introduction to cell biology.pptx by AsmatAli

asmat ali

1. An Introduction Lecture # 3 29 th Feb 2016 Cell Biology

2. Ancient Times Ancient peoples are always on the look-out for ways that organisms can be used by them. They pass on their understanding orally. Some civilizations support “great thinkers” – and philosophers, but they rarely base their thoughts on observation or experiments

3. 334 B.C - Aristotle Greek philosopher, Aristotle , begins to observe nature. He classifies all known organisms as either a Plant or and Animal. He writes that living things can arise spontaneously from non-living matter.

4. 1268 – 1 st Eyeglasses Roger Bacon, an English man makes reference to a pair of eye glasses. This means that glass is being developed and used in a way that makes it easier to see small things.

5. 1500’s Most European’s think that knowledge is unchangeable and should not be questioned. To find answers about nature, they look to the original teachings of Aristotle.

6. 1590 – 1 st Microscope Zacharias Janssen, a Dutch eyeglass maker, makes the 1 st microscope by placing two lenses on top of one another to make extra-large images.

7. 1600’s People start to question the origins of life. Many begin to suggest that life can only come from other forms of life rather than through spontaneous generation (as was suggested by Aristotle). This only took about 2000 years! William Harvey says that maggots do not come from the meat itself but from tiny eggs too small to be seen. William Harvey English Physician 1578-1657

8. 1665- 1 st cell seen Discovery of Cells English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork. He described the cells as tiny boxes or a honeycomb He thought that cells only existed in plants and fungi

9. 150-200 Year Gap??? Between the Hooke/Leuwenhoek discoveries and the mid 19 th century, very little cell advancements were made. This is probably due to the widely accepted, traditional belief in Spontaneous Generation. Examples: -Mice from dirty clothes/corn husks -Maggots from rotting meat

10. 1667 – Species Defined John Ray (1627-1705) defines a “species” as a set of individuals that can reproduce their own kind. The beginning of the end of spontaneous generation!

11. 1668 – 1 st Experiments about origins of maggots Francesco Redi (1626-1697) conducts experiments to prove that maggots do not appear in meat if flies cannot land on it!

12. Anton van Leuwenhoek 1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants

13. 1830 – Cells are studied Biology is becoming an important science and the body of knowledge is growing, especially since the improvement of microscopes. Scientists begin to study the cell extensively!

14. Development of Cell Theory 1838- German Botanist, Matthias Schleiden , concluded that all plant parts are made of cells 1839- German physiologist, Theodor Schwann, stated that all animal tissues are composed of cells

15. 1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

16. The Cell Theory Complete The 3 Basic Components of the Cell Theory were now complete: 1. All organisms are composed of one or more cells. ( Schleiden & Schwann)(1838-39) 2. The cell is the basic unit of life in all living things. ( Schleiden & Schwann)(1838-39) 3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

17. Modern Cell Theory Modern Cell Theory contains 4 statements, in addition to the original Cell Theory: The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division. All cells are basically the same in chemical composition and metabolic activities. All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc ) Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)

18. Education is the ability to listen to almost anything without losing your temper or your self confidence Robert Frost