Biology

Molecular Biology and Genetics

985 Questions

Molecular biology and genetics explore the structure and function of DNA, RNA, genetic mutations, and heredity. Understanding these building blocks of life is essential for most biology examinations. Review these practice questions to test your molecular genetics knowledge.

DNA structure and basesGenetic mutationsNucleic acids compositionDNA sequencing and replication

Molecular Biology and Genetics Questions

Multiple choice

The mutation due to the insertion or deletion of nucleotides is known as

  1. frameshift mutation

  2. neutral mutation

  3. silent mutation

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

Frameshift mutation is a mutation caused by insertion or deletion of a number of nucleotides that is not evenly divisible by three from a DNA sequence. Due to the triplet nature of gene expression by codons, the insertion or deletion can disrupt the reading frame, or the grouping of the codons, resulting in a completely different translation from the original. The earlier in the sequence the deletion or insertion occurs, the more altered the protein produced is.

Multiple choice

The process by which extra nucleotides are added into the DNA molecule is known as

  1. point mutation

  2. insertions

  3. deletions

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

Insertions add one or more extra nucleotides into the DNA. They are usually caused by transposable elements, or errors during replication of repeating elements, e.g. AT repeats. Insertions in the coding region of a gene may alter splicing of the mRNA (splice site mutation), or cause a shift in the reading frame (frameshift), both of which can significantly alter the gene product.

Multiple choice

Which among the following is a nuclease enzyme?

  1. Hind III

  2. Maltase

  3. Pepsin

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

Hind III is a type II site-specific deoxyribonuclease restriction enzyme isolated from Haemophilus influenzae that cleaves the palindromic DNA sequence AAGCTT in the presence of the cofactor Mg2+ via hydrolysis. The cleavage of this sequence between the AA's results in 5' overhangs on the DNA called sticky ends.

Multiple choice

Which kind of mutation is induced by base analog 5-bromouracil?

  1. Insertion mutation

  2. Transversion mutation

  3. Transition mutation

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

5BU induces transition mutation in DNA. When a nucleotide containing 5-bromouracil is incorporated into the DNA, it is most likely to pair with adenine. However, it can spontaneously shift into another isomer which pairs with a different nucleobase, guanine. If this happens during DNA replication, a guanine will be inserted as the opposite base analog. This results in a change in one base pair of DNA, specifically a transition mutation.

Multiple choice

Which of the following form(s) DNA cross links to induce mutation?

  1. Ochratoxin A

  2. Psoralens

  3. Ethidium bromide

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

Psoralens are natural compounds (furocoumarins) present in plants. They form DNA cross links to induce mutation. The crosslinking reaction by psoralens targets TA sequences intercalating in DNA and linking one base of the DNA with the one below it.

Multiple choice

Which among the following methods of sequencing DNA produces information about both identity and location of nucleotide sequences within the genome of an individual?

  1. Transposon sequencing

  2. Deep sequencing

  3. Exome sequencing

  4. Positional sequencing

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

Positional sequencing is a method of sequencing DNA that simultaneously generates information about both identity and location of nucleotide sequences. The method involves detecting the location of sequence specific recognition events (e.g., such as hybridization of probes of known sequence) on single DNA molecules.

Multiple choice

DNA microarray analysis is one of the fastest-growing new technologies in the field of genetic research. Which among the following statements does not characterizes the process of DNA microarray?

  1. DNA microarrays involves the hybridization between two DNA strands.

  2. DNA microarrays can be used to detect single nucleotide polymorphisms.

  3. DNA microarray experiment can accomplish many genetic tests in parallel.

  4. Probe-target hybridization is usually detected and quantified by detection of fluorophore-, platinum -, or chemiluminescence-labeled targets.

  5. A DNA microarray is a collection of microscopic DNA spots attached to a solid surface.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target.

Multiple choice

Which of the following statements is/are true regarding genome?

  1. The term ‘genome’ was given by Hans Winkler.
  2. Genome size is the total number of DNA base pairs in one copy of a diploid genome.
  3. Bacteriophage MS2 was the first sequenced DNA-genome. Select the correct answer using codes given below:

  1. Only 1

  2. Only 2

  3. Only 3

  4. Both 1 and 2

  5. Both 2 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The term ‘genome’ was given by Hans Winkler, professor of botany at the University of Hamburg, Germany.

Multiple choice

Full form of DNA is

  1. deoxyribonucleic acid

  2. dioxyribonucleic acid

  3. diribonucleic acid

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

DNA stands for deoxyribonucleic acid, which is the molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known organisms. Option B is incorrect because it should be 'deoxy' not 'dioxy'. Option C is missing 'oxy' and option D is missing 'oxy' as well.

Multiple choice

Define Chromosomal DNA.

  1. Genomic DNA of prokaryotic organisms complexed with protein

  2. Genomic DNA of eukaryotic organisms complexed with protein

  3. Genomic DNA of nearly all prokaryotic and eukaryotic organisms is complexed with protein to form chromosomal DNA

  4. Single stranded RNA

  5. A fragment of DNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is the complete definition for chromosomal DNA.

Multiple choice

What is the melting temperature (Tm) of DNA?

  1. The temperature at which 50% of the DNA is melted is termed the melting temperature or Tm.

  2. The temperature at which 100% of the DNA is melted is termed the melting temperature or Tm.

  3. The temperature at which DNA starts melting is termed the melting temperature or Tm.

  4. The temperature at which DNA is denatured is termed the melting temperature or Tm.

  5. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is the correct answer. At this temperature, 50% of the DNA is melted.