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

The PCR (polymerase chain reaction) performed on a pool of long oligonucleotides with short overlapping segments is:

  1. intersequence-specific PCR

  2. inverse PCR

  3. hot Start PCR

  4. assembly PCR

  5. helicase-dependent amplification
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The oligonucleotides alternate between sense and antisense directions, and the overlapping segments determine the order of the PCR fragments, thereby selectively producing the final long DNA product.

Multiple choice

Which of the following vectors is used for preparing genomic libraries of eukaryotes?

  1. pUC7

  2. pSC101

  3. EMBL3

  4. Cosmid vectors

  5. Yeast vectors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is used in case of many lambda vectors, called replacement vectors, insertion of DNA  fragment accompanied with the deletion of  all or a  part of the nonessential segment specifying lysogeny. The vector and the DNA insert sizes are carefully adjusted for an effective selection. Lambda vectors EMBL3 and EMBL4 are used for preparing genomic libraries of eukaryotes.

Multiple choice

Which of the following vector is used for obtaining single stranded copies of cloned of DNA ?

  1. phage M 13 vectors

  2. EMBL3

  3. cosmid vectors

  4. ARS vectors

  5. shuttle vectors
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

is used for obtaining single stranded copies of cloned of DNA which is suited for DNA sequences.They are derived from the 6.4kb genome  of the filamentous  bacteriophage M 13.This phage has a single stranded linear  DNA genome in phage particle which then converts into a double stranded circular intermediate in host cells. 

Multiple choice

What is the effect of insertion of the DNA fragment into pBR322 using restriction enzyme Pst I or Pvu I?

pBR322 is the most widely used plasmid of 4362bp. Its entire sequence is known. It has a replication module of E.coli plasmid, Col E1.This module has been incorporated in many other plasmid vectors since it permits plasmid replication even when chromsome replication and cell division are inhibited by aminoacid starvation or chloramphenicol. It has two selectable markers( tetracycline, tetR  and ampicillin, ampR resistant genes) and only single or unique recognition sites for 12 different restriction enzymes.

  1. The recombinant vector will be resistant to tetracycline but sensitive to ampicillin.

  2. The recombinant vector will be resistant to ampicillin but sensitive to tetracycline.

  3. The recombinant vector will be resistant to both ampicillin and tetracycline.

  4. The recombinant vector will be sensitive to both ampicillin and tetracycline.

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Unique restriction site for restriction enzymes PstI and PvuI IS located within the ampR gene. So, the DNA fragment inserted within the ampR  gene makes it nonfunctional. Bacterial cells containing such recombinant pBR 322 will be unable to grow in the presence of ampicillin but shall be resistant to tetracycline.

Multiple choice

Which of the following vector is obtained by the deletion of the poison sequence of pBR322?

pBR322 has nic-bom region which is responsible for its mobilization.Mobilization refers to the cell to cell transfer of an otherwise conjugative plasmid inside the same cell as former. The nic-bom region also interferes with replication efficiency of extrachromosomal DNA in monkey cells,such prokaryotic sequence are called poison sequences. The poison sequence of pBR322 has been deleted to yield pBR327 .

  1. pSC101

  2. pUC7

  3. M13phages

  4. pAT153

  5. ARS vector
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

deletion between bases 1644 and 2345

Multiple choice

Which of the following vectors has been designed to clone cDNA?

Lambda GT10 is a genetically engineered version of the wild type lambda virus. It has been changed in two important ways in order to make it more useful for molecular biological manipulations. First, a large piece of unnecessary DNA (the stuffer fragment) was removed. This creates room in the genome to clone a piece of foreign DNA (an insert) into the virus, which will then be replicated along with the viral genome. This means that we can use lambda GT10 to amplify a cloned piece of DNA and make many copies of it. Second, lambda GT10 has been modified to only use the lytic cycle when it is grown in an appropriate host. For this reason, when you grow the phage on a lawn of the appropriate strain of E. coli, the phage will lyse the bacteria and you will see a clear spot on the cloudy film of E. coli

  1. λgt 10

  2. ARS vector

  3. The shuttle vector

  4. The cosmid vector

  5. Phasmid vector
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

λgt 10  and λgt11 have been designed to clone cDNA.

