Conner, the former University of Pittsburgh star who overcame Hodgkin's lymphoma and a serious right knee injury to reach the NFL, broke off runs of 17 and 19 yards, leading to Bart Houston's 6-yard touchdown pass to Justin Hunter.
Bryant, who is still in the process of being fully reinstated by the league, remains suspended, but is permitted to participate in all preseason activities - including practices and games.
Tevin Coleman got the start at running back for the Falcons with Devonta Freeman previously ruled out with a concussion.
The defensive end had surgery for a torn labrum and fractured right shoulder socket in March and was held out of the preseason opener.
Steelers nose tackle Javon Hargrave left in the first quarter with a concussion, and linebacker Steven Johnson sustained a hamstring injury.
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