What is the last step in an accident chain?

The membrane surrounding a bone is the

Congenital diseases are which of the following? genetic fatal disfiguring noninfectous

In regards to acetyl coa in the tca/kreb's cycle: how many cycles minimum would it take for an acetyl coa carbon to be removed? (what is the first step that this removal could happen? why can't we know for sure how many turns it takes?