Microscopes and the Cell Theory

All About Cells

At lot of times, when we think of a object, we think of it as it is today.For example, a cell phone.

So when we think of cell phones, we think of the ones we see today.

The ones that we know and many of us use.

But what about the original cell phones?

Just as there are difference between the cell phones we use now and the original cell phones, there are also differences in the microscopes we use today and what the original scientists who first looked at cells had available to them.

Historical microscope images, and more, can be found at: http://www.techinst.com/

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The observations and conclusion of many scientists helped to develop the current understanding of the cell.Robert HookeAnton van LeeuwenhoekMatthias SchleidenTheodor SchwannRudolph Virchow

Early ScientistsRobert Hooke

(1665)Observed a cork

slick and saw that it seemed to be made up of tiny, empty chambers.

Hooke called these chambers cells, because they resembled the tiny rooms of a monastery.

Early ScientistsAnton van

Leeuwenhoek (1674)Used a single-lense

microscope to observe pond water

Saw tiny living organisms, which he called “animalcules” and we know today as bacteria

Matthias Schleiden (1838) – concluded that all plants are made up of cells

Theodor Schwann (1839) – concluded that all animals are made up of cells

Rudolph Virchow (1855) – proposes that all cells come from preexisting cells, completing the cell theory

Cells are the basic unit of life.

The cell theory states that:

All living things are composed of cells

Cells are basic units of structure and function in living things

New cells are produced from existing cells

Remember, before the Cell Theory, we had Spontaneous Generation – that life can arise from nonliving matter.

The scientists who worked to disprove this idea are: RediSpallanzaniPasteur

Common Microscope Types:

Light microscope – living organisms, but low resolution

Electron microscopes - view details 1000 times smaller than visible in light microscopes. Non-living specimens. Requires vacuum.

Scanning Probe microscopes – Can operate in air, and can show DNA, protein molecules, and even single atoms.

Light Microscope

Electron Microscopes Transmission Electron microscopes –

requires thin specimens, can view cell structures and large protein molecules.

Electron microscopes Scanning Electron microscopes – 3D

Scanning Probe Microscopes

PROKARYOTES EUKARYOTESDNA Cells that have

genetic material that is not contained in a nucleus; called a nucleoid region

Cells that contain a nucleus in which their genetic material is separated from the rest of the cell

Size 0.2-10μm 5-100μmOrganization

Usually single-celled; generally smaller than Eukaryotes

Can be single celled, but often multicellular

Examples Bacteria Plants, animals, protists, fungi