History of Cells

What is a Cell?

Cell• A cell has all the items necessary to carry out life’s

activities.• Every living thing has at least one cell.• Need a microscope b/c smaller than a period at the

end of a sentence. Ex. Chicken egg

What does a cell look alike?

Human red and white blood cells

Human embryo

Mitosis – Cell Division

White cells moving to attack

A human nerve cell

Human liver cells

Cancer cells in a human liver

Volvox – a protist

Euglena – plant-like protist Amoeba

Paramecium – a protist

Animal-like protist

The largest cell – what is it?

So, who are the important people in

history and discovery of cells

Hans and Zacharias Janssen •Dutch lens grinders, father and son

•produced first compound microscope (2 lenses)

Robert Hooke• Discovered cells in 1665• English scientist • Wasn’t even looking for cells! He was trying to impress other

scientists.• Made a slide of Cork tree & looked at it with a simple microscope.• looked at a thin slice of cork (oak cork) through a compound

microscope • observed tiny, hollow, roomlike structures • called these structures 'cells' because they reminded him of the rooms that monks lived in • only saw the outer walls (cell walls) because cork cells are not alive

The 1st Cell• Looked like 100’s of little boxes or honeycomb• Hooke named them cells, which means “little rooms” in Latin.• Hooke thoughtcells were only inplants & fungi b/c

they have cell walls.

Anton van Leeuwenhoek• Dutch fabric merchant and amateur scientist • 1673• looked at blood, rainwater, scrapings from teeth through a

simple microscope (1 lens) • observed living cells; called some 'animalcules' which means

“little animals.”• some of the small 'animalcules' are now called bacteria

Fish, birds, & frogs have oval shaped blood cells.

Humans & dogs have flatter blood cells.

Matthias Schleiden• German botanist • 1838, 2 centuries later, realized that all living things

had cells by looking at plants. • viewed plant parts under a microscope • discovered that plant parts are made of cells

“Hmmm…do all the parts of a plant have cells?”

Theodor Schwann

• 1839• German• Found that all animals have cells• Co-wrote the Cell Theory w/ Rudolf Virchow.

“Animals are full of cells!”

Rudolph Virchow •(1855)

•German doctor, anthropologist, public health activist, pathologist, pre-historian, biologist and politician.

•stated that all living cells come only from other living cells

•He is referred to as the "Father of Pathology".

Other important dates:

1830 – Joseph Jackson Lister – invent prototype for the compound microscope

1932 – Frits Zernike invented the phase-contrast microscope. The phase-contrast microscope that allowed for the study of colorless and transparent biological materials

1931 – Ernst Ruska and Max Knoll invented the electron microscope. Electron microscope make it possible to view objects as small as the diameter of an atom. 1981 – Gerd Binnig and Heinrich Rohrer invented the scanning tunneling microscope. The scanning tunneling microscope that gives three-dimensional images of objects down to the atomic level.

Lynn Margulis• Theory-believes that one-

celled organisms gave rise to the cells we have today.

• Her theory is that 1.2 billion years old larger cells began eating smaller cells

Ex. White blood cells and other cells

• But, some small cells resisted and changed the larger cell.

Robert Brown •Around 1833 reported the discovery of the nucleus. •Brown was a naturalist who visited the "colonies of Australia" from 1801 through 1805, where he cataloged and described over 1,700 new species of plants.

The Cell TheoryThe modern tenets of the Cell Theory include: 1. all known living things are made up of cells. 2. the cell is structural & functional unit of all living things. 3. all cells come from pre-existing cells by division. (Spontaneous Generation does not occur). 4. cells contains hereditary information which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition. 6. all energy flow (metabolism & biochemistry) of life occurs within cells.

2 Types of Cells

ProkaryoticCells

• No nucleus• No membrane covering the organelles• Circular DNA• Bacteria

Eukaryotic Cells

• Nucleus• Membrane covering the organelles• Linear DNA• Are all other cells

Hereditary Material

• DNA- deoxyribonucleic acid• Controls all the cells activities • Contains the info. for making new cells.