Which property of satellite DNA is used to distinguish it from the rest of the genome during centrifugation?
- Color
- Solubility
- Charge
- Buoyant density
Explanation: Satellite DNA has a different base composition (A:T or G:C rich) compared to bulk DNA, giving it a distinct buoyant density.
What is the purpose of 'Blocking' the membrane before adding the probe?
- Stop DNA movement
- Remove extra salts
- Prevent non-specific binding
- Harden the membrane
Explanation: Blocking ensures the probe only sticks to the DNA of interest and not to the empty spaces on the membrane, reducing 'background noise'.
Satellite DNA is generally categorized as either 'micro' or 'mini' based on the:
- Length of segment
- Shape of DNA
- Number of strands
- Type of sugar
Explanation: Categorization into micro-satellites or mini-satellites depends on base composition, length of the segment, and the number of repetitive units.
Which of the following describes 'Satellite DNA' base composition compared to bulk DNA?
- No nitrogenous bases
- Vastly different
- Purely phosphorus
- Always identical
Explanation: Satellite DNA often has an unusual concentration of A:T or G:C base pairs, which is what allows it to separate during centrifugation.
The technique used to separate DNA fragments based on their size is called:
- Centrifugation
- Electrophoresis
- Distillation
- Chromatography
Explanation: Gel electrophoresis uses an electric field to move negatively charged DNA through a gel matrix; smaller fragments move faster and further.
Which of the following is the primary reason why non-coding DNA shows high polymorphism?
- Mutations accumulate freely
- Vital for life
- Resistant to UV
- Protects the brain
Explanation: Because non-coding regions do not produce proteins, mutations occurring there do not affect survival and are passed down through generations.
DNA fingerprinting is most commonly used in the justice system for:
- Determining age
- Predicting future
- Forensic identification
- Measuring height
Explanation: It is a powerful tool for identifying criminals by matching DNA found at a crime scene with that of a suspect.
DNA Fingerprinting relies on identifying differences in specific repetitive DNA sequences called:
- Exon regions
- Polymorphic DNA
- Coding DNA
- Regulatory DNA
Explanation: The basis of DNA fingerprinting is DNA polymorphism, specifically in non-coding repetitive sequences that vary between individuals.
Regarding the probability of a match, 'Random Match Probability' (RMP) should be:
- Extremely low
- Exactly one
- Very high
- Fifty percent
Explanation: The lower the RMP, the higher the confidence that the match is not a coincidence and actually belongs to the individual.
The sensitivity of DNA fingerprinting has been greatly increased by the use of:
- Centrifuges
- Acid baths
- PCR techniques
- Microscopes
Explanation: PCR allows scientists to work with ultra-trace amounts of DNA, amplifying the relevant polymorphic regions before analysis.
DNA is negatively charged and moves toward which electrode during gel electrophoresis?
- Cathode
- Neutral plate
- Anode
- Glass slide
Explanation: DNA has a negative charge due to its phosphate backbone; thus, it migrates toward the positive electrode (anode) in an electric field.
Which part of the DNA is used in DNA fingerprinting because it does not code for any proteins?
- Repetitive DNA
- Promoters
- Exons
- Introns
Explanation: Repetitive DNA sequences, which usually do not code for proteins, show high levels of polymorphism and are the focus of fingerprinting.
The technique of DNA Fingerprinting was initially developed by which scientist?
- Alec Jeffreys
- Francis Crick
- Kary Mullis
- James Watson
Explanation: Sir Alec Jeffreys developed the technique in 1984 at the University of Leicester. He used a satellite DNA as a probe that showed high degree of polymorphism.
The probability of two unrelated individuals having the same DNA fingerprint is:
- Extremely low
- One in million
- One in hundred
- Highly probable
Explanation: Due to the extreme variability in VNTR copy numbers across the genome, the chance of a random match is virtually zero.
Which of the following is NOT required for a successful DNA fingerprinting process?
- Protein translation
- Autoradiography
- Hybridization
- DNA isolation
Explanation: DNA fingerprinting analyzes the DNA directly; protein translation (making proteins from RNA) is not a part of this process.
The 'Southern Blot' technique, widely used in molecular biology for the detection of specific DNA sequences, is named after which pioneering scientist?
