DNA Fingerprinting Questions in English

(A) $DNA$ fingerprinting involves identifying differences in specific regions of $DNA$ sequence called repetitive $DNA$.
These sequences show high degree of polymorphism and are used as the basis for $DNA$ fingerprinting.
Therefore,repetitive $DNA$ is the correct option.

(D) Satellite $DNA$ is classified based on the base composition ($A:T$ rich vs $G:C$ rich),the length of the segment,and the number of repetitive units. The nucleotide sequence itself is not a primary criterion for the classification of satellite $DNA$ into its various categories (like microsatellites or minisatellites); rather,these categories are defined by the length and repetition patterns of the sequences.

(A) $VNTR$ stands for Variable Number Tandem Repeats.
These are short nucleotide sequences that are repeated in tandem in the genome.
$VNTR$s are classified as minisatellites because their repeat units are typically $10-60$ base pairs long.
They are highly polymorphic and are widely used in $DNA$ fingerprinting.

(C) $VNTR$ stands for Variable Number of Tandem Repeats.
These are short nucleotide sequences that are repeated in tandem in the genome.
The number of repeats varies from person to person,which makes them highly useful in $DNA$ fingerprinting and forensic analysis.

(D) In the human genome,a large portion of $DNA$ consists of repetitive sequences that do not code for any proteins or polypeptides.
These are known as repetitive $DNA$ or satellite $DNA$.
$VNTR$ ($Variable$ $Number$ $of$ $Tandem$ $Repeats$) are a type of minisatellite $DNA$.
Both minisatellites and microsatellites are non-coding repetitive sequences used in $DNA$ fingerprinting.
Therefore,all the given options represent non-coding sequences.

(C) $DNA$ fingerprinting relies on the identification of differences in specific regions of $DNA$ sequences.
These regions are known as repetitive $DNA$,which are non-coding sequences that repeat many times.
These sequences show a high degree of variation between individuals,a phenomenon known as $DNA$ polymorphism.
Because these variations are unique to each individual (except in identical twins),they serve as the fundamental basis for $DNA$ fingerprinting.

(C) $DNA$ fingerprinting requires nucleated cells to extract genomic $DNA$.
$RBC$s (Red Blood Cells) in humans are enucleated (they lack a nucleus and $DNA$) at maturity.
Therefore,$RBC$s cannot be used for $DNA$ fingerprinting.
Other options like skin cells,bone cells,and saliva contain nucleated cells from which $DNA$ can be isolated.

(B) $DNA$ fingerprinting is a technique used to identify individuals based on their unique $DNA$ sequences. It was developed by Sir Alec Jeffreys in $1984$ at the University of Leicester. The technique relies on the analysis of variable number tandem repeats $(VNTRs)$,which are specific regions of $DNA$ that vary significantly between individuals.

(B) $DNA$ fingerprinting involves identifying differences in specific regions of $DNA$ sequence called repetitive $DNA$.
These sequences show high degree of polymorphism and are referred to as $Variable$ $Number$ $Tandem$ $Repeats$ $(VNTRs)$.
In the process of $DNA$ fingerprinting,these $VNTRs$ are separated by gel electrophoresis and transferred to synthetic membranes (Southern blotting).
Hybridization is then performed using a radiolabeled $VNTR$ probe to detect these specific sequences,which creates a unique pattern of bands.

(D) $VNTR$ stands for Variable Number Tandem Repeats. These are short nucleotide sequences that are repeated in tandem. The size of $VNTR$ varies in size from $0.1$ to $20 \, kb$ (kilobases). These sequences are highly polymorphic and form the basis of $DNA$ fingerprinting.

(A) The sensitivity of $DNA$ fingerprinting is significantly increased by the use of the Polymerase Chain Reaction $(PCR)$.
$PCR$ allows for the amplification of even minute amounts of $DNA$ found at a crime scene or in a biological sample into millions of copies.
This amplification makes it possible to perform $DNA$ fingerprinting analysis even when the initial $DNA$ sample is very small or degraded.

