A Scientist Is Using Crosslinked Chromatin Immunoprecipitation (XChIP) to Determine

question 23

Multiple Choice

A scientist is using crosslinked chromatin immunoprecipitation (XChIP) to determine the DNA sequences to which a protein of interest binds. However, when she attempts to sequence the DNA in the last step of the procedure, she is unable to obtain any DNA to sequence. Which of the following is a likely reason she is getting these results?

• A) The antibody she is using to precipitate the protein-DNA complex is not specific enough and binds the protein in question and five other proteins.
• B) The protein and DNA are not properly crosslinked.
• C) The antibody she is using is not specific to the DNA sequence to which the protein binds.
• D) The DNA is too tightly complexed with histone proteins to allow sequencing.
• E) The cells were lysed during the precipitation stage of the process.

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Definitions:

Confidence Interval

A collection of numbers, sourced from sample data, presumed to contain the value of an undiscovered population characteristic.

Population Variance

The variance of a population data set, calculating the mean of the squared deviations from the mean of the data.

Confidence Interval

A range of values, derived from the sample data, that is likely to contain the value of an unknown population parameter.

Sample Variance

A measure of variability that quantifies the spread of a sample data set; calculated as the sum of squared deviations from the sample mean, divided by the sample size minus one.