Question

15. In VNTR analysis, a conclusion that indicates “Inclusion” means which of the following: a. The profiles are different b. The profiles match c. No conclusion can be made d. The samples are from different sources

16. In RFLP profiling, DNA degradation can be detected using which of the following: a. Agarose gel electrophoresis b. Partial restriction digestion c. PCR analysis d. All of the above

17. This term refers to the deviation of the specificity of the cleavage site of a restriction enzyme: a. Point mutation b. Point degradation c. Partial stripping d. Star activity

18. In RFLP, this is caused by the substitution, deletion, or insertion of a single nucleotide a. Point mutation b. Point degradation c. Partial stripping d. Star activity

19. Which of the following loci was used by forensic DNA labs for amplified fragment length polymorphisms: a. D1S80 b. D1S99 c. T1S80 d. DS1980

20. Which of the following cases would be suitable for AFLP analysis: a. A cold case with a degraded sample b. A paternity case c. A case with mtDNA d. None of the above

Answer 1

15. VNTRs (Variable Number Tandem Repeats) are also called minisatellites. These consist of hypervariable repeat regions of DNA having a basic repeat sequence of 11-60 bp and flanked on both sides by restriction sites. The number of repeats show a very high degree of polymorphism and size of the VNTR varies from 0.1-20 Kb. The length of minisatellites and position of restriction sites is different for each person. Therefore, when the genomes of two people are cut using the same restriction enzyme, the length and number of fragments obtained is different for both. The following conclusions can be made from VNTRs. If the VNTR fragments are at their correspondant position, they are considered to be a match. This means Inclusion which indicates the profiles match. On the other hand, if the profiles are different, then the two DNA samples are from different sources and have different origins (exclusion). So the correct option is (b)

16. In RFLP analysis,the DNA needs to be intact but DNA degradation may occurs resulting in breakage of the strands. The severity of DNA degradation results in smallest fragments with a lesser probability to detect the alleles. But the DNA degradation can be detected before employing RFLP, by the use of agarose gel electrophoresis which is used to detect the yield and integrity of isolated DNA. So the correct option is (a).

17. The restriction enzymes which are also called molecular scissors cuts at a specific recognition sequence of the DNA strand. But sometimes, if the prerequisite conditions for restriction enzymes digestion are not met adequately, then the cleavage is not specific. The restriction ezymes then deviate from the specific cleavage site and cleave sequences that are similar but not exactly identical to the recognition sequence. This changed specificity is called star activity. So the deviation of the specificity of the cleavage site of a restriction enzyme is referred as star activity. The correct option is (d).

18. Point mutation results from change in singlr base pair of DNA. It may result from insertion, deletion, substitution of a single nucleotides. The subsequent insertion, deletion or substitution may result in gain or loss of a restriction site in which DNA cutting by relevant restriction endonuclease enzymes leads to restriction fragments length poly morphism (RFLP). So the correct option is (a)