(D) The correct sequence of steps in $DNA$ fingerprinting is as follows:
$1$. Isolation of $DNA$ $(i)$
$2$. Digestion of $DNA$ by restriction endonucleases $(vi)$
$3$. Separation of $DNA$ fragments by electrophoresis $(iv)$
$4$. Transfer of $DNA$ fragments to a nylon membrane (Southern blotting) $(iii)$
$5$. Hybridization using labeled $VNTR$ probe $(ii)$
$6$. Detection of hybridized $DNA$ fragments by autoradiography $(v)$
Therefore,the correct sequence is $i \rightarrow vi \rightarrow iv \rightarrow iii \rightarrow ii \rightarrow v$.

(A) In the provided figure,the $DNA$ fingerprint patterns for individuals $X$ and $Y$ are identical.
$DNA$ fingerprinting is a technique used to identify individuals based on their unique genetic makeup.
Monozygotic (identical) twins are derived from a single fertilized egg (zygote) that splits into two,resulting in individuals with identical genetic material.
Therefore,they exhibit identical $DNA$ fingerprint patterns.
Dizygotic twins,parents,and children have different genetic compositions and will show distinct $DNA$ fingerprint patterns.

(C) $DNA$ fingerprinting involves the analysis of $DNA$ fragments to identify individuals.
The process includes the following steps:
$1$. Isolation of $DNA$.
$2$. Digestion of $DNA$ by restriction endonucleases.
$3$. Separation of $DNA$ fragments by gel electrophoresis.
$4$. Transferring (blotting) of separated $DNA$ fragments to synthetic membranes,such as nitrocellulose or nylon. This specific technique of transferring $DNA$ to a membrane is known as Southern blotting.
$5$. Hybridization using labeled $VNTR$ probe.
$6$. Detection of hybridized $DNA$ fragments by autoradiography.
Therefore,Southern blot hybridization is the correct technique used in $DNA$ fingerprinting.

(B) The provided figure shows the banding pattern obtained after performing gel electrophoresis on $DNA$ samples from different individuals ($A$,$B$,and $C$).
This technique is used to compare $DNA$ profiles,which is the fundamental principle of $DNA$ fingerprinting.
$DNA$ fingerprinting involves identifying differences in specific $DNA$ sequences,which appear as distinct bands on an electrophoresis gel.
Therefore,the figure represents $DNA$ fingerprinting.

(C) The technique used to identify the binding of a radioactive probe with its complementary $DNA$ is known as Autoradiography.
In this process,a radioactive probe (a single-stranded $DNA$ or $RNA$ tagged with a radioactive isotope) is allowed to hybridize with its complementary sequence on a membrane.
After hybridization,the membrane is exposed to an $X$-ray film.
The radioactive probe emits radiation that exposes the film,creating a dark spot or band where the probe has bound to the target $DNA$.
This allows researchers to detect the presence and location of specific $DNA$ sequences.

(B) Polymorphism in $DNA$ sequence is the fundamental basis for both genetic mapping of the human genome and $DNA$ fingerprinting.
Genetic polymorphism refers to the occurrence of genetic variations at a specific locus in a population,which allows researchers to identify individuals and map genes.

(A) $DNA$ fingerprinting is a widely used modern-day technique in the field of forensic science.
It is used to establish a correlation between biological evidence obtained from a crime scene and a potential suspect.
This technique was first developed and described by Sir Alec Jeffreys in $1984$.

(D) Allelic sequence variation has traditionally been described as a $DNA$ polymorphism if more than one variant (allele) at a locus occurs in a human population with a frequency greater than $0.01$.
In simple terms,if an inheritable mutation is observed in a population at high frequency,it is referred to as $DNA$ polymorphism.
$SNP$ (Single Nucleotide Polymorphism) is a specific type of $DNA$ polymorphism,but the general definition provided in the question refers to $DNA$ polymorphism.

(D) Satellite $DNA$ is a portion of $DNA$ consisting of short,repeating sequences of nucleotide pairs,typically found near the centromere region.
It normally does not code for any protein.
It shows high levels of polymorphism,which is the basis for $DNA$ fingerprinting.
It is classified into various categories such as microsatellites and minisatellites based on the base composition,the length of the segment,and the number of repetitive units.

