PokerStars No-Limit Hold'em, $0.50 BB (4 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG ($114.80)
Hero ($50)
SB ($48.75)
BB ($52.45)

Preflop: Hero is Button with J, J.
UTG calls $0.50, Hero raises to $2.5, 2 folds, UTG calls $2.

Flop: ($5.75) 3, 5, 2 (2 players)
UTG checks, Hero bets $4.5, UTG calls $4.50.

Turn: ($14.75) 5 (2 players)
UTG checks, Hero ???

---

Villian is an unknown.

Do you bet this turn, and why?