Engineering Questions with Answers - Multiple Choice Questions

MCQs on Genome Structure

1 - Question

Circular DNAs are negatively supercoiled.
a) True
b) False

View Answer

Answer: a
Explanation: Circular DNAs extant in nature include mitochondrial, bacterial and viral DNA. These are invariably negatively supercoiled i.e. underwound. An underwound DNA has greater number of basepairs per turn of the helix.




2 - Question

Etoposide and doxorubicin, the drugs used in Cancer treatment target the enzyme ___________
a) topoisomerase I
b) topoisomerase II
c) helicase
d) isomerase

View Answer

Answer: b
Explanation: Both these drugs are target DNA in Cancer cells. They bind to topoisomerase II enzyme which prevents the DNA stands from re-ligating and thus causes it to break.




3 - Question

The three-dimensional structure of DNA can be described by _________
a) Vacuum filtration
b) X-ray crystallography
c) Gel electrophoresis
d) Mass spectroscopy

View Answer

Answer: b
Explanation: DNA is a macromolecular formed by the assembly of a large number of atoms. The three-dimensional structure of a DNA can be described by X-Ray diffraction technique.




4 - Question

The haploid set of human chromosomes consist of __________ chromosomes
a) 22
b) 23
c) 24
d) 25

View Answer

Answer: c
Explanation: The human genome is essentially equivalent to all the genetic information that is present in a single haploid set of chromosomes, containing 22 autosomes and 2 sex chromosomes X and Y.




5 - Question

The process of DNA melting can be monitored by a change in ___________
a) absorbance
b) pH
c) concentration
d) color

View Answer

Answer: a
Explanation: DNA melting is the process where DNA is dissolved in saline solution and the temperature is increased to initiate the process of separation. When DNA separates into its component strands, the absorbance of dissolved DNA increases and this serves as a parameter for monitoring the process.




6 - Question

The temperature at which the shift in absorbance is half completed is termed as ___________
a) melting temperature
b) denaturation temperature
c) shifting temperature
d) absorbance temperature

View Answer

Answer: a
Explanation: When the DNA separates into two of its constituent strands. The hydrophobic interactions that result from base stacking are greatly reduced, which changes the electronic nature of the bases and increases their absorbance of ultraviolet radiation. The temperature at which the shift in absorbance is half completed is termed as the melting temperature Tm.




7 - Question

Higher the concentration of GC content, lower the Tm.
a) True
b) False

View Answer

Answer: b
Explanation: There are three hydrogen bonds between GC pairs and two between the AT pairs. The extra hydrogen bond present leads to increase stability and an overall increase in Tm when the GC (%G + %C) content is higher.




8 - Question

DNA renaturation was first realized in the year ___________
a) 1940
b) 1950
c) 1960
d) 1970

View Answer

Answer: c
Explanation: In the year 1960 Julius Marmur and co-workers at the Harvard University found that slowly cooling the solution of bacterial DNA that had been thermally denatured, the DNA renatures and the properties of a double helix are restored.




9 - Question

Reannealing or renaturation of the DNA is the basis of the technique ___________
a) paper chromatography
b) ultraviolet spectroscopy
c) nucleic acid hybridization
d) gel electrophoresis

View Answer

Answer: c
Explanation: Reannealing is the process of restoration of DNA helical structure after they have been denatured. This characteristic of the genetic material forms the basis of nucleic acid hybdridization.




10 - Question

For three different samples of DNA with same concentration, the rate of annealing will depend on __________
a) pH
b) absorbance
c) temperature
d) genome size

View Answer

Answer: d
Explanation: The rate of annealing will depend upon the size of genome. Smaller the genome, greater will be the rate of annealing.




11 - Question

. Percentage of highly repeated DNA sequences in a genome is __________
a) 1-10 %
b) 15-20%
c) 20-30%
d) 35-40%

View Answer

Answer: a
Explanation: The highly repeated fraction consists of sequences that are present in at least 105 copies per genome. Such sequences make up about 1 to 10% of the total DNA.




12 - Question

Which of the following type of DNA sequences for the basis of DNA fingerprinting?
a) Satellite DNA
b) Minisatellite DNA
c) Microsatellite DNA
d) Tandem sequences

View Answer

Answer: b
Explanation: Minisatellite DNA range from 10 to 100 base pairs in length and are found in clusters containing 3000 repeats. Because of unequal crossing over, these sequences are highly unstable and polymorphic. Because the minisatellite DNA can vary from person to person, it forms the basis of technique used for criminal or paternity cases, DNA fingerprinting.




13 - Question

. Which type of DNA have been used to analyze relationship between different human populations?
a) Circular DNA
b) Mitochondrial DNA
c) Minisatellite DNA
d) Microsatellite DNA

View Answer

Answer: d
Explanation: Also called short tandem repeats, Microsatellites are short repeats of 2-6 bp of DNA that are present throughout the genome and have variability among populations. They are therefore used in DNA fingerprinting.




14 - Question

In situ hybridization was aimed at determining the location of _______
a) satellite DNA
b) nucleus
c) mitochondria
d) autosomes

View Answer

Answer: a
Explanation: In 1969 Mary Lou Pardue and Joseph Gall of Yale University developed the technique of in situ hybridization to determine the location of satellite DNA.




15 - Question

. Moderately repeated DNA sequences can vary from _______ percent of the total DNA.
a) 10-20
b) 20-80
c) 20-50
d) 50-80

View Answer

Answer: b
Explanation: Moderately repeated DNA sequences can vary from 20 to more than 80 percent of the total DNA. They included sequences that code for known gene products like RNAs and proteins.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners