2.1 Cell Theory and Microscopes
Notes
The cell is the basic unit of life. Microscopes made it possible to see cells.
- Robert Hooke named "cells" after looking at cork (1665). Leeuwenhoek first saw living single-celled organisms.
- Cell theory: (1) all living things are made of cells, (2) the cell is the basic unit of structure and function, (3) all cells come from pre-existing cells.
- Light microscopes can view living cells; electron microscopes show much finer detail but usually need dead, prepared samples.
- Cells stay small because a small cell has a large surface area to volume ratio, so materials move in and out fast enough.
Practice
Which statement is part of cell theory?
Cell theory says new cells come only from division of existing cells.
As a cell grows larger, what happens to its surface area to volume ratio?
Volume grows faster than surface area, so the ratio drops and the cell has trouble exchanging materials.
A student wants to watch a living paramecium swim. Which tool should she use?
Light microscopes can view living specimens.
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