DNA Fingerprinting
Quiz on DNA Fingerprinting Crafted by
Dr. Ankit Srivastava
Assistant Professor
Dr. A.P.J. Abdul Kalam Institute of Forensic Science & Criminology,
Bundelkhand University, Jhansi (U.P.)
Introduction to DNA Fingerprinting
DNA Fingerprinting was first described by Alec Jeffreys, an English geneticist in 1985. He found that DNA possesses certain regions that contains repeated DNA sequences. He also discovered that the number of repeated sequences varies from individual to individual that provide it its uniqueness. DNA fingerprinting is also known by names such as DNA typing and DNA profiling.
Ques 1. The restriction enzymes were discovered by which of the following scientists?
a) Watson and Crick
b) Boyer and Cohen
c) Nathan, Arber and Smith
d) Jacob and Monad
Answer. (c) Nathan, Arber and Smith
Explanation- Restriction enzymes were discovered by molecular biologists Werner Arber, Hamilton O. Smith, and Daniel Nathans in the late 1960s and early 1970s. The ability of the enzymes to cut DNA at precise locations enabled researchers clone genes. The names of restriction enzymes are derived from the genus, species, and strain designations of the bacteria that produce them. For example, the enzyme EcoRI is produced by Escherichia coli strain RY13.
Ques 2. The rate of migration of DNA within agarose gel in the gel electrophoresis technique is primarily based on?
a) The volume of the DNA sample loaded
b) The size of the DNA fragment
c) The number of DNA fragments
d) The negative charge of the DNA
Answer. (b) The size of the DNA fragment
Explanation- The most effective and efficient technique of separating DNA fragments is the agarose gel electrophoresis. Agarose is extracted from seaweed genera Gelidium and Gracilaria. It is composed of repeated L- and D- galactose subunits. Polymers of agarose associate non-covalently during gelation and form a network of bundles whose pore size determine a gel’s molecular sieving properties. The rate of migration of DNA molecule depends on many factors such as: The size of the DNA fragment (the smaller fragments moves faster than the larger fragments), agarose concentration, DNA conformation, voltage applied, presence of ethidium bromide, type of agarose, electrophoresis buffer.
Ques 3. In the Sanger method of DNA sequencing, what causes the termination of chain elongation?
a) The incorporation of a regular DNA nucleotide
b) Denaturation of double strand test fragments
c) The incorporation of dideoxy nucleotide
d) When the DNA polymerase encounters a stop codon
Answer. (c) The incorporation of dideoxy nucleotide
Explanation- During in vitro DNA replication, the process of selective incorporation of dideoxy nucleotide by DNA polymerase is known as Sanger sequencing which is widely used for the SNVs detection and the event of incorporation of dideoxynucleotide is known as chain termination.
Ques 4. The length of a haploid DNA is approximately?
a) 2 billion
b) 4 Million
c) 3 billion
d) None of these
Answer. (c) 3 billion
Explanation- DNA is made up of 23 pair of chromosomes with a total of about 3 billion DNA base pairs, 22 pairs are autosomal chromosomes and 1 pair is sex chromosomes. Body cells are diploid that makes a total of 6 billion base pairs of DNA per cell.
Ques 5. Every individual can be discriminated from another by a probability factor of?
a) 1.683 X 10-15
b) 1.683 X 10-10
c) 6.683 X 10-15
d) 6.683 X 10-10
Answer. (a) 1.683 x 10-15
Explanation- DNA loci along with their STRs are inherited by the offspring from their parents during meiosis and every individual can be discriminated from another by a probability factor of 1.683 x 10-15, that is, one individual can have the same DNA pattern with another only in a population of 594 trillion except the monozygotic twins as they carry the same loci with the same repeat pattern.
Ques 6. Which report defined the DNA evidence as gold standard?
a) Report of European Academy of Forensic Science
b) NAS report 2009
c) ASTM standard
d) FBI manual
Answer. (b) NAS report 2009
Explanation- The National Academy of Sciences (NAS) is a private, non-profit, self-perpetuating society of eminent scholars involved in scientific and engineering research, devoted to the advancement of science and technology and to their use for the general welfare.
Ques 7. In the first case, where DNA fingerprinting was applied for the criminal investigation, DNA profiling not only identified the culprit but also exonerated the innocent. In this case, what was the name of the person that was acquitted?
a) Dawn Ashworth
b) Pitchfork
c) Buckland
d) Ian Kellay
Answer. (c) Richard Buckland
Explanation- Initially in this case Buckland was arrested as he had the knowledge about the victim’s body but when the DNA fingerprinting method was utilized Colin Pitchfork was convicted for double rape and murder as his DNA profile matched with the DNA that was found at the scene of crime.
Ques 8. ABI PRISM 310 and 3100 Avant are?
a) Commercial STR kits
b) RT-PCR systems
c) Capillary electrophoresis systems
d) NGS Kits
Answer. (c) Capillary electrophoresis systems
Explanation- Capillary electrophoresis is widely utilized in varied areas such as analytical chemistry, chiral separations, clinical, forensics, molecular biology, natural products, organic chemistry, and the pharmaceutical industry. Its forensic applications include fragment analysis, DNA sequencing, SNP typing, and analysis of gunshot residues, explosive residues, and drugs. Due to its single-base resolution capability, the fragment analysis is widely used method for STR profiling for human identification.
Ques 9. The extraction buffer contains the Tris-base or Tris-HCL of pH?
a) 5.5-6.0
b) 7.5-8.0
c) 11.0-12.0
d) 3.0-4.0
Answer. (b) 7.5-8.0
Explanation- The extraction buffer contains the biological buffers to maintain a stable pH and they are likely to interact with lipopolysaccharide present in the cell membrane, helping further in the destabilization of the membrane.
