Biology 9700 · AS & A Level · Principles of genetic technology
Principles of genetic technology — practice question
Variable number tandem repeats (VNTRs) are repeated, non-coding stretches of DNA. The same VNTR is found at the same locus in different people, but the repeat number within that VNTR is not the same in every individual.
(a)[3]
Explain how gel electrophoresis, in genetic fingerprinting, can distinguish between the VNTRs present at the same loci in different individuals.
(b)[2]
Complete Fig. 3.2 by drawing the stained DNA that would be produced by an individual heterozygous for the sickle cell allele, HbA HbS. Put your answer on to Fig. 3.2.
(c)[3]
Describe the various circumstances in which this genetic screening for the sickle cell allele, HbS, may be used.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “VNTRs containing more repeats are longer / have greater mass” …