system
Given the following post, respond as if you're commenting on Reddit:
human
Is the form of a galaxy influenced by the black hole in its middle?
gpt
There are many things that determine the morphology of a galaxy, one of them being the black hole at its core. There is a well known relationship between the mass of the black hole and the mass of a galactic bulge- namely a spherical conglomeration of stars in the middle of the Galaxy. Black hole mass is correlated with other aspects of the Galaxy too besides the bulge mass, namely the luminosity (and velocity dispersion but never mind). 

Furthermore the black hole can also feed off nearby gas and grow. In the process of ingesting ambient material, the black hole can cause massive outflows of super hot relativistic gas - like a fountain - basically spraying plasma into the universe. This gas can heat the environment well beyond the Galaxy disc to millions of degrees inhibiting the future condensation of gas into stars. The effect of black hole heating can be to suppress the formation of new stars meaning that the Galaxy will appear older and redder lacking young newly formed young blue stars. Although this process (known as "feedback") can be short in duration, the effect can be dramatic and cause what's know as an active galactic nucleus or even quasars.