This set of Agricultural Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Storage of DNA and Handling of Enzymes – Set 2”.
1. What is the required temperature for the storage of assay buffers?
a) -5˚C
b) -10˚C
c) -15˚C
d) -20˚C
View Answer
Explanation: The assay buffers are supplied along with enzymes by the manufacturers and should also be stored at -20˚C. Sterile double distilled water should be used for dilution during the preparation of reaction mixtures.
2. In which year was the term ‘restriction endonuclease’ coined?
a) 1960
b) 1962
c) 1964
d) 1966
View Answer
Explanation: The term ‘restriction endonuclease’ was coined by Lederberg and Meselson to describe the nuclease enzyme that destroys any foreign DN entering the host cell.
3. Restriction endonuclease is also called as _______
a) Molecular knife
b) Target site
c) Cut ends
d) Ligase
View Answer
Explanation: Restriction endonucleases have been classified into three different types viz. type I, type II and type III. In gene manipulation technology, restriction endonucleases are popularly called molecular knives or molecular scissors or molecular scalpels.
4. Type I enzymes interact with an unmodified recognition sequence in double strand DNA.
a) True
b) False
View Answer
Explanation: Restriction enzymes of type I interact with an unmodified recognition sequence in double strand DNA and then attach to log DNA molecule. It then travels between 1000-5000 nucleotides and cleaves only one strand of the DNA at an apparently random site.
5. What is the gap created by type I enzyme during cleaving?
a) 50 nucleotides
b) 75 nucleotides
c) 100 nucleotides
d) 150 nucleotides
View Answer
Explanation: Type I enzyme is not useful for gene manipulation because their cleavage sites are non-specific. Type I enzymes bind to target sites, after which they are fully released from fully methylated sites.
6. Type I enzyme can simultaneously hold two different sites on DNA.
a) True
b) False
View Answer
Explanation: Type I can simultaneously hold two different sites on DNA creating a loop in nucleic acid. The type I restriction enzyme consists of three types of subunit.
7. Which of the following enzymes is used for gene manipulation studies?
a) Type I restriction enzyme
b) Type II restriction enzyme
c) Type III restriction enzyme
d) Type I and III restriction enzyme
View Answer
Explanation: Type II restriction enzymes are used for the gene manipulation studies and unlike type I, they recognize a particular target sequence in a double-strand DNA molecule.
8. Which of the following enzymes cleave DNA at well defined sites?
a) Type I restriction enzyme
b) Type II restriction enzyme
c) Type III restriction enzyme
d) Type I and II restriction enzyme
View Answer
Explanation: Type III restriction enzymes cleave double stranded DNA at well defined sites. They require ATP, Mg2+ ions and have a partial requirement for S-adenosyl-methionine for restriction.
9. What is the approximate number of restriction endonucleases present?
a) 300
b) 325
c) 350
d) 375
View Answer
Explanation: About 350 restriction endonucleases have been isolated from more than 200 bacterial strains. Hence uniform nomenclature is made for these enzymes.
10. Which of the following is not correct regarding enzyme nomenclature (1973)?
a) Each enzyme is named by a two letter code
b) First letter is from the first epithet of the genus name
c) Second letter is a species name
d) Strain number is considered
View Answer
Explanation: A system based on the proposals of Smith and Nathans (1973) has been followed for the most part of the nomenclature. Each enzyme is named by a three letter code.
Sanfoundry Global Education & Learning Series – Agricultural Biotechnology
To practice all areas of Agricultural Biotechnology, here is complete set of 1000+ Multiple Choice Questions and Answers.
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