Biology

DNA and Genetics

985 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which one of the following is not a correct match?

  1. Tumor Inducing - Ti plasmid

  2. DNA probe - Identifies the desired DNA fragment

  3. PCR - DNA staining

  4. Agarose - Sea weeds
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

PCR is a method for DNA amplification, not DNA staining. DNA staining is typically performed using dyes like ethidium bromide or SYBR Green.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

The correct sequence of different steps of polymerase chain reaction is

  1. Annealing denaturation extension

  2. Denaturation extension annealing

  3. Denaturation annealing extension

  4. Extension denaturation annealing
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Polymerase chain reaction is a technique used to replicate a fragment of DNA so as to produce many copies of a particular DNA sequence. A single PCR amplification cycle involves three basic steps: denaturation, annealing and extension (polymerisation).
So, the correct answer is 'Denaturation annealing extension'.
Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Given figures represent the steps involved in polymerase chain reaction (PCR). Identify the steps A, B, C and D, and select the correct option.

A B C D
a Denaturation at 94-96 degree C Extension through Taq polymerase at 72 degree C Repetition of denaturation and annealing Annealing at 72 degree C
b Denaturation at 94-96 degree C Annealing at 40-60 degree C Extension through Taq polymerase at 72 degree C Repetition of denaturation and annealing
c Denaturation at 40-60 degree C Annealing at 72 degree C Extension through Taq polymerase at 94-96  degree C Repetition of denaturation and annealing
d Extension through Taq polymerase at 72 degree C Denaturation at 40 degree C Annealing at 72 degree C Repetition of denaturation and annealing

  1. a

  2. b

  3. c

  4. d
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Polymerase chain reaction involves the steps:

  • Denaturation
  • Annealing 
  • Extension
  • Amplification
So, the correct option is 'Option B ' .

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Study the following statements regarding recombinant DNA technology and select the incorrect ones

(i) Taq polymerase extends the primers using the nucleotides provided in the reaction
(ii) Antibiotic resistance genes are considered as desirable genes in recombinant DNA technology
(iii) DNA fragments are separated according to their charge only, in agarose gel electrophoresis
(iv) Transformation is a procedure through which a piece of DNA is integrated into the genome of a host bacterium
(v) To produce higher yields of the desired protein, host cells can be multiplied in a continuous culture
(vi) Downstream processing is one of the steps of polymerase chain reaction

  1. (i), (iii) and (vi)

  2. (i), (iii) and (v)

  3. (ii), (iii) and (v)

  4. (i), (iv) and (v)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Antibiotic resistance genes are selectable markers. Desirable genes are the ones which are introduced in the vector for getting desired protein product. In agarose gel electrophoresis, DNA fragments are separated according to their charge and size. After the formation of the product in a bioreactors, it undergoes through some processes before a finished product is ready for marketing. The processes include separation and purification of products which are collectively called as downstream processing.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Reaction of 1989 was

  1. Nicking by restriction endonucleases

  2. Polymerase chain reaction

  3. Reverse genetics

  4. Splicing
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In 1985 Norm Arnheim, also a member of the development team concluded his sabbatical at Cetus and assumed an academic position at USC. He began to investigate the use of PCR to amplify samples containing just a single copy of the target sequence. By 1989 his lab developed multiplex-PCR on single sperm to directly analyze the products of meiotic recombination.

So, the correct answer is 'Polymerase chain reaction.'

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

DNA taq polymerase enzyme is isolated from which bacteria?

  1. Agrobacterium

  2. Thermus aquaticus

  3. Bacillus thuringiensis

  4. E.coli
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA polymerase enzyme was isolated from a thermophilc bacteria called Thermus aquaticus. This is an enzyme used frequently to make multiple copies of segment of DNA by a technique called polymerase chain reaction.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Thermal cycle is used in

  1. Radioactivation

  2. Chemical reaction

  3. Polymerase chain reaction

  4. Enzyme catalysed reactions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A thermal cycler is an instrument used to perform PCR by precisely controlling the temperature changes required for denaturation, annealing, and extension.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

One of the methods of which DNA cannot be transferred to the host cell is by

  1. Microinjection

  2. Gene gun

  3. Disarmed pathogen vectors

  4. Polymerase chain reaction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

PCR is a technique for amplifying DNA in vitro. It is not a method for transferring DNA into a host cell; methods like microinjection, gene guns, and vectors are used for transformation.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Polymerase chain reaction

  1. Is a method of synthesising human protein from human DNA

  2. Uses restriction enzymes

  3. Can produce billions of copies of a DNA fragment

  4. Takes place naturally in bacteria
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

PCR is specifically designed to amplify a specific DNA sequence, producing billions of copies from a small starting amount of template DNA.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

How many copies of the DNA sample are produced in PCR technique after 6-cycle?

