Answer :
Final answer:
Phage-typing is a method to classify bacterial strains based on their susceptibility to certain bacteriophages, unlike gel electrophoresis, which separates DNA molecules by size and charge for analysis. Phage-typing is useful in epidemiology to track bacterial strain spread, while gel electrophoresis is a broader DNA technique for DNA analysis.
Explanation:
The student asked about phage-typing of bacterial strains, which is distinct from DNA techniques involving gel electrophoresis. Phage-typing is a method used to identify and differentiate between strains of bacteria based on their susceptibility to various bacteriophages, which are viruses that infect bacteria. This method exploits the specificity of bacteriophages to their bacterial hosts and classifies bacteria into types according to which phages they are susceptible to.
It is a classical microbial identification and typing technique employed in epidemiology to track the spread of bacterial strains, often in cases such as foodborne outbreaks or hospital-acquired infections.
Gel electrophoresis, on the other hand, is a laboratory technique used to separate DNA, RNA, or protein molecules based on their size and electrical charge. During gel electrophoresis, DNA fragments are separated in a gel matrix by applying an electric field.
The negatively charged DNA molecules move towards the positive electrode, with smaller fragments moving faster and thus farther than larger fragments. The resulting pattern of DNA bands can be visualized with a DNA-specific stain such as ethidium bromide, allowing for the analysis of DNA fragments of different lengths.