Ques 10. Detergents, like SDS, are part of the extraction buffer, contains?
a) Hydrophobic tail and Hydrophilic head
b) Hydrophobic head and Hydrophilic tail
c) Both a and b; according to the type of detergent
d) None of these
Answer. (a) Hydrophobic tail and hydrophilic head
Explanation- Hydrophobic tail and hydrophilic head allows detergents to aggregate in aqueous medium. Biological detergents are utilized to disintegrate the cell membrane in order to release and solubilize membrane bound proteins.
Ques 11. For the precipitation of the DNA which of the following is used?
a) EDTA
b) Proteinase K
c) Absolute Ethenol (65%)
d) DTT
Answer. (c) Absolute Ethenol (65%)
Explanation- Absolute ethanol (65%) as DNA is insoluble in ethanol. The ethanol molecules can form hydrogen bonds with water molecules decreasing the number of water molecules required to hydrate DNA which causes the aggregation of DNA.
Ques 12. Before 1985, DNA fingerprinting was being applied for?
a) Geneology
b) Human genetic disease
c) Personal identifications
d) All of these
Answer. (b) Human genetic disease
Explanation- In 1979, Alec Jeffreys described how to detect human genetic variation at the DNA level and estimated the genomic sites for genetic variation. In 1984, he was first to discover the DNA Fingerprinting technique and in 1985 it was first used to solve the paternity case. Earlier DNA fingerprinting was utilized in legal disputes to solve crimes and to identify inherited genetic diseases and to identify genetic matches between tissue donors and recipients.
Ques 13. DNA profiling have dominantly contributed in the investigation of Human Trafficking and child abuse cases. In this regard, the DNA-PROKIDs is the initiative of which of the following?
a) USA
b) England
c) Spain
d) UNESCO
Answer. (c) Spain
Explanation- It is an international project, on fight against human trafficking using genetic identification of victims, created in 2009 and it’s headquarter is at the University of Granada, Spain.
Ques 14. In which case, for the first time the admissibility of the DNA was challenged seriously in the court of law?
a) Peoples vs. Castro
b) Frye vs US
c) Rohit Shekhar vs ND Tiwari
d) None of these
Answer. (a) People vs Castro
Explanation- In People vs Castro murder case, the New York Supreme Court defined numerous issues related to the admissibility of DNA evidence. In this case DNA typing technique was applied and it was so flawed that evidence of match was inadmissible.
Ques 15. In India, Parentage determination is governed by the…..
a) Sec 120 of IEA
b) Sec. 112 of IEA
c) Sec. 120 of CrPC
d) Sec. 112 of CrPC
Answer. (b) Section 112 of IEA
Explanation- Section 112 of Indian Evidence Act refers to the legitimacy of a child born during wedlock. The law assumes that if a child is born during the continuance of a valid marriage between his mother and any man, or within 280 days after the dissolution of marriage, mother remaining unmarried, shall be conclusive proof that he is the legitimate son of that man, unless it can be shown that the parties to the marriage had no access to each other at any time when he could have been begotten.
Ques 16. DNA evidence was entered in the Indian court room for the first time in the case of?
a) Kunhiraman vs Manoj
b) Banarasi das vs Teeku Datta
c) Naina sahni (tandoor) case
d) Gautam Kundu vs state of Bengal
Answer. (a) Kunhiraman vs Manoj
Explanation- It was the first case of DNA profiling case used to solve paternity dispute. Various DNA profiles were developed in this case and it was seen that Manoj (son) has inherited total 15 DNA bands which were all derived from Kunhiraman (father). So it was opined that Kunhiraman was the biological father of 17 years old Manoj.
Ques 17. In India, the first DNA test for the forensic purpose was conducted at?
a) CFSL Kolkata
b) SFSL Kolkata
c) CCMB
d) CDFD
Answer. (c) CCMB
Explanation- The first DNA case was paternity case of Kerala and the centre for the DNA analysis was CCMB, Hyderabad. They used the blood sample to perform the paternity test. The Centre for Cellular & Molecular Biology (CCMB) is a research organization. Its objectives are to conduct high quality basic research and training in frontier areas of modern biology, and promote centralised national facilities for new and modern techniques in the inter-disciplinary areas of biology.
Ques 18. Pyrosequencing techniques
a) Use cytbLoci
b) Pedigree analysis of a particular individual
c) Direct sequencing of small DNA fragments in a single run
d) Associated with NGS
Answer. (c) Direct sequencing of small DNA fragments in a single run
Explanation- It is a reliable, fast and high-throughput technique as it can do direct sequencing of small DNA fragments in a single run. It is based on sequential addition and inclusion of nucleotides that can be quantified by converting naturally occurring pyrophosphate into light signal in real time. This technique is used in the detection of SNPs, deletions, insertions, gene copy number and DNA methylation.
Ques 19. The human mitochondrial genome consists of a double stranded circular DNA of?
a) 10 kb
b) 16.6 kb
c) 20.4 kb
d) 22.3 kb
Answer. (b) 16.6 kb
Explanation- The human mitochondrial DNA is a double stranded circular molecule of 16,569 base pairs (16.6 kb) in length. It contains 37 genes, 28 genes are encoded by the heavy strand and 9 are encoded by the light strand of the mitochondrial DNA. It encodes for 2 rRNAs and 22tRNAs and 13 proteins.
Ques 20. Which of the following sentence(s) is true about the ‘MiniFiler Kit’?
(a) The first commercial STR kit
(b) It was developed for the genotyping of the degraded DNA samples
(c) It was developed to amplify ‘miniSTRs’
(d) All are true
Answer. (d) All are true
Explanation- Minifiler kit was developed to increase the amount of information derived from the degraded DNA samples. The kit contains reagents for the amplification of 8 STRs.