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

Which characters should be possessed by a plasmid for rDNA technology?

  1. Genes related to ori-restriction site

  2. Genes of ori - insulin gene - restriction site

  3. Colicin gene - ori - restriction site

  4. Cloning gene - colicin gene - ori

  5. Ori - colicin gene - insulin gene
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ori - for origin of replication, is a restriction site for insertion of desired gene.

Multiple choice

Which among the following is/are used by viruses to insert their genetic material into the host genomes?

  1. Inverted repeat

  2. Direct repeats

  3. Long terminal repeats

  4. Tandem repeats

  5. Interspersed repetitive DNA elements
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Long terminal repeats are identical sequences of DNA that repeat hundreds or thousands of times found at either end of retrotransposons or proviral DNA formed by reverse transcription of retroviral RNA. They are used by viruses to insert their genetic material into the host genomes.

Multiple choice

The inserted gene may damage the function of one of the host's genes. Which among the following insertion causes loss of protein function in host genes?

  1. Insertion between promoter and upstream enhancers

  2. Insertion in a translated region

  3. Insertion in an intron

  4. Insertion in 5' untranslated region

  5. Insertion in promoter
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Insertion in an intron altered splicing pattern/splicing failure. It usually results in protein truncation or the production of inactive mis-spliced products, although more complex effects are common.

Multiple choice

In genetics, the process of gene conversion is regarded as the mechanism responsible for the separation of species. Which among the following statements does not characterise gene conversion?

  1. Conversion of one allele to the other is often due to base mismatch repair during hetrozygous recombination.

  2. Meiotic recombination is initiated through formation of a double-strand break.

  3. One of these 3’ single stranded DNA segments forms an intermediate.

  4. In Synthesis Dependent Strand Annealing (SDSA), there is information exchange but not physical exchange.

  5. Gene conversion may occur during recombinational repair involving a DHJ.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conversion of one allele to the other is often due to base mismatch repair during homologous recombination: if one of the four chromatids during meiosis pairs up with another chromatid, as can occur because of sequence homology, DNA strand transfer can occur followed by mismatch repair. This can alter the sequence of one of the chromosomes, so that it is identical to the other.

Multiple choice

A transposable element, TE is a DNA sequence that can change its position within the genome of an individual. Which among the following statements regarding the transposable element is incorrect?

  1. Mu phage transposition is the best known example of replicative transposition.

  2. A helitron is a TE found in prokaryotes.

  3. The most common form of transposable element in humans is the Alu sequence.

  4. Transposons in bacteria usually carry an additional gene for function.

  5. One family of TEs in the fruit fly Drosophila melanogaster are called P elements.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A helitron is a TE found in eukaryotes that are thought to replicate by a rolling-circle mechanism.

Multiple choice

Mo is a part of enzyme

  1. reverse transcriptase

  2. restriction endonuclease

  3. hexokinase

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

Nitrogenase is a molybdenum containing enzyme.

Multiple choice

Which of the following statements is/are FALSE?

I. Insertion or deletion of a nucleotide in a class of mutation resulting in a sequence of codon that makes nonsensical polypeptide chain is called frame shift mutation. II. The enzymes involved in interconversion of relaxed and super coiled forms of DNA molecules are called topoispmerases. III. DNA foot printing technique is usually used to identify the site for termination of transcription processes.

  1. Only I

  2. Only II

  3. Only III

  4. Both I and II

  5. Both II and III
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Correct answer. Statement III is a false statement. DNA foot printing technique is usually used to identify the sites of DNA where DNA binding proteins attach.

Multiple choice

Assertion: Transposition starts by forming a strand transfer complex in which the transposon is connected to the target site through one strand at each end. Reason: Replicative Transposition Proceeds through a Cointegrate.

  1. A and R both are correct and R is correct explanation of A.

  2. A and R both are correct and R is not correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A and R both are correct and R is not correct explanation of A. Transposition starts by forming a strand transfer complex in which the transposon is connected to the target site through one strand at each end. Replicative Transposition Proceeds through a Cointegrate. Replication of a strand transfer complex generates a cointegrate, which is a fusion of the donor and target replicons. The cointegrate has two copies of the transposon, which lie between the original replicons. Recombination between the transposon copies regenerates the original replicons, but the recipient has gained a copy of the transposon.

Multiple choice

Which of the following statements are not true?

  1. Transposition occurs by only nonreplicative mechanism.
  2. Homologous recombination between multiple copies of a retrotransposon causes rearrangement of host DNA.
  3. Homologous recombination between the repeats of retrotransposon may lead to imprecise excision.
  4. Imprecise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome.

  1. Only 1 and 2

  2. Only 1 and 3

  3. Only 1 and 4

  4. Only 2 and 3

  5. Only 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Transposition occurs by both Replicative and Nonreplicative Mechanisms. All transposons use a common mechanism in which staggered nicks are made in target DNA, the transposon is joined to the protruding ends, and the gaps are filled. The order of events and exact nature of the connections between transposon and target DNA determine whether transposition is replicative or nonreplicative. Precise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome. Imprecise excision occurs when the transposon removes itself from the original insertion site, but leaves behind some of its sequence.