribbons, with ribbon plane approximately following plane of peptides. β-Strands Arrows with thickness, about one-quarter as thick as they are wide, showing direction and twist of the strand from amino to carboxy end. β-sheets are seen as unified because neighboring strands twist in unison.
Compared to B-DNA, the A-DNA form is a wider right-handed spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form occurs under non-physiological conditions in partly dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA and RNA strands, and in enzyme-DNA complexes.
You can keep your children safer by knowing the symbols and codes pedophiles use to recognize and communicate with each other.
Deviation (having the opposite form) could be found in a small number of chemical compounds, or certain organ or behavior but that variation strictly depends upon the genetic make up of the organism. From chemical level (molecular scale), biological systems show extreme stereospecificity in synthesis, uptake, sensing, metabolic processing.