14. What is the endoplasmic reticulum and how is it associated with ribosomes? What chemical processes of the cell take place at the endoplasmic reticulum?

15. In what sense is the ribosome-free side of the endoplasmic reticulurn "outside" the cell? In what sense is a mitochon drion "outside" the cell even though it is physically surrounded by it?

16. What is a Golgi complex? What is its biochemical function?

17. How many membranes does a mitochondrion have? How many mitochondria are found in a typical eucaryotic cell?

18. What energy-related biochemical reactions take place within a mitochondrion?

19. Some of the enzymes for the reactions of Question 18 float freely in the mitochondrial matrix, whereas others are embedded in the inner membrane surface. Which enzymes are found where?

20. In what ways do mitochondria resemble bacteria? How could such a resemblance have come about?