Some single - celled eukaryotes live in places where oxygen is scarce or non-existent ; in these circumstances , mitochondria can not function , but hydrogenosomes are able to '' burn '' carbohydrates and other fuels to produce ATP without using oxygen .
Some single - celled eukaryotes live in places where oxygen is scarce or non-existent ; these eukaryotic cells use hydrogenosomes instead of mitochondria to produce ATP . 
 Without abundant oxygen mitochondria do not function , but hydrogenosomes are able to '' burn '' carbohydrates and other fuels to produce ATP without using oxygen .