Multiple Choice
Which one of the following statements accurately describes gel electrophoresis?
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18. Biotechnology
Gel Electrophoresis
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Which property of DNA allows gel electrophoresis to separate DNA fragments during forensic and paternity testing?
A
The presence of thymine bases
B
The double-helix structure of DNA
C
The ability of DNA to replicate
D
The negative charge of the phosphate backbone
Verified step by step guidance1
Understand the principle of gel electrophoresis: Gel electrophoresis is a technique used to separate molecules, such as DNA, based on their size and charge. DNA fragments move through a gel matrix when an electric current is applied.
Recognize the key property of DNA: DNA has a negatively charged phosphate backbone due to the phosphate groups in its structure. This negative charge is uniform across all DNA molecules, regardless of their sequence.
Relate the negative charge to movement in the gel: When an electric current is applied, the negatively charged DNA fragments are attracted to the positive electrode (anode) at the opposite end of the gel.
Understand the role of fragment size: Smaller DNA fragments move more easily through the gel matrix and travel farther, while larger fragments encounter more resistance and move more slowly. This size-based separation is crucial for analysis.
Conclude the relevance to forensic and paternity testing: The separation of DNA fragments by size allows scientists to compare DNA profiles, identify individuals, and determine genetic relationships, making the negative charge of the phosphate backbone essential for this process.
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