How to defend AK?

[FineStyle]

I was new to the table, but I saw some wild betting and raising with mediocre hands. Too aggressive on the flop? Should I have raised the turn?

PokerStars 0.25/0.50 Hold'em (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is Button with A[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls, <font color="#666666">5 folds</font>, <font color="#CC3333">Hero raises</font>, SB calls, BB calls, UTG+1 calls.

Flop: (8 SB) 2[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, BB checks, UTG+1 checks, <font color="#CC3333">Hero bets</font>, SB calls, BB folds, <font color="#CC3333">UTG+1 raises</font>, <font color="#CC3333">Hero 3-bets</font>, SB calls, <font color="#CC3333">UTG+1 caps</font>, Hero calls, SB calls.

Turn: (10 BB) J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">UTG+1 bets</font>, Hero calls, SB calls.

River: (13 BB) 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">UTG+1 bets</font>, Hero calls, <font color="#CC3333">SB raises</font>, UTG+1 calls, Hero calls.

Final Pot: 19 BB