A DNA segment has the follwing sequence 5'CCGAAT 3' What would be the sequence of the transcribed m-RNA in an erythrocyte, where does the TCA cycle occur? a. Matrix of mitochondria b. Innermembrane of mitochondria c. cell membrane d. cytosol e. None of these Destroyer says that E is the correct answer. An RBC lacks mitochondra, there is no TCA cycle. The RBC derives its energy from glycolysis: anaerobic respiration occuring in the cytosol; the ETC is contained wthin the inner membrane of the mitochondria.... I agree wtih the answer, but i dont agree with the ETC being contained within the inner mmebrane of the mitochondria...how could this be possible if RBC lacks mitochondria? #125 destroyer says norepinephrine is the primary neurotransmitter of the sympathetic nervous system.....but i thought it was epinephrine....i know both exist on symp.NS but isnt the ratio of epinephrine to norep 4:1 so wouldnt epinephrine be the primary neurtotransmitter?