Afalava, a 2009 sixth-round draft choice, started 13 games for the Bears last season, recording 70 tackles and one forced fumble.
Bullocks, sidelined much of the preseason by injury, graded out highly in the Bears final few games of the 2009 regular season.
The Bears must cut their roster to the NFL-mandated 53 players by 5 p.m. CT Saturday.
Jeff Dickerson covers the Bears for ESPNChicago.com and ESPN 1000. Michael C. Wright contributed information to this story.