This Protein Folds into a Doughnut Shape That Can Encircle

question 5

Multiple Choice

This protein folds into a doughnut shape that can encircle DNA. It can load on the DNA only when the DNA is broken in both strands, so that the DNA can thread through the hole in the protein. Which of the following proteins do you think matches this description?

• A) PCNA, the sliding clamp for DNA polymerases at the replication forks
• B) Ku, the protein that recognizes DNA ends and can initiate nonhomologous end joining
• C) MCM, the helicase critical for the initiation and elongation of replication
• D) Topoisomerase II, which can create or relax superhelical tension in DNA
• E) RecA/Rad51, which carries out strand invasion in homologous recombination

---

Definitions:

Union Dues

Fees paid by members to their respective unions, typically used to fund the activities and operations of the union, including bargaining and legal representation.

Binding Arbitration Clause

A provision in a contract that requires disputes to be resolved by arbitration, with the decision being final and enforceable by law.

Arbitrator's Decision

A binding determination made by an arbitrator, an impartial third party chosen to resolve a dispute, within the context of arbitration proceedings.

Employer

An individual or organization that hires and pays people to work for them.