This set of Genetic Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Genomic Libraries”.
1. Libraries can broadly be classified into how many types?
Explanation: Libraries can be classified basically into two types- genomic libraries and cDNA libraries. Genomic libraries are constructed from the whole genome of the organism. cDNA libraries are constructed from the DNA copies of RNA sequences.
2. Choose the correct statement for genomic libraries.
a) Genomic libraries include the representation of the whole genome of the organism
b) Sequences such as telomeres are also represented
c) Telomeres can be readily cloned
d) The larger the size of insert of genomic DNA in recombinants, the more is the number of recombinants required to represent the genome in the library
Explanation: Genomic libraries include the representation of whole organism. Sequences such as telomeres can’t be represented in the genomic libraries because they can’t be readily cloned. The larger size of insert of genomic DNA in recombinants, less number of recombinants is required to represent the genome in the library.
3. Choose the incorrect statement for preparation of genomic libraries.
a) The first step is isolation of genomic DNA
b) Physical damage to the DNA should be avoided
c) If a nuclear DNA library is to be constructed, organelle DNA is to be removed
d) For the construction of organelle library, organelle DNA is purified from the nuclear DNA
Explanation: For the preparation of genomic libraries, the first step is isolation of genomic DNA. Physical damage to the DNA should be avoided and DNA of high molecular weight should be obtained. For the construction of nuclear DNA library, organelle DNA (DNA which is included in mitochondria and chloroplast), is not removed. It is so because they are very less in amount in comparison to nuclear DNA. For the construction of organelle library, organelle DNA is purified from the nuclear DNA.
4. The various steps for construction of libraries are:
i) Fragmentation of DNA
ii) Isolation of genomic DNA
iv) Ligation and introduction to the host
v) Vector preparation
The correct order of construction of libraries is (In the order of starting to ending) :
Explanation: Firstly, the isolation of genomic DNA is carried out. It is followed by the fragmentation of DNA. Then the vector preparation is done, which is followed by the ligation and introduction to the host. The final step is the amplification of the recombinants.
5. Complete digestion is preferred over partial digestion for the fragmentation of DNA. The given statement is true or false?
Explanation: Partial digestion is preferred over complete digestion. It is so because if complete digestion is carried out, it is not necessary that all the fragments are represented. Thus partial digestion is preferred over complete digestion.
6. To avoid ligation of separate DNA fragments, which of the enzyme is used?
Explanation: To avoid ligation of separate DNA fragments, phosphatase is used. By the use of phosphatase, terminal phosphate groups are removed and thus ligation is not done. Joining of separate fragments is avoided because it would lead to formation of non-contiguous DNA.
7. Vector and insert are mixed, ligated and packaged and introduced into the host by:
d) transformation and infection both
Explanation: Vector and insert are mixed, ligated and packaged into the host by transformation and infection both.
8. Libraries using phage cloning vectors are often kept as:
a) unpackaged phage
b) packaged phage
c) both packaged and unpackaged phage
d) both packaged and unpackaged phage are used but packaged is favoured
Explanation: Libraries using phage cloning vectors are often kept as packaged phage. This can be plated out on appropriate hosts when needed.
9. Libraries constructed in plasmid vectors can be kept as:
a) plasmid containing cells
b) naked DNA
c) both plasmid containing cells and naked DNA
d) naked DNA is preferred over plasmid containing cells
Explanation: Libraries constructed in plasmid vectors can be kept as both plasmid containing cells and naked DNA. The naked DNA can be transformed into the host as required.
10. During storage there are chances of degradation of DNA. Larger fragments are having more chances of being got lost. The given statement is true or false?
Explanation: During storage there are chances of degradation of DNA and the larger fragments are at greater risk of being lost. And thus average insert size will gradually fall.
Sanfoundry Global Education & Learning Series – Genetic Engineering.
To practice all areas of Genetic Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.