Distinguishing Alleles with RFLP: Correct Answer and Full Explanation

Restriction Fragment Length Polymorphism (RFLP) detects DNA variations by comparing fragment sizes after restriction enzyme digestion. The correct answer is (A) Differences in the number of recognition sites for a given restriction enzyme.​

RFLP Basics

RFLP analyzes polymorphisms from variable DNA fragment lengths produced by restriction enzymes cutting at specific recognition sequences. Different alleles yield distinct fragment patterns on gel electrophoresis if cut sites vary. This method, foundational in genetics, identifies mutations altering enzyme sites.​

Correct Answer: Option (A)

Differences in recognition sites mean one allele may have more (or fewer) cut points for the enzyme, producing shorter or more fragments versus another allele’s longer ones. These length variations create unique banding patterns detectable via Southern blotting. For example, a point mutation adding or removing a site directly enables allele discrimination in RFLP.​

Incorrect Options Explained

Option (B): Recombination Ability

Recombination shuffles alleles during meiosis but does not alter restriction fragment lengths or produce detectable RFLP patterns. RFLP relies solely on static sequence differences affecting digestion sites, not dynamic crossing-over.​

Option (C): Segregation Ability

Segregation follows Mendel’s laws, separating alleles into gametes independently of restriction enzyme activity. It influences inheritance ratios but plays no role in generating or visualizing RFLP fragment differences.​

Option (D): Tandem Repeats

Tandem repeats cause length polymorphisms detected by techniques like VNTR analysis or STR profiling, not standard RFLP. RFLP distinguishes via site presence/absence, whereas repeats primarily affect PCR-based fragment sizing.​