BMI_Lab9DNA_RDigest

BMI_Lab9DNA_RDigest - Laboratory: IX Topic: Quantitation of...

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Laboratory: IX Topic: Quantitation of DNA by UV spectrophotometry and Plasmid restriction digest Introduction: Quantitation of DNA by UV spectrophotometry : DNA preparations may contain contaminating proteins, RNA and other cellular material as well as ethanol and salts associated with the DNA isolation procedures. Good quality DNA preparations are required for downstream applications in biotechnology and for gene analysis. The purity and concentration of a DNA sample can be analyzed using spectrophotometry. DNA purity is estimated using the ratio of absorbances (also known as optical density (OD) at 260 and 280 nm. The A 260 /A 280 value should fall in the range of 1.8 – 2 for good quality DNA. The concentration of a DNA sample is determined by measuring the absorbance at 260nm. A pure DNA solution in distilled water with an absorbance of 1 at 260nm contains has a concentration of 50 μ g/ml of DNA. This formula is used to calculate the concentration of unknown DNA samples with known absorbance at 260nm. Restriction Enzymes : A special group of bacterial enzymes known as restriction endonucleases (restriction enzymes, RE) can cut DNA into smaller defined DNA fragments. Restriction enzymes protect bacteria from phage and viral DNA infections. Restriction enzymes digest the invading DNA (example: lambda ) phage DNA) into smaller ineffective fragments. Restriction enzymes recognize a specific DNA sequence or
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BMI_Lab9DNA_RDigest - Laboratory: IX Topic: Quantitation of...

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