General Biology Development of Microscope.pptx

History of the development of microscope

1. Cell Theory (The Development of Microscope) Lesson 2:

2. Objectives: 1. identify the contributors in the development of microscope; 2. explain the postulates of cell theory; and 3. cite the importance of acknowledging contributors in discoveries.

3. Microscope is an instrument used to see objects that are too small to be seen by the naked eye.

4. Zachrias Janssen a Dutch spectacle-maker who discovered the first compound microscope which was later disputed as many had invented their own versions of glass lenses across Europe to be used at that time. The main brass tube had a diameter of just one inch or two and carried an ebony disk at its base and a lens at each end.

5. Galileo Galilei Although he is known for telescope, he was also able to make his own microscope because of his knowledge about glass and focal lengths. It has two new lenses same as his telescope: a bi-convex objective and a biconcave eyepiece. The fame of Galileo's optical instruments inspired a search for new solutions. In the 1620s, microscopes of the Keplerian type, composed of convex lenses that furnished a reversed image were developed.

6. Kepler

7. Antony van Leeuwenhoek Instead of buying his own microscope, he made his own very odd looking version. But, with his strange looking microscope, he was able to discover bacteria and protozoa. Thus, he is now known as the “Father of Microbiology”. As strange as his microscope is, he used his dental scrapings or gunk on his teeth to look for bacteria and protozoa. He did not actually call them bacteria but instead, he called it “ animacules ”. He was able to share all these discoveries to one of his colleagues, Robert Hooke.

8. Robert Hooke

9. Robert Hooke was able to coin the term “cell” by looking at a piece of cork stripped from the trunk of the Cork Oak tree under his microscope. He got the term cell while looking at the specimen, he noticed the little chambers which reminded him of monastery cells, where monks used to sleep during that time. Unfortunately, those are dead cells and what he saw are just walls of the plant cells. In January of 1665, his observations through various lenses were published in his book Micrographia . It is particularly notable for being the first book to illustrate insects, plants etc. as seen through microscopes.

10. FORMATION OF POSTULATES OF CELL THEORY It is imperative that we talk about first the instrument used to help scientists with their study of organisms in molecular level. It is in this level that they were able to establish the postulates for this theory.

11. Despite the publication of Micrographia , it is not after almost 200 years that a breakthrough was made. Matthias Schlieden , a German botanist who loves observing his plants under the microscope, noticed that every plant is made up of cells. On the other hand, zoologist Theodor Schwann also studied different animals using his microscope and later on concluded that animals are made up of cells. He discovered a type of cell that was named after him because of his prolific study of cells.

12. It is the Schwann cells with the main function of myelinating the axons of the peripheral nervous system. Later on, Theodor wrote about his observations and sent it to his fellow scientists. With this, it is only Schlieden who responded and the two of them started working on their theories. First is that the cell is the unit of structure, physiology, and organization in living things and second is that the cells retains a dual existence as a distinct entity and building block in the construction of organisms. Everything seems to be going well until they argue on this one - where cells came from. Schlieden rejected Schwann’s idea and stated that his theory is about free cell formation – that it just kind of spontaneously crystalized into existence.

13. This is where another scientist came up with his “own” theory, Rudolf Virchow. He is known as the “Father of Modern Pathology”. He studied medicine in Berlin and then spent most of his life teaching there. Together with Benino Reinhardt, they founded Archiv für Pathologische Anatomie und Physiologie (now known as “Virchow’s Archives”) which still survives as a leading journal of pathology. He taught several persons who became famous scientists in Germany and William Welch and William Osler, 2 of the 4 famous physicians who founded Johns Hopkins Hospital. He published his now famous aphorism “ omnis cellula e cellula ” which means “every cell stems from another cell.”

14. These are the different events that lead to the formation of the Postulates of Cell Theory 1. All known living things are made up of cells. 2. The cell is a structural and functional unit of all living things. 3. All cells come from pre-existing cells by division.

15. Continued research and with advancement of technologies, additional postulates were added: 1. All cells contain hereditary information which is passed from cell to cell during division. 2. All cells are basically the same in chemical composition. 3. All energy flow of life occurs within cells.