1. Chapter 7 Cell Structure and Function

2. The Discovery of the Cell
7-1 Life is Cellular
The Discovery of the Cell
Because there were no instruments to make cells visible, the existence of cells was unknown for most of human history.
This changed with the invention of the microscope.

3. Early Microscopes
In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material.
Cork looked like thousands of tiny, empty chambers.
Hooke called these chambers “cells” after tiny rooms called cells.
Cells are the basic units of life and contain living matter.

4. Hooke’s Drawing of Cork Cells

5. Around the same time, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things.
The microscope revealed a world of tiny living organisms.

6. The Cell Theory
In 1838, Matthias Schleiden concluded that all plants were made of cells.
In 1839, Theodor Schwann stated that all animals were made of cells.
In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells.
These discoveries led to the cell theory.

7. 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.

9. Exploring the Cell
New technologies allow researchers to study the structure and movement of living cells in great detail.

10. Prokaryotes and Eukaryotes
Cells come in a variety of shapes and sizes.
All cells have 2 characteristics in common
They are surrounded by a barrier called a cell membrane.
At some point they contain the molecule that carries biological information- DNA.

11. Cells are classified into 2 categories, depending on whether they contain a nucleus.
The nucleus is a large membrane-enclosed structure that contains the cell's genetic material in the form of DNA.
The nucleus controls many of the cell's activities
(nucleus = the brain of the cell)
*Eukaryotes are cells that contain nuclei.
*Prokaryotes are cells that do not contain nuclei.
(nuclei is plural form of nucleus)

12. What are the characteristics of prokaryotes and eukaryotes?

13. Prokaryotes
Prokaryotic cells have genetic material that is not contained in a nucleus.
Prokaryotes do not have membrane-bound organelles.
Prokaryotic cells are generally smaller and simpler than eukaryotic cells.
Bacteria are examples of prokaryotes.

14. Eukaryotes
Eukaryotic cells contain a nucleus in which their genetic material is separate from the rest of the cell.
Eukaryotic cells are generally larger and more complex than prokaryotic cells.
Eukaryotic cells generally contain dozens of structures and internal membranes.
Many eukaryotic cells are highly specialized.
Plants, animals, fungi, and protists are all examples of eukaryotes.

15. 7-4 The Diversity of Cellular Life

16. The _______________________among living things arise from the ways in which cells are specialized to perform certain tasks and the ways in which cells associate with one another to form ______________________organisms.

17. Unicellular Organisms
Unicellular organisms are made up of only one cell. (prefix uni- means one)
Unicellular organisms dominate life on Earth.
Unicellular organisms include some fungi and protozoans, fungi, and bacteria.
They do grow, respond to their environment, transform energy, and reproduce.

18. Amoeba
Bacteria (bacillus)
Fungi
Bacteria (cocci)
Paramecium

19. Multicellular Organisms
Organisms that are made up of many cells are called multicellular. (prefix multi- means many)
There is a great variety among multicellular organisms
Multicellular organisms depend on communication of specialized cells.

21. Cells throughout an organism can develop in different ways to perform different tasks.
This process is called cell specialization.

22. Specialized Animal Cells
Animal cells are specialized in many ways.
Red blood cells transport oxygen.

23. Cells in the pancreas produce proteins.

24. Muscle cells allow movement.

25. Specialized Plant Cells
Plants exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves.
Highly specialized cells, known as guard cells, regulate this exchange.

26. Stomata enclosed by guard cells.

27. Levels of Organization
The levels of organization in a multicellular organism from smallest to largest are:
individual cells
tissues
organs
organ systems

28. In multicellular organisms, cells are the first level of organization.

29. Tissues
Similar cells are grouped into units called tissues.
A tissue is a group of similar cells that perform a particular function.

30. Most animals have four main types of tissue:
muscle
epithelial
nervous
connective

31. Organs 
Organs are groups of tissues that work together to perform a specific function.

32. Organ Systems
In most cases, an organ completes a series of important tasks.
A group of organs that work together to perform a specific function is called an organ system.