HA15 is a high magnification EM of a region of cytoplasm that contains both RER and SER. Mitochondria (M) and a portion of the nucleus (N) can also be seen. Note that in at least one place you can see that the RER and SER are continuous with each other (arrow HA15L). To apply what you have learned so far, answer these two questions. Where are proteins that are resident in the SER made? Where are lipids that are components of RER membranes made?