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Ch 7: Cell Structure and Function
7-1 Life is Cellular
A. The Discovery of the Cell
1. Because there were no instruments to make cells visible, the existence of cells
was unknown for most of human history.
2. This changed with the invention of the microscope.
3. ____________ - in 1665, used an early
Draw what Hooke saw when he
compound microscope to look at a thin slice of
looked at cork cells
cork, a plant material.
a. Cork looked like thousands of tiny, empty
chambers.
b. Hooke called these chambers “cells”
c. Cells- the basic units of life.
4. Anton van Leeuwenhoek- used a single-lens
microscope to observe pond water and other things.
5. The microscope revealed a world of tiny living organisms.
6. ___________- in 1838, concluded that all plants were made of cells.
7. Theodor Schwann- in 1839, stated that all animals were made of cells.
8. Rudolph Virchow- in 1855, concluded that new cells were created only from
division of existing cells.
9. These discoveries led to the cell theory.
The cell theory states:
•All living things are composed of cells.
•Cells are the basic units of structure and function in living things.
•New cells are produced from existing cells.
B. Exploring the Cell
1. New technologies allow researchers to study the structure and movement of living
cells in great detail.
2. Electron Microscopes- reveal details 1000 times smaller than those visible in light
microscopes.
a. can be used to visualize only nonliving, preserved cells and tissues.
3. Transmission electron microscopes (TEMs)
a. Used to study cell structures and large protein molecules
b. Specimens must be cut into ultra-thin slices
4. Scanning electron microscopes (SEMs)
a. Produce three-dimensional images of cells
b. Specimens do not have to be cut into thin slices
5. Confocal Light Microscopes- scan cells with a laser beam.
a. This makes it possible to build three-dimensional images of cells and their
parts.
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6. Scanning Probe Microscopes- allow us to observe single atoms.
a. Images are produced by tracing surfaces of samples with a fine probe.
C. Prokaryotes and Eukaryotes
1. Cells come in a variety of shapes and sizes.
2. All cells:
a. are surrounded by a barrier called a cell membrane.
b. at some point contain DNA.
3. Cells are classified into two categories, depending on whether they contain a
nucleus.
4. ____________- a large membrane-enclosed structure that contains the cell's
genetic material in the form of DNA.
5. The nucleus controls many of the cell's activities.
6. ____________- cells that do not contain nuclei.
a. Smaller and more simple
b. Ex: bacteria and ostrich egg
7. Eukaryotes- cells that contain nuclei.
a. contain a nucleus in which their genetic material is separated from the rest
of the cell.
b. generally larger and more complex than prokaryotic cells.
c. generally contain dozens of structures and internal membranes.
d. Many are highly specialized.
e. Ex: plants, animals, fungi, and protists
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*Label the prokaryotic cell and the eukaryotic cell.
*Label the cell membrane, cytoplasm (used twice), nucleus, organelles
~ What type of cells make up your body?
prokaryotic
~ What type of cell is a bacteria cell?
A: prokaryote
Highlight or circle the correct answer.
Cell membrane
Nucleus
Cell size
Complexity
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or absent
present or
or large
or complex
or absent
or absent
small
or
simple or