Cheryl is performing sds-page gel electrophoresis but she forgets to heat her samples with sds. which of the following occurs as a result of cheryl’s mistake?
a. proteins separate by charge instead of by molecular mass b. polypeptides do not unfold and thus migrate at slower rates through the gel c. proteins do not migrate through the gel d. all of the above may occur as a result of cheryl’s mistake

 B. Polypeptides do not unfold and thus migrate at slower rates through the gel.

Explanation:

SDS-PAGE is a gel electrophoresis used to separate charged molecules by their molecular masses in an electric field. To do this, it uses SDS (sodium dodecyl sulfat) to isolate proteins.  

SDS is an amphipathic surfactant which covers the intrinsic charge of the proteins. It denatures proteins by binding to the chain and coating the protein with surfactant molecules.  So it disrupts the tertiary structure of proteins, and this brings the folded proteins down to linear molecules which makes them have similar charge-to-mass ratios.

Proteins treated with SDS will have a negative charge, and during the application of a constant electric field, the protein migrate towards the anode (positive charge), each with a different speed according to the mass.

Without SDS, proteins do not unfold and wont be uniformly negatively charged. This means migrate slower.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).