- Robert West
- Edwin Southern
- Alan East
- Edward Southern
Explanation: The Southern blot technique was developed by the British biologist Edwin Southern in 1975. The subsequent naming of 'Northern' (for RNA) and 'Western' (for proteins) blots were biological puns based on his surname.
The radioactive labels used in the DNA probes are typically isotopes of:
- Phosphorus
- Carbon
- Nitrogen
- Hydrogen
Explanation: Phosphorus-32 ($^{32}P$) is commonly used to label DNA probes because phosphorus is a natural component of the DNA backbone.
In DNA fingerprinting, the degree of 'Polymorphism' refers to the variation in:
- Sugar type
- Nucleotide sequence
- Phosphate count
- Cell size
Explanation: DNA polymorphism is the existence of multiple variants (alleles) at a genetic locus within a population.
Which technique is often used to amplify a small amount of DNA before performing fingerprinting?
- ELISA
- Western Blot
- PCR
- NMR
Explanation: Polymerase Chain Reaction (PCR) is used to create millions of copies of a DNA sample, allowing forensic analysis even from a single cell.
The use of DNA evidence in Indian courts was pioneered in the late:
Explanation: India began utilizing DNA fingerprinting for legal cases in the late 1980s, largely due to the work of the CDFD and CCMB.
Which of the following describes a 'Homozygous' condition at a VNTR locus?
- Triple repeat numbers
- No repeat numbers
- Same repeat numbers
- Different repeat numbers
Explanation: If an individual inherits the same number of repeats from both parents for a specific locus, they are homozygous at that site.
In the methodology of DNA fingerprinting, what is the role of 'Endonucleases'?
- Synthesize DNA
- Digest DNA
- Amplify DNA
- Ligate DNA
Explanation: Restriction enzymes (Endonucleases) cut the DNA at specific palindromic sequences to create fragments of predictable sizes.
The 'polymorphism' in DNA sequences arises primarily due to:
- Mutations
- Translation
- DNA Repair
- Transcription
Explanation: DNA polymorphism arises due to mutations. While mutations in coding sequences may be harmful, mutations in non-coding sequences accumulate over generations, creating the genetic diversity used in DNA fingerprinting.
What is the full anatomical expansion of the abbreviation 'VNTR' utilized in DNA profiling and genetic fingerprinting?
- Variable Number of Tandem Repeats
- Visual Nucleotide Tandem Repeats
- Variable Nitrogenous Tissue Repeats
- Visualized Nuclear Template Regions
Explanation: VNTR stands for Variable Number of Tandem Repeats. These are distinct sequences in the genome where a short nucleotide pattern is repeated a variable number of times, making them highly unique to individuals.
DNA fingerprinting is widely used in wildlife conservation to identify:
- Animal weight
- Dietary habits
- Poached materials
- Migration routes
Explanation: It can identify whether a skin, ivory, or meat sample belongs to a protected species, aiding in the fight against illegal trade.
Repetitive DNA does not code for proteins but is important for:
- Digestion
- Photosynthesis
- Cellular respiration
- Chromosome structure
Explanation: Many repetitive DNA sequences play structural roles in chromosomes, such as at centromeres and telomeres.
Which organization in India is a pioneer in the field of DNA Fingerprinting and Diagnostics?
Explanation: The Centre for DNA Fingerprinting and Diagnostics (CDFD) in Hyderabad is a premier institute for DNA-based testing and research in India.
In forensic science, a 'partial' DNA profile may be obtained if the sample is:
- Too large
- Highly degraded
- Freshly collected
- Stored in ice
Explanation: Old or environmentally damaged samples may yield only a few bands, making identification more difficult but not impossible.
A mutation is technically defined as a 'polymorphism' if its frequency in a population is greater than:
Explanation: In human genetics, a variation is called a DNA polymorphism if more than one variant (allele) at a locus occurs with a frequency greater than 0.01.
What is the primary function of the 'Alkaline solution' used during the blotting process?
- Join DNA fragments
- Denature the DNA
- Stain the DNA
- Speed up movement
Explanation: Alkaline treatment breaks the hydrogen bonds, making the DNA single-stranded so it can bind to the probe later.
In a crime scene investigation, why are multiple VNTR loci analyzed?
