DNA Quantification and Standard Curve in Molecular Biology

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What is the primary purpose of determining DNA concentration?

To optimize the amounts of other reagents used in experiments (correct)
To prepare a DNA sample in a suitable solvent
To measure the absorbance of DNA at 260 nanometers
To identify potential issues such as degradation, contamination, or insufficient sample material

At what wavelength do nucleic acids exhibit characteristic absorbance patterns?

200 nanometers
260 nanometers (correct)
280 nanometers
220 nanometers

What is the purpose of performing a blank measurement in the DNA quantification protocol?

To identify potential issues in the sample
To establish a baseline absorbance value (correct)
To measure the DNA concentration
To prepare the DNA sample

What is the advantage of using a spectrophotometer for DNA quantification?

It provides a rapid, accurate, and non-destructive means of quantifying DNA (B) Signup and view all the answers

Why is it essential to ensure the DNA sample is adequately dissolved and free from contaminants?

To prevent interference with the measurement and ensure accurate results (A) Signup and view all the answers

What is the primary function of a DNA quantification protocol?

To determine the concentration of DNA (D) Signup and view all the answers

What is the purpose of wiping the outside of the cuvette or tube?

To remove any residual liquid (B) Signup and view all the answers

Why would you repeat the experiment with a different dilution?

If the absorbance reading is below 0.1 or above 1.0 (D) Signup and view all the answers

What is the wavelength at which the absorbance reading is taken?

260 nm (C) Signup and view all the answers

What is the path length of the cuvette typically used in the experiment?

1 cm (C) Signup and view all the answers

What is the unit of measurement for the average extinction coefficient (ϵ) for double-stranded DNA?

(μg/ml)−1 cm−1 (D) Signup and view all the answers

What is the formula used to calculate the concentration of DNA in the sample?

A=ϵcl/D (C) Signup and view all the answers

What is the purpose of measuring the absorbance of the DNA sample at 260 nm and 280 nm?

To assess the purity of the DNA sample (A) Signup and view all the answers

What does a ratio of absorbance at 260 nm to 280 nm of around 1.8 indicate?

Pure DNA (B) Signup and view all the answers

What is the purpose of constructing a standard curve?

To model the linear relationship between DNA concentration and absorbance (C) Signup and view all the answers

What is the equation used to estimate the purity of the DNA sample?

A260/A280 (B) Signup and view all the answers

What is the purpose of plotting the data points on the graph?

To visualize the linear relationship between DNA concentration and absorbance (A) Signup and view all the answers

What is the purpose of measuring the absorbance of the DNA sample at 260 nm and 280 nm after constructing three dilutions?

To assess the purity of the DNA sample (A) Signup and view all the answers

What is the purpose of labeling the X and Y axes in the graph?

To provide a clear and concise representation of the data (B) Signup and view all the answers

What is the outcome of the DNA quantification protocol?

A quantification of the DNA sample (C) Signup and view all the answers