Computer-generated model three-dimensional

Computer-generated model of the quaternary structure of hemoglobin, a protein consisting of four interlinked polypeptide chains, each shown in a different color. Computers are important tools for the study of biomolecules, as they help scientists visualize complex three-dimensional structures. 

FIGURE 10.6 A tetrapeptide inhibitor of a bacterial serine protease is seen here as a stick model fitted to its corresponding difference electron density generated by computer graphics. The three-dimensional mesh representation for the density is clearly an advance over the multiple, two-dimensional density sections in terms of fine detail. 

FIGURE 10.7 Computer graphics systems now allow rapid adjustment of molecular models to fit the electron density generated as three-dimensional mesh images. Two segments of polypeptide chain... 

Stereochemistry deals with the three-dimensional arrangement of a molecule s atoms, and we have attempted to show stereochemistry with wedge-and-dash drawings and computer-generated models. It is possible, however, to convey stereochemical information in an abbreviated form using a method devised by the German chemist Emil Fischer. 

Computer-generated model of a section of a mitochondrion from chicken brain, based on a three-dimensional electron tomogram. [I Frey and C. Mannella, 2000, Trends Biochem. Sci. 25 319.]... 

Computer-Generated Models The students ability to understand the geometry and three-dimensional structure of molecules is essential to the understanding of organic and biochemical reactions. Computergenerated models are used throughout the text because they are both accurate and easily visualized. 

Figure 4. Computer generated model of the three-dimensional structure of Mb. The amino acids essential for the binding of three of the monoclonal antibodies are shown. The amino acids and the antibodies correspond as follows Green, clone 3.4 orange, clone 1 purple, clone 5. The heme group is shown in red.

Uncertainty in modeling lies in the fact that a three-dimensional model can either support a structural hypothesis or can be the result of modeling artifacts. Computer modeling is subject to imprecision in the low resolution data, subjectivity in the generation of three-dimensional models, and uncertainty in the formation of structural hypotheses. The theory of possibility, based on fuzzy logic, is used to classify structural hypotheses according to their likelihood to contain multiple-sequence data consistent conformations based upon the sequence-structure relation, R. 

Computer-generated models need significant development if they will ever be able to predict the detail of this three-dimensional lace-work. 

Years ago plastic scale models were fabricated for each plant under construction, providing excellent three-dimensional representations of the actual facilities. Today, in the age of the microcomputer, it is quicker, easier, and much cheaper to generate models by means of computer graphics. 

This process uses a moving laser beam, directed by a computer, to prepare the model. The model is made up of layers having thicknesses about 0.005-0.020 in. (0.012-0.50 mm) that are polymerized into a solid product. Advanced techniques also provides fast manufacturing of precision molds (152). An example is the MIT three-dimensional printing (3DP) in which a 3-D metal mold (die, etc.) is created layer by layer using powdered metal (300- or 400-series stainless steel, tool steel, bronze, nickel alloys, titanium, etc.). Each layer is inkjet-printed with a plastic binder. The print head generates and deposits micron-sized droplets of a proprietary water-based plastic that binds the powder together. 

AIM theory provides a physical basis for the theory of Lewis electron pairs and the VSEPR model of molecular geometry. Equipped with computers and computer-generated, three-dimensional electron density maps, scientists are able to view molecules and predict molecular phenomena without even having to get off their chairs ... 

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