well, you can do that..however, i strongly suggest you DI it first. The important thing in capturing a "full" sound is impedance matching. i don't know whether you understand how impedence works, and if you don't it doesn't really bare much concequence, but it's still important to "obey" the impedence rules.
A bass's output has a high impedance, and the line input on your mixer will probably have a lower impedance, which means the bass could lose some of its "fullness" and "life". A line-level output from an amp would be ok, or from a DI box.
the whole impedance thing is a bit complexe, but if you think of the analogy of water in a pipe its a bit simpler: the bass's output has a small pipe full of water, whereas the input of your mixer as a very fat pipe. the same amount of water is still there, its just not as full.
For impedence matching, remember the following:
"High-to-low won't go"
"Low-to-high will fly"
and also try out, for the fun of it, plugging your bass straight into your mixer. who knows what it could be like! see if you can hear the quality loss due to bad impedence matching..
hope this helps and makes sense!
try reading
this thread for some more help, or using the search function, there's quite a lot of posts about this..
MD