  1. $4$
  2. $32$
  3. $64$
  4. $16$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Polymerase chain reaction (PCR) is a technique that exponentially amplifies a single copy of a specific DNA segment. It generates thousands of copies of that specific DNA segment. After completion of one cycle, 2 copies are produced from a single DNA segment. After completion of the second cycle, 2$^2$ = 4 copies are produced. Similarly, after n$^{th}$ cycle, 2$^2$ copies are produced, where n is the number of cycles. Hence, after completion of 6 cycle, 2$^6$ = 64 copies will be produced. 

Thus, the correct answer is '64.'

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which of the following is not necessary to execute polymerase chain reaction successfully?

  1. All four DNA bases

  2. Short DNA base pairs

  3. DNA polymerase

  4. DNA library
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Polymerase Chain Reaction (PCR) is widely used the method in genetic engineering to prepare the multiple copies of desired DNA. It includes steps of denaturation, annealing extension and last amplification. As DNA is the polymer of four DNA bases present in the base pair and polymerase chain reaction is done in the presence of DNA polymerase enzyme of the DNA that re-studies by the researchers which is said to be DNA library so it is not required in the reaction.

So the correct option is 'DNA library'.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

In reference to DNA polymerase III, which statement is wrong?

  1. It requires ATP For polymerase action.

  2. Required for PCR

  3. More active than DNA Pol I & II

  4. Requires a previously made template to work on
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Like DNA replication in an organism, PCR requires a DNA polymerase enzyme that makes new strands of DNA, using existing strands as templates. The DNA polymerase typically used in PCR is called Taq polymerase, after the heat-tolerant bacterium from which it was isolated (Thermus aquaticus).
So, the correct option is 'Required for PCR'.
Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

In PCR, short primers are added to single stranded DNA molecules in a test tube and the appropriate enzymes are included to make a copy of the DNA. Which of the following primers is needed for copying the single stranded DNA sequence $ 5'TACGGTAGGTC3'$ ?

  1. $5'ATGCC 3'$
  2. $ 5'GACCT 3' $
  3. $ 3'GACCT 5' $
  4. $ 3'ATGCC 5' $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A primer is a short single strand of RNA or DNA (generally about 18-22 bases) that serves as a starting point for DNA synthesis. It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA. The polymerase starts replication at the 3′-end of the primer, and copies the opposite strand. 


For copying the single stranded DNA sequence 5′TACGGTAGGTC3′, complementary sequence possessing primer is needed which is 5′GACCT3′.

So the correct option is '5′GACCT3′'.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

A DNA sequencing reaction was performed with the fragment $5-XXXGCGATCGYYYY-3'$ as the template, dideoxy GTP, all the four $dNTPs$, and the required primers and enzyme. $XXXX$ and $YYYY$ in the given DNA fragment represent primer binding sites. The set of fragments obtained during the reaction will be (the primers are not shown in the amplified fragments).

  1. $5'-CGATCGC-3'$ only
  2. $5'-CG-3', 5'-CGCTAG-3', 5'-CCCTAGC-3'$
  3. $5'-CG-3', 5'-CGATCG-3', 5'-CGATCGC-3'$
  4. $5'-G-3', 5'-GCG-3', 5'-GCGATCG-3'$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A DNA sequencing reaction was performed with the fragment 5−XXXGCGATCGYYYY−3′ as the template, dideoxy GTP, all the four dNTPs, and the required primers and enzyme. XXXX and YYYY in the given DNA fragment represent primer binding sites. The set of fragments obtained during the reaction will be CGATCGC, because if primer is attache to the XXXX binding site it polymerization starts and its complimentary fragment is CGATCGC.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Column I                                            Column II
I. Agarose                                             A. PCR
II. Opines                                              B. Gene gun
III. Biolistic                                           C. Ti plasmid
iv. Thermal cycler                                 D. Sea weeds

  1. $I-D,II-A,III-B,IV-C$
  2. $I-D,II-C,III-B,IV-A$
  3. $I-D,II-A,III-C,IV-B$
  4. $I-A,II-D,III-B,IV-C$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Agarose is derived from seaweeds Gelidium and Gracilaria
  • Opine synthesis is the function of Ti plasmid of Agrobacterium
  • Biolistic is the term used for gene gun used for biotransformation
  • Thermocycler is used to carry out PCR reaction
So the correct option is B. (I−D,II−C,III−B,IV−A)