MICROSCOPES. Write down the stuff in GREEN (minimum)

Transcription

1 MICROSCOPES Write down the stuff in GREEN (minimum)

2 Look at your hand One square centimeter of skin contains more than 100,000 cells. No matter how closely you look with your eyes, you won t be able to see individual skin cells. How the heck did we figure out they were there?

3 With microscopes! Microscope technology had to be invented before we could know that cells existed.

4 100 A.D. Romans began blowing glass to make shapes. They made glass by super-heating sand. *

5 The Romans began experimenting with this blown glass and discovered that if you looked through curved glass, it made things look bigger.

6 Someone also discovered that you can focus the rays of the sun with one of these special glasses and start a fire. These early lenses were called magnifiers or burning glasses. A simple microscope like this one has only one lens.

7 Fun fact: The word lens is derived from the Latin word lentil, as they were named because they resembled the shape of a lentil bean.

8 Around 1280 spectacle makers were producing lenses to be worn as glasses.

9 The early simple microscopes were really only magnifying glasses and had a magnification power of 6x to 10x. One thing that was very common and interesting to look at was fleas and other tiny insects. These early magnifiers were therefore called flea glasses.

10 Around 1590, a Dutch spectacle maker named Zacharias Jansen put several lenses in a tube, created the first compound microscope, and discovered that he could see VERY tiny things. Two or more lenses put together make a compound microscope.

11 Galileo, in Italy, heard about Jansen s new magnifier and began making refinements to his telescopes using the same ideas. This spyglass was used on Italian ships.

12 About 1660, an Englishman named Robert Hooke made a compound microscope that had a lamp for lighting specimens. The light was focused onto the specimen and it could be seen in greater detail not just the outline. He called the little rooms he saw CELLS.

13 A light microscope uses light to see a specimen

14 In about 1674, a Dutch fabric merchant named Antonie van Leeuwenhoek began fiddling with ways to see the threads of his fabrics better.

15 He began looking at pond water and discovered that it was ALIVE! He gave these tiny creatures the nickname animalcules (write next to 1674)

16 Antonie also began finding interesting stuff everywhere even in the gunk on his own teeth! He eventually made microscopes that could magnify 266 times. He also was the first to see bacteria. (Not bad for a non-scientist type!)

17 Leeuwenhoek sent drawings like this to the Royal Society of London

18 In about 1860, a German named Carl Zeiss began making REALLY good compound light microscopes, and we saw individual cells for the first time. He perfected his lenses by using mathematical calculations.

19 Even now, most good microscopes are made in Germany or Japan. The cheap ones that you can buy as part of a science kit have plastic lenses that aren t that great.

20 In 1933, a German named Ernst Ruska created the first electron microscope. Transmission Electron Microscopes (TEM) send electrons through very thinly sliced specimens. They can magnify up to 500,000 times. Organelles inside of a cell.

21 In 1965, Scanning Electron Microscopes were invented. These send electrons over the surface of a specimen and create images that are almost like 3-D.

22 In 1981, the Scanning Tunneling Microscope was invented. These measure electrons that leak from the surface of a specimen. These are the type used to look inside cells and cell organelles. Silicon molecule through STM

23 Next: Find out how to use a microscope