Cell Theory and Cell Structures Notes Assignment Fill in the blanks below. Part 1 1.Early contributions for our understanding of the cell: Robert Hooke was the first person to ______________________. Anton Leeuwenhoek saw cells in __________________ , which he called “ ____________________ “. 2.The Cell Theory a.Every living thing is made of one or more __________________. b.The cell is the basic unit of structure and _____________________. c.All cells come from _________________________________ cells.