Is there a black hole in the centre of every galaxy?

Question: Is there a black hole in the centre of every galaxy?
- Keywords:
  black hole,
  galaxy,
  space
Asked by aka Agent Jellybean to Anna, Hayley, Iain, Rebecca on 23 Jun 2015.
- Iain Bethune answered on 23 Jun 2015:
  
  Yes, scientists think that almost all galaxies have a Super-massive black hole at their centre – the black hole and the formation of the galaxy are linked somehow, but we don’t fully understand it yet.

Question: Is there a black hole in the centre of every galaxy?