DNA fingerprinting lane unknown sample, number of fragments length of fragments
The correct answer and explanation is:
Correct Answer:
DNA fingerprinting involves comparing the number and lengths of DNA fragments in a sample. The unknown sample is analyzed by comparing its fragment pattern (number and size) to known samples. These fragments appear as bands in lanes on a gel (usually agarose gel electrophoresis).
To determine the correct identity or match for an unknown DNA sample:
- Count the number of DNA fragments (bands) in the lane of the unknown.
- Measure the length (size) of each fragment, typically in base pairs (bp).
- Compare these with the patterns of known individuals’ DNA.
300-Word Explanation:
DNA fingerprinting (also called DNA profiling) is a technique used to identify individuals based on the unique patterns in their DNA. It relies on the analysis of specific regions of DNA that vary greatly among people, often using short tandem repeats (STRs).
The process begins with extracting DNA from a sample, then cutting it using restriction enzymes that target specific sequences. This produces fragments of different lengths. These fragments are then separated using gel electrophoresis, where an electric current pulls negatively charged DNA fragments through a gel matrix. Smaller fragments move faster and farther than larger ones.
The gel results in lanes with bands that represent DNA fragments. Each band’s position corresponds to its length, and the number of bands depends on the number of restriction sites and repeat regions in the sample.
To identify an unknown DNA sample:
- Compare the number of bands: If the unknown sample has, for example, 5 bands, compare that to known samples that also have 5.
- Compare the length of bands: A match requires the bands in the unknown to be at the same position (same length) as in a known sample.
If both the number and size of fragments match exactly, the unknown sample likely belongs to that individual. This method is highly accurate and widely used in forensic science, paternity testing, and genetic research.
Thus, DNA fingerprinting allows precise identification using the number and length of DNA fragments in an electrophoresis lane.