Pot odds considerations if raised

[EasyTiger]

As background, I am new to both 2+2 (this is my first post) and Hold'em (started playing about 6 weeks ago). I have read a few books on Hold'em (Sklansky's Hold'em Poker, Winning low limit hold'em by Lee Jones am busy reading Sklansky's Poker Theory). I probably have about 50 playing hours - hope this sets the scene of where I am at (i.e. beginner).

My question pertains to any betting round in a Hold'em low limit game, but particularly after the flop onward (10 players). The scenario is as follows:

* Pot odds justify a bet/call the first time action comes to you
* Player to your right raises (and you couldn't reasonably have anticipated this from the player's earlier playing style)
* The action gets back to you and you need to decide whether to call or fold (based on pot odds only)

Let me use an example to clarify:

* After the flop you have a gutshot straight draw
* Odds of making the straight on the turn is roughly 11:1
* There has been some pre-flop betting and the pot offers 12:1 the first time action gets to you, so you bet/call
* When the action returns to you in the same betting round (you have been raised) and the pot now offers for argument's sake 14:1. Is the correct way to approach the decision to say that the pot needs to offer at least 22:1 to justify the call (2 x 11:1 bets) or say the first bet is gone and another bet only needs pot odds of 11:1 again, so I call? (I specifically want to ignore the potential of the pot growing after the current betting round; I think its called reverse odds)

In short, is an earlier bet made in the same betting round relevant or not when considering whether you are getting the correct pot odds for a further bet?

Hope my question is clear enough and looking forward to your comments.