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 enzyme has the function to join segments of DNA together?

  1. Gyrase

  2. Helicase

  3. None of the above

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

DNA ligase is the enzyme responsible for joining DNA strands together by catalyzing the formation of a phosphodiester bond, which is crucial for sealing nicks in the sugar-phosphate backbone during replication and repair.

Multiple choice

During the polymerase chain reaction, heat is used to

  1. break covalent bonds

  2. break hydrogen bonds

  3. accelerate chemical processes

  4. anneal DNA primers
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the denaturation step of PCR, high temperatures are used to break the relatively weak hydrogen bonds holding the two complementary DNA strands together, separating them without damaging the stronger covalent bonds of the backbone.

Multiple choice

Where are telomeres located?

  1. At the end of the chromosome

  2. On the leading strand

  3. At the replication fork

  4. on prokaryotic plasmids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Telomeres are repetitive nucleotide sequences found at the very ends of linear eukaryotic chromosomes, serving to protect the chromosome ends from degradation and fusion.

Multiple choice

An actively dividing culture of E. coli with radioactive THYMINE; daughter cells would have

  1. one daughter cell radioactive, not the other

  2. DNA in both daughter cells would be radioactive

  3. neither of the daughter cells would be radioactive

  4. all four bases of the DNA would be radioactive
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA replication is semi-conservative. Each daughter cell receives one original strand and one newly synthesized strand. Since the thymine in the medium is radioactive, the new strands in both daughter cells will incorporate it, making both cells radioactive.

Multiple choice

Continuous elongation of a new DNA strand along one strand of DNA

  1. requires the action of DNA ligase as well as polymerase

  2. occurs b/c DNA ligase can only elongate 3' → 5' direction

  3. occurs on the LEADING strand

  4. occurs on the LAGGING strand
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The leading strand is synthesized continuously in the direction of the replication fork movement, while the lagging strand is synthesized discontinuously.

Multiple choice

Transformation involves

  1. uptake of external genetic material, one bacteria to another

  2. creation of a strand of RNA from a DNA molecule

  3. infection of bacterial cells by phage

  4. replication of DNA along the lagging strand
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Transformation is the process by which a bacterium takes up naked DNA from its environment and incorporates it into its own genome.

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

The number of linkage group in E.coli is/are

  1. 4

  2. 2

  3. 1

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

The number of linkage groups equals the number of chromosomes in the basic set. The number of linkage groups in an organism is equal to the haploid number of its chromosomes. Example - In Drosophila, the haploid number is n = 4, so linkage group is 4. But the number of linkage group is prokaryotes (bacteria, like E. coli) is one. This is because bacteria being prokaryotes have only a single circular chromosome.

So, the correct answer is '1'.

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Which enzyme is responsible for linking the fragments of DNA?

  1. DNA polymerase III

  2. Endonuclease

  3. DNA polymerase I

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

DNA Ligase is the enzyme which helps in joining the fragments of DNA, basically, it acts as a glue. In the given options endonuclease helps in cutting the DNA into fragments it cleaves the polynucleotide chain by acting on the nucleotides by breaking the hydrogen bonds between them, whereas DNA polymerases synthesize the DNA molecule from deoxyribonucleotides. So, the correct answer is "DNA ligase".

Multiple choice biology health and diseases non-infectious diseases non infectious diseases categories of diseases

Which protein is called "guardian of genome"?

  1. $P$ $53$
  2. Cyclin $D$
  3. $CDK$ $4$
  4. $Rb$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

p53 is a protein is known as  "guardian of genome" because it regulates cellular apoptosis and cellular growth to maintain the integrity of the human genome. It is also known as policeman of oncogenes because it suppresses the mutation and prevents oncogenesis.

So, the correct answer is option A.