Engineering Questions with Answers - Multiple Choice Questions
MCQs on Genetic Recombination – Transformation
Who discovered transformation?
a) Albert Einstein
b) Robert Hook
c) Fred Griffith
d) Kary Mullis
Explanation: Fred Griffith discovered Transformation in the year 1928. This is a way in which DNA can be moved between different bacteria. It is the uptake of the naked DNA molecule from a medium. There will be a donor bacterium and a recipient bacterium.
For the process of transformation to take place a bacterial cell must be in a state of ____________
Explanation: Transformation is the direct uptake of the genetic material from the surrounding of a cell. For the transformation to take place a cell has to be competent. Transformation is the one if the three processes of horizontal gene transfer. In its exogenous gene can pass from one bacterium to other.
Transformation with micro injection is which kind of transformation?
Explanation: The transformation carried out using a micro injection falls under the physical transformation category. The physical or mechanical ways are electroporation, microinjection, particle bombardment, sonoporation, laser-induced, bead transfection. The biological method is using various viral vectors for the transfer of DNA.
. When does S. pneumoniae becomes competent for transformation?
a) Lag phase
b) Log phase
c) Exponential phase
d) Stationery phase
Explanation: For transformation to occur every cell has to be competent. Competency is dependent on several conditions. Bacteria need to be on certain stage of growth such as S pneumoniae will be competent only on the exponential phase. When the population will be reaching 107 to 108 cells per ml.
We require cell-free DNA for transformation to take place.
Explanation: Transformation is the process whereby cell-free or naked DNA containing a limited amount of genetic information is transferred from one bacterial cell to another. If there is Cell it may be difficult for the transformation process to be carried out swiftly. Thus, we required a cell-free DNA solution.
Which of the following things was identified as the transforming principle?
Explanation: Griffith showed in his experiment that DNA was the transforming principle that transformed the living rough bacteria into pathogenic smooth ones. He used two types of bacteria one with rough membrane and other with a smooth membrane.
What should be the minimum weight of DNA that is required for a successful transformation?
a) 1000 Daltons
b) 100,000 Daltons
c) 300,000 daltons
d) 8 million daltons
Explanation: Molecular weights of DNA in the range of 300,000 to 8 million daltons have been shown to result in successful transformation. Various vectors have been manufacture including HAC, BAC, YAC which can transfer bigger pieces of genomes.
Which enzyme cleaves the DNA?
Explanation: After a competent cell binds to a double stranded moderately large DNA, the donor fragments starts competing with each other. The DNA is then cleaved by endonucleases to form small double stranded fragments of about 5 to 15 kilo base.
In which of the following organism transformation occurs by the help of membrane vesicles?
a) S. pneumoniae
b) H. influenzae
c) E. colli
d) M. tuberculosis
Explanation: Haemophilus don’t produce a competence factor thus it donot become competent. It take up DNA from closely related species. Ds DNA, complexed with other proteins is then taken in membrane vesicles.
. Artificial transformation in the laboratory is carried out by which of the chemical?
a) Sodium chloride
b) Magnesium chloride
c) Calcium chloride
d) Potassium chloride
Explanation: In laboratory artificial transformation is done by treatment of the cells using calcium chloride. This technique also makes the membranes more permeable to the uptake DNA. We can use this technique with species which are naturally competent.
It is tough to transform with plasmid DNA.
Explanation: Transformation of bacteria using plasmid DNA is easier. Since plasmid DNA don’t get easily degraded as linear fragments and can easily replicate in the host. This method is more commonly used for the introduction of recombinant DNA into bacterial cells.
. Which of the following path of transformation leads to the lysis of the parent cell?
c) Lysogenic and lytic pathway
Explanation: After the phage infection, the phage DNA will multiply inside the host cell. The replicating DNA will produce all the kinds of proteins which a phage needs and then phage heads, tails and DNA assembles into progeny phage. After that the lysis of the parent cell occurs.
. In which phase of growth does the recipient cell take up the donor DNA?
a) Lag phase
b) Early logarithmic phase
c) Late logarithmic phase
d) Stationary phase
Explanation: Conditions suitable for uptake of donor DNA into recipient cells occur only during the late logarithmic phase of growth. In the logarithmic phase, the bacteria keep on dividing.
. The DNA uptake process does not require any energy.
Explanation: The uptake process has been found to be an energy-requiring mechanism because it can be inhibited by agents that interfere with energy metabolism. We have to provide the processes with energy, it may be electrical, light, and mechanical.
Which of the following enzymes acts on the DNA after its entry into the cell?
c) Deoxy ribonucleases
Explanation: After DNA entry into a cell, one strand is immediately degraded by deoxy ribonucleases, while the other strand undergoes base pairing with a homologous portion of the recipient cell chromosome.