I need a short jQuery code to do the following.

I got a dropdown like this:

```
<select id="pa_size">
    <option value="32cm">32 cm</option>
    <option value="52cm">52 cm</option>
</select>

```

And some other checkboxes under that dropdown. 

**Now my problem is:** 
I want to disable the checkboxes IF the 52 cm option is selected. 
By default the checkboxes are enabled, and if returned to 32cm from 52cm it should be working again.