(A) Polymerase chain reaction $(PCR)$ is a technique used for the amplification (making multiple copies) of specific $DNA$ segments.
It allows for the enzymatic replication of $DNA$ in vitro without the need for living organisms like $E. coli$ or yeast.
In the context of $DNA$ fingerprinting,$PCR$ is essential to amplify small amounts of $DNA$ found at a crime scene or in biological samples to a quantity sufficient for analysis.
It is also widely used in medical diagnostics,genetic research,and paternity testing.

(D) Polymorphism in $DNA$ sequence refers to the variation at the genetic level.
It arises due to mutations,which are heritable changes in the $DNA$ sequence.
These variations serve as the foundation for genetic mapping of the human genome.
Additionally,polymorphism is the fundamental basis for $DNA$ fingerprinting techniques,which allow for the identification of individuals based on their unique genetic profiles.

(A) $VNTRs$ stands for Variable Number of Tandem Repeats.
In the human genome,there are specific regions where short nucleotide sequences are arranged in tandem repeats.
The number of these repeats varies from person to person,which makes them highly polymorphic.
These repeats are inherited from parents and are used as genetic markers in $DNA$ fingerprinting for personal identification.

(B) $DNA$ fingerprinting is a technique used to identify individuals by analyzing specific regions of their $DNA$.
It relies on the presence of satellite $DNA$,which consists of highly repetitive,non-coding sequences of $DNA$ known as Variable Number Tandem Repeats $(VNTRs)$.
These $VNTRs$ show a high degree of polymorphism,meaning they vary significantly between individuals,making them unique to each person (except identical twins).
By comparing these specific repetitive segments,scientists can establish biological relationships,identify pathogens,or solve criminal cases.

(D) $DNA$ fingerprinting involves identifying differences in repetitive $DNA$,not similarities. Since the $DNA$ from every tissue of an individual shows the same degree of polymorphism,it becomes a very useful identification tool in forensic applications.

(D) Minisatellites are short nucleotide sequences that are repeated in tandem.
These sequences are inherently unstable and show a high degree of polymorphism due to mutations.
Because the number,location,and size of these minisatellite repeats vary significantly between individuals,they form the basis of $DNA$ fingerprinting.
Therefore,each individual possesses a unique $DNA$ profile.

(D) The technique of $DNA$ fingerprinting was initially developed by Alec Jeffreys.
He used satellite $DNA$ as a probe that shows a high degree of polymorphism.
$DNA$ fingerprinting using Variable Number Tandem Repeats $(VNTRs)$ is based on the observation that $VNTR$ loci are highly polymorphic,meaning they show significant variation in the number of repeats among different individuals.

(D) $DNA$ fingerprinting is a technique used to identify individuals based on their unique $DNA$ sequences.
Its applications include:
$1$. Forensic science: Used in criminal investigations to identify suspects or victims.
$2$. Determining genetic diversity: Used in evolutionary biology and conservation genetics to study the variation within and between populations.
Since both forensic science and determining genetic diversity are valid applications,the correct choice is $D$.

(A) The technique of $DNA$ fingerprinting involves several steps: isolation of $DNA$,digestion of $DNA$ by restriction endonucleases,separation of $DNA$ fragments by gel electrophoresis,transferring (blotting) of separated $DNA$ fragments to synthetic membranes (like nitrocellulose or nylon),hybridization using labeled $VNTR$ probe,and detection of hybridized $DNA$ fragments by autoradiography.
Therefore,after the digestion of $DNA$ by restriction enzymes,the next step is the separation of these fragments based on their size using gel electrophoresis.

(B) Statement $A$ is correct: Genetic variation within a population is primarily caused by mutations,which are changes in the nucleotide sequence of the genome.
Statement $B$ is correct: The technique of $DNA$ fingerprinting (or $DNA$ profiling) was indeed developed by Sir Alec Jeffreys in $1984$ at the University of Leicester.
Since both statements are factually accurate,the correct option is $(B)$.

