Biology 9700 · AS & A Level · Principles of genetic technology
Principles of genetic technology — practice question
Variable number tandem repeats (VNTRs) are repeating, non-coding stretches of DNA. The same VNTR is found at the same locus in different individuals, but the repeat count in that VNTR differs from person to person.
(a)[3]
Explain how, in genetic fingerprinting, gel electrophoresis can tell apart the VNTRs found at the same loci in different individuals.
(b)[2]
Gel electrophoresis is also used in genetic screening. Complete Fig. 3.2 by drawing the stained DNA pattern that would be expected from an individual who is heterozygous for the sickle cell allele, HbA HbS. Place your answer on Fig. 3.2.
(c)[3]
Describe the different 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 with more repeats are longer or have greater mass” …