The Southern blot technique was developed by Sir Edwin Southern in 1975. This requires separating DNA using agarose gel electrophoresis and then transferring the DNA to a positively charged membrane. The DNA is also probed with a radioactive or fluorescent probe for visualization. Once observed, the DNA can be cut out and isolated.

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- Nucleic Acid Probing
- Agarose Gel Electrophoresis
- Restriction Fragment Length Polymorphism Analysis
- Southern Blots
- Microarray Analysis

Methods for Visualizing DNA

Agarose gel electrophoresis is a way of separating DNA or RNA that are different sizes. Because DNA is negatively charged, it "runs" to the positive electrode through the agarose matrix. The agarose matrix causes larger pieces of DNA to run slower while smaller DNA runs faster which separates the DNA based on size. A DNA Ladder that contains known standard sizes of DNA is run on the gel to use to compare your sample.

Agarose Gel Electrophoresis

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Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Nucleic acid probing can allow a researcher to identify a specific DNA sequence by making a DNA probe. This probe is single-stranded DNA that is complementary to a DNA fragment and has a tag that can be visualized. DNA must be denatured to allow the probe to bind to the DNA.

Nucleic Acid Probing

Restriction fragment length polymorphism uses restriction enzyme sites found in DNA to give a signature pattern of DNA after restriction enzyme digestion. These can be run on an agarose DNA gel to visualize the fragments.

Restriction Fragment Length Polymorphism Analysis

Southern Blots

Microarray analysis observes the gene expression levels of different cell types, for example a healthy cell vs. a cancerous cell. cDNA can been isolated from different cell types and then red or green probes can be added to the separate samples. Hybridization of the probe with the DNA can be observed in the microarray. Based on those probes, the levels of expression read by the microarray indicates the levels of gene expression.

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