This is the beginning of the Jimmy Garoppolo Era for the 49ers.

On Tuesday, head coach Kyle Shanahan told his quarterbacks that Garoppolo will start this Sunday when the 49ers play the Chicago Bears.

Garoppolo, 26, will replace former starting quarterback C.J. Beathard, who suffered a left knee contusion and hip strain Sunday against the Seattle Seahawks. Beathard may not be healthy enough to play this week. Shanahan will give an update on Beathard’s status today.

Garoppolo made his debut with the 49ers last Sunday after Beathard got injured. Garoppolo entered the game with 1:07 left in the fourth quarter and threw a touchdown pass to wide receiver Louis Murphy as time expired.

The 49ers traded for Garoppolo on Oct. 30 — the day before the NFL’s trade deadline. In the deal, the 49ers sent their second-round draft pick in 2018 to the New England Patriots.

For the next four weeks, the 49ers kept Garoppolo on the bench. Shanahan said the former Patriots QB didn’t know the 49ers’ system well enough.

“Is Jimmy going to be the best he can? To me, that’s impossible,” Shanahan said last Wednesday. “He just hasn’t been here long enough. I don’t think we’re going to see Jimmy’s best football, to be fair to him, until next year.”

Garoppolo is scheduled to be a free agent after this season. The 49ers can retain his rights with the franchise tag, which they plan to give him, according to Shanahan. The tag is a one-year contract that would pay him more than $24 million next year.

Garoppolo is a former second-round draft pick who spent his first three seasons in the NFL backing up Tom Brady. Since entering the league, Garoppolo has started two games, attempted 96 passes and thrown for 708 yards, six touchdowns and zero interceptions. His completion percentage is 67.7 and his quarterback rating is 110.1.