(C) In $DNA$ fingerprinting,the $DNA$ fragments are separated by gel electrophoresis and transferred to a synthetic membrane (nylon or nitrocellulose) through a process called Southern blotting.
Hybridisation is then performed using a radioactive $DNA$ probe that binds to complementary sequences.
The detection of these hybridised $DNA$ fragments on the membrane is achieved by exposing the membrane to $X$-ray film,a technique known as autoradiography.

(B) $RFLP$ stands for Restriction Fragment Length Polymorphism.
It is a technique that exploits variations in homologous $DNA$ sequences.
When the genomes of two individuals are digested with the same restriction endonuclease,the resulting $DNA$ fragments vary in length due to differences in the distribution of restriction sites,which is known as polymorphism.

(D) Exons are the coding sequences of a gene that are transcribed into $mRNA$ and translated into proteins.
Micro-satellites and Mini-satellites are types of repetitive $DNA$ sequences found in the non-coding regions of the genome.
These sequences do not code for any proteins and are often used in $DNA$ fingerprinting.
Therefore,both Micro-satellites and Mini-satellites do not code for proteins,making option $D$ the correct choice.

(C) In $DNA$ profiling,the process of transferring separated $DNA$ fragments from an agarose gel onto a synthetic membrane,such as nitrocellulose or nylon,is known as Southern Blotting. This step is essential to immobilize the $DNA$ fragments so they can be hybridized with radioactive probes.

(B) Repetitive sequences are stretches of $DNA$ where a few nucleotide sequences are repeated many times.
Statement $(a)$ is correct: These sequences generally do not code for any proteins and have no known transcriptional function.
Statement $(b)$ is incorrect: Repetitive sequences are primarily found in heterochromatin regions, not euchromatin. Heterochromatin is highly condensed and transcriptionally inactive.
Statement $(c)$ is correct: These sequences form the basis of $DNA$ fingerprinting, which helps in identifying individuals based on their unique $DNA$ profiles.
Since $(b)$ is the only incorrect statement, option $(b)$ is the correct answer.

(B) Microsatellites are a type of variable number tandem repeat $(VNTR)$ that consist of very short $DNA$ sequences,typically $1-6\; bp$ in length,which are repeated multiple times in the genome. These are highly polymorphic and are widely used in $DNA$ fingerprinting.

(C) Assertion $(A)$ is correct because in $DNA$ fingerprinting,$DNA$ fragments are hybridized with radioactive $DNA$ probes (molecular probes) to detect specific sequences.
Reason $(R)$ is incorrect because molecular probes are designed to recognize complementary sequences in $DNA$,not $RNA$,in the context of $DNA$ fingerprinting. Furthermore,the probe is a single-stranded $DNA$ segment.

(A) In $DNA$ fingerprinting,the $DNA$ is digested with restriction enzymes and separated by gel electrophoresis. After blotting,the $DNA$ fragments are hybridized with $VNTR$ (Variable Number Tandem Repeat) probes. The resulting autoradiogram shows a pattern of bands of varying sizes,which is unique to an individual. This specific pattern of bands is referred to as the $DNA$ fingerprint of the organism. Therefore,both the Assertion and the Reason are correct,and the Reason provides the correct explanation for the Assertion.

(A) $DNA$ fingerprinting is a technique used to identify and compare the genetic material of individuals.
It involves analyzing specific regions of $DNA$ known as variable number tandem repeats $(VNTRs)$.
Since the pattern of these repeats is unique to every individual (except identical twins),comparing the $DNA$ profile from a crime scene evidence with that of a suspect allows forensic scientists to determine if they match,thereby identifying the perpetrator.

(D) Southern blotting is a technique used for the detection of a specific $DNA$ sequence in $DNA$ samples.
In this process,$DNA$ fragments are first separated by gel electrophoresis based on their size.
After separation,the $DNA$ fragments are transferred from the gel onto a nitrocellulose or nylon membrane (filter) while maintaining the same distribution pattern as they had in the gel.
This replica on the filter allows for further analysis,such as hybridization with a labeled probe.

