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FRET (Fo¨rster resonance energy transfer) involves the transfer of energy from an excited donor fluorophore to an acceptor molecule in a manner that is dependent on the distance between the two. A biochemistry laboratory experiment is described that teaches students how to use FRET to evaluate distance changes in biological molecules. Students measured the apparent FRET between donor and acceptor fluorophores located on the ends of several DNAs of unknown lengths, enabling them to order the DNAs according to size. In addition, students investigated site-specific DNA cleavage by restriction endonucleases, using loss of apparent FRET to determine which enzyme cut sites were present in each of the DNAs. After completing this experiment, students understood the inverse relationship between changes in FRET and changes in distance, and understood how changes in FRET could be used to monitor a conformational change in a molecule. As an extension to the experiment, a tutorial is included that uses the same DNAs to illustrate the ability of single-molecule FRET measurements to resolve heterogeneity in a sample, which cannot be done via more traditional ensemble measurements.

Collateral consequences of criminal convictions perpetuate racial hierarchy, disadvantage individuals and families, undermine communities, and harm the public by hindering reentry efforts. This Article is the first to systematically expose another overlooked characteristic of collateral consequences--the extent to which they are imposed wrongfully. Wrongful collateral consequences are those that attach erroneously and in clear violation of the law. The causes are structural. Imposing collateral consequences requires a two-step matching process. First, an administrator must match a person to his or her criminal-records data. Second, an administrator must match the criminalrecords data to the law enacting the collateral consequence--to determine whether the consequence should lawfully attach. These steps are simple to state, but difficult to implement. Errors occur at both steps. Wrongful collateral consequences arise because criminal-records data is notoriously incomplete and inaccurate. They also arise because the laws enacting collateral consequences are structurally complex--legislators employ catchall clauses to enumerate the triggering offenses and complex duration clauses to prescribe the length of the consequences. Reforms are possible. Two would get at the root causes: improving criminal-records data and simplifying collateral-consequence laws. Other reforms would leave in place the existing structure but should be implemented immediately: improvements in procedural due process, creative plea bargaining by criminal-defense counsel, and quality controls by administrators who do the two-step matching. These reforms would prevent wrongful collateral consequences at the margins, but not eradicate the problem. Wrongful collateral consequences ultimately present yet another reason why collateral consequences, and the caste system they create, are misguided and unjust. [ABSTRACT FROM AUTHOR]

FRET (Forster resonance energy transfer) involves the transfer of energy from an excited donor fluorophore to an acceptor molecule in a manner that is dependent on the distance between the two. A biochemistry laboratory experiment is described that teaches students how to use FRET to evaluate distance changes in biological molecules. Students measured the apparent FRET between donor and acceptor fluorophores located on the ends of several DNAs of unknown lengths, enabling them to order the DNAs according to size. In addition, students investigated site-specific DNA cleavage by restriction endonucleases, using loss of apparent FRET to determine which enzyme cut sites were present in each of the DNAs. After completing this experiment, students understood the inverse relationship between changes in FRET and changes in distance, and understood how changes in FRET could be used to monitor a conformational change in a molecule. As an extension to the experiment, a tutorial is included that uses the same DNAs to illustrate the ability of singlemolecule FRET measurements to resolve heterogeneity in a sample, which cannot be done via more traditional ensemble measurements. [ABSTRACT FROM AUTHOR]