- Save time
- Increase accuracy
- Standardize color
- Reduce cost
Explanation: Analyzing several different loci significantly reduces the chance that two people might coincidentally share the same pattern.
Which of the following describes the heritability of DNA polymorphisms?
- Environmentally induced
- Inherited from parents
- Not heritable
- Only maternal origin
Explanation: Polymorphisms are inherited from parents to children, which is why DNA fingerprinting is highly effective in paternity testing.
The bulk DNA forms a major peak during density gradient centrifugation, while small peaks are called:
- Template DNA
- Passive DNA
- Primary DNA
- Satellite DNA
Explanation: Repetitive DNA sequences separate from bulk genomic DNA as different peaks during centrifugation; these are referred to as satellite DNA.
Regarding the DNA fingerprint pattern, a child's band pattern will be:
- A combination match
- Unique completely
- Identical to siblings
- Matches one parent
Explanation: Since a child inherits half of their DNA from each parent, their fingerprint pattern will be a combination of bands from both parents.
DNA fingerprinting is an invaluable tool for studying which of the following?
- Population genetic diversity
- Soil mineral content
- Digestive enzyme efficiency
- Muscle contraction speed
Explanation: It helps researchers track genetic variation, evolutionary relationships, and population structure in various species.
Which process involves the pairing of a radioactive probe with its complementary DNA sequence on a membrane?
- Denaturation
- Translation
- Polymerization
- Hybridization
Explanation: Hybridization is the binding of a labeled (radioactive or fluorescent) single-stranded DNA probe to its complementary sequence on the membrane.
What percentage of the DNA sequence is identical among all human beings?
- Ninety-five percent
- 99.9 percent identical
- Ninety percent
- Ninety-nine percent
Explanation: About 99.9% of the base sequences among humans are exactly the same; fingerprinting focuses on the 0.1% that differs.
In Southern Blotting, DNA fragments are transferred from the gel to a synthetic membrane made of:
- Polyethylene
- Cellulose acetate
- Nitrocellulose
- Polyvinyl chloride
Explanation: Separated DNA fragments are 'blotted' or transferred onto a nitrocellulose or nylon membrane for further analysis with probes.
Which of the following can 'NOT' be determined using a standard DNA fingerprint?
- Biological father
- Sibling relationship
- Criminal identity
- Current age
Explanation: DNA sequence remains relatively constant throughout life; thus, age cannot be determined by analyzing the genetic fingerprint alone.
The separation of 'Satellite DNA' from bulk DNA is achieved through which process?
- Boiling and cooling
- Chemical bleaching
- Density gradient centrifugation
- Simple filtration
Explanation: Centrifugation in Cesium Chloride (CsCl) separates DNA based on its buoyant density, which depends on its G:C content.
Which branch of biology deals with the legal aspects and applications of DNA fingerprinting?
- Marine Biology
- Evolutionary Biology
- Forensic Biology
- Astrobiology
Explanation: Forensic biology applies biological principles and techniques to solve crimes and legal disputes.
VNTRs, used as probes in DNA fingerprinting, belong to which class of satellite DNA?
- Minisatellite
- Macrosatellite
- Nanosatellite
- Microsatellite
Explanation: Variable Number of Tandem Repeats (VNTRs) are a class of minisatellites where a small DNA sequence is arranged tandemly in many copy numbers.
Which enzyme is used to cut DNA at specific sites during the fingerprinting process?
- RNA Polymerase
- Reverse Transcriptase
- Restriction Endonuclease
- DNA Ligase
Explanation: Restriction endonucleases, often called molecular scissors, are used to digest the DNA into fragments of varying lengths.
The 'Probe' used in DNA fingerprinting is a single-stranded DNA sequence that is:
- Lacking phosphorus
- Coding for insulin
- Double stranded
- Highly repetitive
Explanation: The probe is a labeled, single-stranded repetitive DNA sequence (VNTR) that binds to its complementary sequence on the membrane.
In a paternity dispute, a child's DNA fingerprint must show bands that match:
- Father only
- Mother only
- Both parents
- Neither parent
Explanation: Since every band in a child's DNA profile must be inherited from one of the biological parents, the child's pattern is a combination of both.
