Question

After cells take up one form of this molecule, it becomes accessible for antibody labeling after its target is hydrolyzed with HCl (“h-c-l”) and borax. That form of this molecule is often co-stained with Ki67 (“k-i-67”). This non-methylated molecule is the larger product of a reaction catalyzed by APOBECs, which underpins the first (-5[1])step of bisulfite sequencing. Ethynyl- and bromo·de·oxy derivatives of this molecule are used to detect cell proliferation. The letter (*) psi (10[1])denotes a form of this molecule that may help strengthen binding to the 30S subunit in one structure’s stem-loops. This molecule is generated by de·aminating cytosine, and methylating this molecule’s (-5[1])5’ (“five-prime”) carbon yields its more mutation-resistant analog that similarly forms two hydrogen bonds with adenine. For 10 points, what base replaces thymine (10[1])in RNA? ■END■ (10[2])

ANSWER: uracil [or U; or uridine; accept bromodeoxyuridine or BrdU; accept ethynyl deoxyuridine or EdU; accept pseudouridine; prompt on thymine or thymidine until “APOBECs” is read by asking “thymine/thymidine is a derivative of what other molecule?”]
<JE, Biology>
= Average correct buzz position

Back to tossups

Buzzes

PlayerTeamOpponentBuzz PositionValue
Samarth RamChicago BChicago A50-5
Andrew WangIllinois BlueIllinois Orange7010
Matthew WestleyPurdue APurdue B100-5
Jacob FinleyNotre DameSIUE12210
Liam StarnesChicago AChicago B12510
Owyn NoblePurdue BPurdue A12510

Summary