Chapter 7Chapter 7Cell Structure Cell Structure and Functionand Function

7 -1 Life Is Cellular: The 7 -1 Life Is Cellular: The History of the Cell TheoryHistory of the Cell Theory

Anton van Leeuwenhoek: Microscope Anton van Leeuwenhoek: Microscope inventorinventor

1.1. In the early 1600s the microscope was In the early 1600s the microscope was invented.invented.

2.2. Anton van Leeuwenhoek was the first to use Anton van Leeuwenhoek was the first to use a microscope to study nature.a microscope to study nature.

3.3. van Leeuwenhoek observed tiny living van Leeuwenhoek observed tiny living organisms in pond water.organisms in pond water.

4.4. He called them “animalcules.”He called them “animalcules.”

. . . my work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me

more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all

ingenious people might be informed thereof.

Antony van Leeuwenhoek. Letter of June 12, 1716

An example of the early An example of the early type of microscope type of microscope Leeuwenhoek usedLeeuwenhoek used

The Discovery of Cells: Robert HookeThe Discovery of Cells: Robert Hooke

1.1. 1665: Robert Hooke looked at 1665: Robert Hooke looked at plant tissue (cork) under a plant tissue (cork) under a microscope.microscope.

2.2. Hooke noticed tiny chambers Hooke noticed tiny chambers which he named cells. (after the which he named cells. (after the rooms in ancient monasteries.)rooms in ancient monasteries.)

3.3. Hooke’s discovery led to other Hooke’s discovery led to other work that concluded that cells work that concluded that cells are the basic unit of all forms of are the basic unit of all forms of life.life.

Schleiden, Schwann and Schleiden, Schwann and Virchow : “All living things are Virchow : “All living things are

made of cells.”made of cells.” 1838: Matthias Schleiden, a German 1838: Matthias Schleiden, a German

botanist, concluded that all plant are made of botanist, concluded that all plant are made of cells.cells.

1839: Theodor Schwann, German scientist, 1839: Theodor Schwann, German scientist,

concluded that all animals are also made of concluded that all animals are also made of cells.cells.

1855: Rudolf Virchow, a German physician 1855: Rudolf Virchow, a German physician concluded that “where cells exist, there must concluded that “where cells exist, there must have been a preexisting cell.”have been a preexisting cell.”

The Cell TheoryThe Cell Theory(Learn this NOW!)(Learn this NOW!)

1.1. All living things are composed of cells.All living things are composed of cells.

2.2. Cells are the basic units of structure Cells are the basic units of structure and function in living things.and function in living things.

3.3. New cells are produce from existing New cells are produce from existing cells.cells.

Basic Cell StructuresBasic Cell Structures

Cells come in many shapes and sizes.Cells come in many shapes and sizes. ““normal” cells are from 5 to 50 microns in normal” cells are from 5 to 50 microns in

diameter.diameter. Some cells are huge! (Egg Cells, Nerve Some cells are huge! (Egg Cells, Nerve

cells.)cells.) Many one-celled animals can be seen Many one-celled animals can be seen

without a microscope.without a microscope.

Basic Cell Structures (Cont.)Basic Cell Structures (Cont.)

Structures common to most cellsStructures common to most cells Cell membrane – A flexible membrane that is Cell membrane – A flexible membrane that is

“selectively permeable.”“selectively permeable.” Cell wall – Provides protection and support. Cell wall – Provides protection and support.

Not found in all cells.Not found in all cells. Nucleus – Contains genetic material and Nucleus – Contains genetic material and

controls cell’s activities.controls cell’s activities. Cytoplasm – Material inside the cell excluding Cytoplasm – Material inside the cell excluding

organelles.organelles.

Prokaryotes and EukaryotesProkaryotes and Eukaryotes

Prokaryotes – (bacteria) smaller and Prokaryotes – (bacteria) smaller and simpler than other cells. Lack a simpler than other cells. Lack a membrane bound nucleus and other membrane bound nucleus and other organelles.organelles. Eukaryotes – (all plants, animals, fungi, Eukaryotes – (all plants, animals, fungi,

protists) Cells that do contain a nucleus and protists) Cells that do contain a nucleus and other membrane bound organellesother membrane bound organelles