Quiz Online 2 Working With Nucleic Acids

The statement is true because gene manipulation in biology does indeed require facilities for the growth, containment, and processing of different types of cells and organisms. These facilities are necessary to create the conditions needed for manipulating genes and studying their effects. Without these facilities, it would be difficult to conduct research and experiments in gene manipulation.

When ethanol is added to a DNA solution in a ratio of 2:1 by volume, in the presence of 0.2 M salt, it causes the nucleic acids to come out of solution. This is because ethanol disrupts the hydrogen bonding between the DNA molecules, leading to their precipitation. The presence of salt helps to neutralize the negative charges on the DNA molecules, further promoting their aggregation and precipitation. Therefore, the statement "ethanol causes the nucleic acids to come out of solution" is true.

Radiolabelling is a technique used to attach a radioactive label to a molecule, such as nucleic acids. This allows researchers to track and study the molecule's behavior in experiments. In the case of nucleic acids, radiolabelling is commonly used in hybridization experiments, where the labeled nucleic acids are used to detect and bind with complementary sequences. Therefore, the statement that the application of radiolabelling is in the production of highly radioactive nucleic acid molecules for use in hybridisation experiments is true.

Ribonuclease (RNase) is the correct answer because it is an enzyme that specifically digests RNA. In a DNA preparation, if there is unwanted RNA present, RNase can be used to selectively break down the RNA molecules, leaving behind the DNA. This allows for a pure DNA sample to be obtained for further analysis or experiments. Polynucleotide kinase, DNA polymerase I, and deoxyribonuclease I (DNase I) are not suitable for digesting RNA in a DNA preparation.

Labelling by primer extension is a technique where random oligonucleotides are used to initiate the synthesis of a DNA strand by DNA polymerase. This technique is commonly used in molecular biology and genetic research to label DNA fragments for various applications such as DNA sequencing or DNA hybridization studies. Therefore, the given answer "TRUE" is correct as it accurately describes the process of labelling by primer extension.

DNA polymerase I is an enzyme that plays a crucial role in DNA replication. It is responsible for catalyzing the strand-replacement reaction, where it removes the RNA primer and replaces it with DNA nucleotides. This process is necessary for the synthesis of a continuous DNA strand. Therefore, the statement that DNA polymerase I catalyzes a strand-replacement reaction that incorporates new dNTPs into the DNA chain is true.

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Labelling of nucleic acids is not a basic requirement for isolating nucleic acids. The process of isolating nucleic acids involves opening the cells in the sample to expose the nucleic acids, separating the nucleic acids from other cell components, and recovering the nucleic acid in purified form. Labelling of nucleic acids is a separate process that involves attaching a label or tag to the nucleic acids for specific purposes, such as tracking or detection, but it is not necessary for the basic isolation of nucleic acids.

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The statement suggests that nicks, which are breaks in the DNA strands, can occur naturally or be caused by a low concentration of the nuclease DNase I in the reaction mixture. This means that the presence of nicks in DNA can be a natural occurrence or a result of the reaction conditions, specifically the low concentration of DNase I. Therefore, the correct answer is TRUE.

The concentration of a solution of nucleic acid can be determined by measuring the absorbance at 260 nm using a spectrophotometer. Nucleic acids have a characteristic absorbance peak at 260 nm due to the presence of aromatic bases. By measuring the absorbance at this wavelength, the concentration of the nucleic acid can be determined. A spectrophotometer is the instrument used to measure the absorbance of a solution at different wavelengths, allowing for the determination of the concentration of the nucleic acid. DNA sequencers are not typically used for measuring the concentration of a nucleic acid solution.

Polynucleotide kinase is the correct answer because it is the enzyme that transfers the terminal phosphate group of ATP onto the 5'-hydroxyl termini of nucleic acid molecules. This process is known as end labelling and is commonly used in molecular biology techniques such as DNA sequencing and DNA labeling for hybridization studies.

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