Tomorrow’s Entry Card

Be ready to write the answers to these without any notes.

1. Write out the 3 ideas of the cell theory.

2. How did the microscope make the cell theory possible?

How Was the Cell Theory Developed

And what is it?

The MicroscopeAnton Leeuwenhoek was Dutch. He sold pincushions, cloth, and

such. The waiting townsfolk fumed and

fussed As Anton's dry goods gathered dust.

He worked, instead of tending store, At grinding special lenses for A microscope. Some of the things He looked at were:

mosquitoes' wings, the hairs of sheep, the legs of lice, the skin of people, dogs, and mice; ox eyes, spiders' spinning gear,fishes' scales, a little smear of his own blood,

and best of all, the unknown, busy, very smallbugs that swim and bump and hopinside a simple water drop.

Impossible! Most Dutchmen said. This Anton's crazy in the head. We ought to ship him off to Spain. He says he's seen a housefly's brain. He says the water that we drink Is full of bugs. He's mad, we think!

They called him dumkopf, which means dope. That's how we got the microscope.

Maxine Kumin

Anton von Leeuwenhoek

Dutch tradesman 1632-1723

He ran a store; microscopes were his hobby.

He discovered bacteria, blood cells and sperm.

He discovered that one drop of water could have thousands of invisible living cells.

“an unbelievably great company of livinganimalcules, a-swimming more nimbly thanany I had ever seen up to this time. Thebiggest sort. . . bent their body into curves ingoing forwards. . . Moreover, the otheranimalcules were in such enormous numbers, that all the water. . . seemed to be alive.”

Discovery of bacteria -In the mouth of old manwho had never brushed his teeth

Anton von Leeuwenhoek

Von Leeuwenhoek

•Studied pondwater, sour milk, and semen

•named moving organisms “animalcules”

•scared people and caused a sensation

Von Leeuwenhoek’s drawings of “animalcules” set off a flurry of amateur and sometimes ridiculous claims, such as:

- pondwater animalcules causing madness!

and...

Human sperm cells contain tiny human beings!

Today we can look back and think “crazy,” but at the time people took these ideas very seriously.

A Brief History of Cell Study• Robert Hooke (1635-

1708)• Invented springs and

other parts that made possible the first wrist watches

• Studied the motion of the planets

• Made a microscope and published a book Micrographia, with drawings of things he saw under his

microscope

A Brief History of Cell Study

•Robert Hooke looked at pieces of cork under his microscope.•He thought that the shapes looked like (prison) cells

The Cell Theory

•All living things contain at least one cell•Cells are the basic building blocks of all living things, and carry on all life processes.•Cells can only come from pre-existing cells

The cell theory has three parts:

The cell theory-a closer look

•All living things contain at least one cell–Many scientists working after Hooke and Leeuwenhoek observed different plants and animals–Each of them noted that no matter what they observed, if it was alive it had cells.

•Cells are the basic building blocks of all living things, and carry on all life processes.

–scientists quickly realized that when cells were dissected or broken open they died–This meant that whatever “life” is, it is something that happens inside cells

The cell theory-a closer look

•Cells can only come from pre-existing cells–does not answer the question of where the first cell came from or how it came to be.–has not been proven wrong yet- no scientist has ever built a living cell from nonliving organic molecules

The cell theory-a closer look

To summarize - Cell Theory• Cells are the basic units of structure in

all living things, and carry on all life processes.

• New cells arise only from other living cells.

• All organisms are made of one or more cells.

• THE MICROSCOPE MADE THE CELL THEORY POSSIBLE!