Regarding DNA samples, 'Contamination' with foreign DNA can be detected because the pattern will:
- Show extra bands
- Become blurry
- Turn blue
- Disappear completely
Explanation: If a sample is contaminated with DNA from another individual, the resulting fingerprint will contain a mixture of bands from both sources.
The final step of DNA fingerprinting, where the pattern is visualized on a film, is:
- Microscopy
- Autoradiography
- Radiography
- Spectroscopy
Explanation: Autoradiography is used to detect the radioactive probes, producing a pattern of dark bands on an X-ray film.
The specific pattern of bands in a DNA fingerprint is often called a:
- Cellular blueprint
- Genetic barcode
- Sugar chart
- Protein map
Explanation: Much like a retail barcode, the unique arrangement of bands allows for the identification of an individual with high precision.
SNP (Single Nucleotide Polymorphism) refers to a variation at how many base pairs?
Explanation: SNPs are the most common type of genetic variation, occurring when a single nucleotide (A, T, C, or G) in the genome differs.
Which specific class of satellite DNA is also known as 'Short Tandem Repeats' (STRs)?
- Minisatellite
- Microsatellite
- Macrosatellite
- Megasatellite
Explanation: Microsatellites or STRs are smaller than minisatellites, usually consisting of repeating units of 2-6 base pairs.
DNA polymorphism is considered the fundamental basis of both DNA fingerprinting and:
- Genetic mapping
- Cell division
- Protein synthesis
- Energy metabolism
Explanation: Variation at the genetic level (polymorphism) is the common principle used for mapping genomes and identifying individuals.
In forensic DNA profiling, if the extracted DNA profile from a crime scene biological sample matches a suspect's profile exactly, what does it scientifically establish?
- The suspect is unequivocally guilty of the crime.
- The suspect and the victim share a recent common ancestor.
- The DNA sample has been contaminated during forensic analysis.
- The biological material at the scene originated from the suspect.
Explanation: An exact match in the fingerprint pattern between forensic evidence and a suspect's sample provides strong scientific evidence linking their biological material to the scene, though it does not autonomously prove guilt or the exact time of presence.
Which chemical is often used to visualize DNA bands in the gel under UV light?
- Ethidium bromide
- Methylene blue
- Iodine solution
- Crystal violet
Explanation: Ethidium bromide intercalates between DNA bases and fluoresces bright orange when exposed to ultraviolet light.
The copy number of VNTRs varies from person to person, and the size of a VNTR varies from:
- 1 to 100 bp
- 1 to 5 Mb
- 0.1 to 20 kb
- 10 to 50 kb
Explanation: The size of VNTR varies from 0.1 to 20 kilobases (kb). This variation in size creates the unique banding pattern.
Which type of gel is most commonly used to separate DNA fragments in fingerprinting?
- Pectin layer
- Silica gel
- Agarose gel
- Gelatin slab
Explanation: Agarose is a polysaccharide used to create a porous matrix that separates DNA molecules based on their size and length.
The 'Buffer' solution used in electrophoresis is essential to maintain:
- Color intensity
- Gravitational pull
- High temperature
- Constant pH
Explanation: Buffers conduct electricity and maintain a stable pH, which is crucial for the stability of DNA molecules during the run.
The 'Nylon' membrane is preferred over nitrocellulose in modern labs because it is:
- Easily soluble
- More durable
- Cheaper to make
- Highly radioactive
Explanation: Nylon membranes are physically stronger and can be 'stripped' and 're-probed' multiple times compared to brittle nitrocellulose.
Which of the following can be used as a source of DNA for fingerprinting?
- Hair follicles
- Saliva
- Blood
- All of these
Explanation: Any nucleated cell (from blood, hair roots, skin, bone, or saliva) can serve as a source for genomic DNA.
Which of the following pairs of individuals will normally exhibit an exactly identical DNA fingerprint profile?
- Dizygotic (fraternal) twins
- Parent and their direct biological offspring
- Monozygotic (identical) twins
- Siblings born from the same parents but in different years
Explanation: Since monozygotic (identical) twins originate from the division of a single fertilized zygote, their genomic DNA sequences—and thus their DNA fingerprints—are identical.
DNA fingerprinting is also used in 'Anthropology' to trace:
- Bone density
- Daily habits
- Human migration
- Individual wealth
Explanation: By comparing genetic markers across populations, scientists can map the movement and origins of human ancestors.