Molecular Biology MCQs | BIO302 MCQs | Set 2
Molecular Biology MCQs | BIO302 MCQs | Set 2
MCQs (Multiple Choice Questions)
1) Which one of the following is not an ionizing radiation?
a) X-rays
b) Ultraviolet light
c) Gamma rays
d) `\beta` rays
Correct Answer:
The correct answer is 'b'.
Explanation:
The term "ionizing radiation" refers to radiation that has enough energy to remove tightly bound electrons from atoms, creating ions. Out of the options provided, Ultraviolet light is not considered ionizing radiation.
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2) Hydrolytic deamination of cytosine is estimated to take place about___.
a) 1000 to 5000 times a day in a mammalian cell
b) 100 to 500 times a day in a mammalian cell
c) 10 to 50 times a day in a mammalian cell
d) 1 to 5 times a day in a mammalian cell
Correct Answer:
The correct answer is 'b'.
Explanation:
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3) Pyrimidine dimers are formed by____
b) Infra red
d) nuclear radiation
Correct Answer:
The correct answer is 'a'.
Explanation:
Pyrimidine dimers are formed by UV radiation. When DNA is exposed to UV radiation, particularly in the UVB range (between 280 and 315 nm), adjacent pyrimidine bases (such as thymine or cytosine) can become cross-linked, forming what are known as pyrimidine dimers. These DNA lesions can interfere with DNA replication and transcription if not adequately repaired, potentially leading to mutations and other cellular issues.
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4) In long patch repair, how many nucleotides are repaired
a) 1
b) 4-6
c) 2-8
d) 10-14
Correct Answer:
The correct answer is 'c'.
Explanation:
In long patch repair, a stretch of 2-8 nucleotides is synthesized to replace the damaged region of DNA. This is in contrast to short patch repair, where only a single nucleotide is replaced.
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5) There are three human MutS homologs______.
a) MSH1, MSH2, MSH3
b) MSH2, MSH3, MSH4
c) MSH2, MSH3, MSH6
d) MSH2, MSH3, MSH5
Correct Answer:
The correct answer is 'c'.
Explanation:
The three human MutS homologs are MSH2, MSH3, MSH6. These are proteins involved in DNA mismatch repair in humans.
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6) RNA polymerase performs essentially the same reaction in the cells from bacteria to human that is the synthesis of _______ .
a) cDNA
b) DNA
c) RNA
d) DNA, RNA and Cdna
Correct Answer:
The correct answer is 'c'.
Explanation:
RNA polymerase performs the synthesis of RNA in both bacterial and human cells. It catalyzes the formation of RNA molecules using a DNA template, a process known as transcription.
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7) Cells infected with phage _____ provide the ideal system to find the true template for protein synthesis
a) T4
b) P4
c) S4
d) L4
Correct Answer:
The correct answer is 'a'.
Explanation:
Cells infected with phage T4 provide an ideal system to find the true template for protein synthesis. The T4 bacteriophage is commonly used in molecular biology and genetic studies, providing an excellent system to understand the process of protein synthesis and the identification of the true template for this synthesis.
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8) ________ are similar enough to the proper bases to get taken up by cells converted into nucleoside triphosphate and incorporated into DNA during replication.
a) Interclating agents
b) Base analogs
c) Amino acid
analogs
d) None of these
Correct Answer:
The correct answer is 'b'.
Explanation:
Base analogs are similar enough to the proper bases to be taken up by cells, converted into nucleoside triphosphates, and incorporated into DNA during replication. These analogs resemble natural DNA bases and can be integrated into the DNA structure during replication, potentially causing mutations or affecting DNA function due to their similarity to natural bases.
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9) Aflatoxins are produced by_______.
a) Bacteria
b) Virus
c) Fungi
d) Parasites
Correct Answer:
The correct answer is 'c'.
Explanation:
Fungi produce aflatoxins. Aflatoxins are a type of mycotoxin produced by certain molds, especially Aspergillus species, which commonly contaminate food crops such as peanuts, corn, and various nuts. These toxins can have detrimental effects on human and animal health if ingested in high quantities.
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10) What will happen to the DNA exposed to N-methylguanine
a) it will be oxidized
b) it will make dimers of the bases
c) it will lead to production of mono-adduct
d) it will form a basic site
Correct Answer:
The correct answer is 'c'.
Explanation:
Exposure of DNA to N-methylguanine can result in the formation of a mono-adduct. N-methylguanine is a type of DNA lesion where a methyl group is added to the guanine base. This modification alters the normal structure of DNA, creating a mono-adduct, a chemical modification involving the addition of a single molecule to the DNA base, which can interfere with DNA replication and potentially lead to mutations.
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