AKo Dilema (a repeating problem for me)

[Dunkman]

I've been lurking around the forums and decided maybe if I started posting instead of watching I may actually get bettter, so here goes. I seem to lose a lot of money playing top pair...I think this is one of my largest problems right now. Looking back I should have bet $2 on the flop, but even so I still have no idea what to do on the turn if I get called. Only have 21 hands on CO, is 52/24/2.6, I've seen them call a raise or raise twice preflop with ace-rag. Thanks for the help!

PokerStars No-Limit Hold'em, $0.10 BB (9 handed) converter

MP2 ($9.45)
MP3 ($3.20)
CO ($19.45)
Button ($12.90)
SB ($9.30)
BB ($9.85)
Hero ($16.85)
UTG+1 ($3.55)
MP1 ($6.90)

Preflop: Hero is UTG with A[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/heart.gif[/img].
<font color="#CC3333">Hero raises to $0.5</font>, <font color="#666666">4 folds</font>, CO calls $0.50, <font color="#666666">1 fold</font>, SB calls $0.45, <font color="#666666">1 fold</font>.

Flop: ($1.60) A[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets $1.2</font>, CO calls $1.20, SB folds.

Turn: ($4) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>

Hero? <font color="red"> </font>