Multiple choice

Two purified DNA samples A and B contain equal number of base pairs. Each of these DNA samples has one site each for EcoRI and BamHI restriction enzymes. Complete digestion with both the enzymes yielded 3 DNA bands and 2 DNA bands respectively for A and B upon electrophoresis of the digestion products. Which one of the following explains the observation?

  1. A is circular DNA and B is linear.

  2. B is circular DNA and A is linear.

  3. A is circular DNA and B could be linear or circular.

  4. B is circular DNA and A could be linear or circular.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

Four identical PCR reactions were carried out in tubes named I, II, III and IV. Besides the usual mix of dNTPs, each of the tubes respectively contained $\gamma$-32P dATP, $\beta$-32P dATP, $\alpha$-32P dATP and $\alpha$-32P rNTP. Which one of the tubes will have radiolabeled PCR product?

  1. Tube I

  2. Tube II

  3. Tube III

  4. Tube IV
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During PCR, DNA polymerase adds dNTPs to the growing strand by utilizing the alpha phosphate and releasing pyrophosphate from the incoming dNTP. Therefore, only alpha-32P dATP will be incorporated into the newly synthesized PCR product, whereas beta and gamma phosphates are cleaved off during the reaction.

Multiple choice

The mutagen ethidium bromide acts as a

  1. Deaminating agent

  2. Intercalating agent

  3. Alkylating agent

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

Ethidium bromide is a planar molecule that inserts itself between adjacent base pairs in the double helix of DNA, acting as a classic intercalating agent. This distorts the DNA helix and can cause frameshift mutations during replication.

Multiple choice

Which of the following statements are TRUE on DNA delivery methods during plant transformation? P. Single stranded nicks are made in T-DNA border repeat by the VirD1, VirD2 and VirD3 protein complex. Q. virA gene products form the export apptratus on the membrane for the transfer of T-DNA. R. Gold/Tungsten particles are used as microprojectiles in biolistic method. S. Acceleration of DNA-coated microprojectiles is carried out with compressed CO2.

  1. P, S

  2. R, S

  3. P, R

  4. Q, S
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice

Four Hfr strains of E. coli were generated from the same F strain. The Hfr strains donated markers in the following order Straini: DQWMT; Strain 2: AXPTM; Strain 3: BNCAX; Strain 4: BDQWM The order of the markers in the original F+ strain is

  1. DQWMTPXACNB

  2. AXPTMDQWBNC

  3. BNCAXPTMDQW

  4. BDQWMNCAXPT
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

By overlapping the sequences provided by the four Hfr strains, one can reconstruct the circular order of the markers. Aligning the sequences reveals the circular sequence DQWMTPXACNB.

Multiple choice

An actively growing culture (20 ml) of E. coli (1 $\times$ 105 per ml) was mixed with a total of 100 T4 phage particles, grown further for 40 min and mixed with a few drops of chloroform. Under the conditions used, the generation time of F. coli is 30 min, the infection cycle of phage T4 is 20 min, and the burst size is 100. Assuming that each infection was a successful one, how many plaque forming units would you expect at the end of the experiment?

  1. 104

  2. 103

  3. 105

  4. 106
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

In which one of the following organisms, it is easiest to distinguish mutations on adjacent base pairs of DNA through genetic recombination experiments?

  1. Bacteriophages

  2. Yeast

  3. Escherichia coli

  4. Bacillus subtilis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bacteriophages have very small genomes and high recombination rates, allowing for the mapping of mutations at the level of individual base pairs. This fine-scale genetic mapping is much more difficult in larger, more complex organisms like E. coli or yeast.