(A) The technique of $DNA$ fingerprinting relies on the analysis of $DNA$ fragments. The method commonly used for the detection of specific $DNA$ sequences in a complex sample is known as Southern blotting.
Developed by $E.M. Southern$ in $1975$,this technique involves the transfer of electrophoretically separated $DNA$ fragments to a membrane filter and the subsequent detection of specific sequences by hybridization with a labeled probe.
In forensic studies,Southern blotting is a fundamental tool used to identify individuals by analyzing variable number tandem repeats $(VNTRs)$ or other polymorphic $DNA$ markers.
Northern blotting is used for $RNA$ detection,while Western blotting is used for protein detection. Therefore,Southern blotting is the correct technique for $DNA$ analysis.

(A) $DNA$ fingerprinting involves identifying differences in specific regions of $DNA$ sequence called repetitive $DNA$.
$VNTR$ ($Variable$ $Number$ $Tandem$ $Repeats$) are short nucleotide repeats that vary in number from person to person.
In $DNA$ fingerprinting,these $VNTR$ sequences are used as probes to hybridize with the $DNA$ fragments separated by gel electrophoresis.
Therefore,$VNTR$ is the correct choice as it provides the unique pattern for identification.

(A) Northern blotting is a technique used in molecular biology to study gene expression by detection of $RNA$ (or isolated $mRNA$) in a sample.
In this process,$RNA$ molecules are first separated by size using gel electrophoresis.
After separation,the $RNA$ bands are transferred from the gel onto a solid support membrane,typically made of nitrocellulose or nylon.
Among the given options,$Diazobenzyloxymethyl$ $(DBM)$ paper is a specialized membrane used for the covalent attachment of nucleic acids,specifically used in Northern blotting to immobilize $RNA$ molecules.
Therefore,the correct option is $A$.

(C) Satellite $DNA$ consists of highly repetitive sequences of $DNA$ that do not code for proteins.
These sequences show high levels of polymorphism,meaning they vary significantly between individuals.
This property is the basis of $DNA$ fingerprinting,which is a crucial technique used in forensic science to identify individuals,solve crimes,and determine paternity.

(B) $DNA$ fingerprinting technique was discovered by $A$ Jeffreys in $1984$.
It is a modern molecular technique that compares sets of $DNA$ by identifying specific,identical sequences of nucleotides known as variable number tandem repeats $(VNTRs)$.
This technique is widely used in forensic science for criminal investigations,paternity testing,and identifying genetic relationships.

(B) $DNA$ fingerprinting is a technique that has found immense use in solving cases of disputed parentage and forensic investigations.
It involves the analysis of $VNTR$ (Variable Number Tandem Repeats) or satellite $DNA$ sequences.
Since every individual has a unique pattern of these repeats,$DNA$ samples obtained from blood,hair,or other biological materials can be compared to establish biological relationships or identify individuals.

(B) In $DNA$ fingerprinting,probes are specific sequences of single-stranded $DNA$ that are labeled with radioactive isotopes. These probes are typically derived from minisatellite or microsatellite $DNA$ sequences,which are highly polymorphic regions in the genome. They are designed to hybridize with complementary sequences on the $DNA$ fragments separated during the process.

(C) $DNA$ fingerprinting relies on the identification of differences in specific regions of $DNA$ sequences known as $DNA$ polymorphism. These variations in the nucleotide sequence are unique to every individual (except identical twins) and serve as the fundamental basis for identifying individuals through $DNA$ profiling.

(C) $DNA$ fingerprinting is a modern technique that compares sets of $DNA$ by locating identical sequences of nucleotides.
It is widely used in forensic science to solve many mysteries involving crimes such as murders,robberies,and rapes by matching biological samples found at crime scenes with suspects.

(C) Automated $DNA$ sequencers are based on the chain termination method,which is also known as the dideoxy method. This method was developed by Frederick Sanger in $1977$. It involves the use of dideoxynucleotide triphosphates $(ddNTPs)$ to terminate $DNA$ synthesis at specific bases,allowing for the determination of the nucleotide sequence.