The Molecular Biology Notebook Online
Control experiment
In scientific experiments, one is always trying to find out what effect varying something has on ones system, e.g. varying the temperautre of an enzyme solution to see what effect this has on the rate of the reaction. To study this one variable - temperature - all other variables must be kept the same. If you have more than one thing changing, you don't know which one is producing the result you are getting. So you have to control all the other variables. In order to understand what is a control, and be able to make the right choice when designing an experiment, I think the best thing would be to go through some experiments and see which controls are used, and what they tell us.
PCR
A PCR reaction is one that always needs a control. As you have seen in the chapter about PCR this reaction will amplify DNA dramatically. If a tiny amount of DNA is found on the pipettes, or in one of the solutions, this may give unwanted amplification products. In order to check that there is no contaminant, one always prepares a sample without any DNA in it, replacing the volume of DNA with sterile distilled water. When counting the samples, just add one for the water. When you see your result on the gel, the track which contained only water should remain empty. If there is something there, then it means that one of the solutions is contaminated, or that your primers make dimers with themselves.
One also need positive controls in PCR to check that the reaction is working. Ideally, the positive control is present in each individual reaction. A blank lane will not mean "no target", but "failed reaction".In immunocytology
One way to visualise structures in a cell slice, is to apply antibodies which are specially designed to highlight these structures. You need a control without the antibody to understand what the slice looks like when there is no antibody.
Related Links
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- Biological Control: A Guide to Natural Enemies in North America: This guide provides photographs and descriptions of biological control (or biocontrol) agents of insect, disease and weed pests in North America. It is also a tutorial on the concept and practice of biological control and integrated pest management (IPM).
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- ChromDB: The Plant Chromatin Database: The mission of ChromDB is to bring together information on homologs of chromatin-associated proteins encoded by plant genomes, organize this information logically and in a comparative manner across species (with reference to other eukaryotes to the extent possible), and make it readily accessible to any members of the research and teaching communities who might be interested in the role played by chromatin proteins in the control of gene expression and genome organization. Our first priority is to provide (a) complete sets of genes encoding chromatin-associated proteins (CAPs) for those plant species with complete or near-complete genome sequences (currently Arabidopsis and rice, with poplar to be displayed in the future), (b) the best available splicing models and predicted protein sequences for these genes, and (c) a molecular phylogenetic context for understanding the evolutionary diversification of these protein families during plant evolution with reference to animal and fungal homologs. Our next priorities will be to identify and present CAP genes in all available EST and partial genomic sequences of other plant species, as well as to provide information regarding their biochemical, developmental, physiological, and cellular functions through a community annotation mechanism.
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Thanks to a student in Monument Charter School for discovering that site and his teacher for letting me know... - Metabolic Simulation software: The software packages available at this site can be used to simulate cellular processes such as metabolic pathways, gene regulatory circuits and signal transduction pathways. SCAMP allows the user to carry out Simulations, Steady state analysis, simple Bifurcation analysis and Metabolic Control Analysis. SCAMP is based on a scripting language which is used to describe cellular systems.
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- REST-284: Relative Expression Software Tool: Therefore new software tools were established, named REST © (Relative Expression Software Tool), which compare two or more treatments groups or conditions (in REST-MCS), with up to 100 data points in sample or control group (in REST-XL), for multiple reference genes and up to 15 target genes (in REST-384) . The mathematical model used is based on the correction for exact PCR efficiencies and the mean crossing point deviation between sample group(s) and control group(s). Subsequently the expression ratio results of the investigated transcripts are tested for significance by a Pair Wise Fixed Reallocation Randomisation Test © and plotted using standard error (SE) estimation via a complex Taylor algorithm.
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