1. What are cells?
A ______ is the basic unit of structure and function in a living thing.
Your body is composed of ______________ of cells.

2. What are cells?
You have _______cells, skin cells, muscle cells, blood cells, and many other types as well.
These are some of the types of cells found in your blood.

3. What are cells?
Each cell in your body shares the characteristics of all _______ things.

4. Finding out about cells
English scientist Robert Hooke (1635–1703) was the first to record his _______________ of cells.
In 1663, he took a thin slice of ____________and placed it under a ___________________ that he built himself.

5. Finding out about cells
As microscopes improved, scientists made many discoveries.
A modern fluorescent microscope enables scientists to use ________ __________ to see tiny cell parts such as DNA in these mouse cells.

6. The cell theory
The work of _________, __________, _______________, ____________, _________________ others led to an important theory in life science.
The __________ __________explains the relationship between cells and living things.

8. Similarities among cells
In _____-_____organisms like you, there are many different _____________ cells.
All cells share certain common _____________.

9. Similarities among cells
All cells are surrounded by a cell ________________.
All cells contain _______________.

10. Classifying cells _______________ cells do not have a nucleus.
Scientists believe that all life on Earth came from ____________ cells of this type.
Only _____________ have this type of cell.

11. Classifying cells
___________________ cells have a nucleus and membrane-covered organelles.
They tend to be about ten times _____________ than prokaryotic cells.
____________ , ____________, ____________, _____________all have eukaryotic cells.

12. Comparing cell types