Question

"Nucleic acid was isolated by lysing cells in detergent, guanidine isothiocyanate, and DNAse, followed by extraction in an acid phenol chloroform isoamyl alcohol solution and finally precipitation in ethanol. The concentration of the isolated nucleic acid was measured using SyBr Green II, which yielded fluorescence. When PicoGreen was used to quantitate the nucleic acid, there was no fluorescence in the sample. What type of nucleic acid was isolated?

Answer 1

RNA

Step-by-step explanation:

The nucleic isolated was quantified by 2 types of fluorescent dyes, which binds only to specific type of nucleic acid. You can find the information on the specificity of dyes on your labsheet or dye supplier's website. For our dyes, however:

• SyBr Green II only emits fluorescent light when it binds to RNA or Single Strand DNA
• PicoGreen only fluoresce when bound to Double Strand DNA

With these information, we know that our nucleic acid is either single strand DNA or RNA, however, it is also mentioned that

"Nucleic acid was isolated by lysing cells in detergent, guanidine isothiocyanate, and DNAse"

DNAse, which is an enzyme that breaks down DNA, destroys any extracted DNA during the process, thus, the only possible nucleic acid we have isolated is RNA