Biology

DNA and Genetics

1,095 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 among the following statements regarding the lac operon is incorrect?

  1. The lac repressor is a trimer of identical subunits.

  2. The repressor is an allosteric protein.

  3. Specific control of the lac genes depends on the availability of the substrate lactose to the bacterium.

  4. Transcription of all genes starts with the binding of the enzyme RNA polymerase.

  5. The first control mechanism is the regulatory response to lactose.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The lac repressor is a tetramer of identical subunits. Each subunit contains a helix-turn-helix (HTH) motif capable of binding to DNA. The operator site where repressor binds is a DNA sequence with inverted repeat symmetry.

Multiple choice

Both bacteria and eukaryotes repair DNA by _____________________ process.

  1. genetic drift

  2. germline mutation

  3. gene expression

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

Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method of DNA repair in both bacteria and eukaryotes.

Multiple choice

The double-strand breaks are mainly repaired by

  1. homologous recombination

  2. non-homologous end joining

  3. chromosomal translocation

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

Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is most widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks.

Multiple choice

The structure acting as conjugation canals in bacterial cell is

  1. Nucleoid

  2. Pili

  3. Flagella

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

These are extremely minute hair like appendages. They are made up of a protein called pilin. They help in the attachment of a bacterial cell. They also act as conjugation canals through which DNA of one cell passes into the other.

Multiple choice

Which among the following statements regarding the differential extraction of DNA is incorrect?

  1. This method is used in the extraction of DNA from vaginal epithelial cells.

  2. Differential extraction disrupt the peptide bonds present in the coating of the sperm cell.

  3. Through this process, the DNA from two different types of cells can be extracted without mixing their contents.

  4. The first part of the differential lysis is carried out under mild conditions to gain the female DNA.

  5. Due to the high yield of DNA, the chance of a successful DNA-profile by downstream analysis is significantly increased.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Differential extraction uses a chemical called dithiothreitol (DTT) to disrupt the sulfur bonds in the coating of the sperm cell in order to extract its DNA.

Multiple choice

Which among the whole-genome sequencing methods has the capability to target multiple genes simultaneously?

  1. Polymerase chain reaction

  2. Molecular inversion probe

  3. Hybrid capture

  4. In-solution capture

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

Polymerase chain reaction (PCR) is a technology to amplify specific DNA sequences. It uses a single stranded piece of DNA as a start for DNA amplification. Uniplex PCR uses only one starting point (primer) for amplification and multiplex PCR uses multiple primers. This way multiple genes can be targeted simultaneously.

Multiple choice

Zero-mode waveguides illuminates the process of translation. It is used by _______________ type of DNA sequencing.

  1. shotgun sequencing

  2. single cell sequencing

  3. single molecule fluorescent sequencing

  4. single molecule real time sequencing

  5. magnetic sequencing
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Single molecule real time sequencing  is a parallelized single molecule DNA sequencing by synthesis technology. It utilizes the zero-mode waveguide (ZMW). A single DNA polymerase enzyme is affixed at the bottom of a ZMW with a single molecule of DNA as a template.

Multiple choice

Which among the following DNA-modifying enzymes is regarded as a type of molecular motor?

  1. DNA ligases

  2. Topoisomerases

  3. Helicases

  4. Polymerases

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

Helicases are proteins that are a type of molecular motor. They use the chemical energy in nucleoside triphosphates, predominantly ATP, to break hydrogen bonds between bases and unwind the DNA double helix into single strands. These enzymes are essential for most processes where enzymes need to access the DNA bases.