Cell Theory PDF

CELL THEORY Objectives 1. To Explain and understand the postulates of the cell theory. 2. To know the value and the essence of understanding and learning about the cell theory and its application to human life specifically during this time of Pandemic.  State the name of the followin...

CELL THEORY Objectives 1. To Explain and understand the postulates of the cell theory. 2. To know the value and the essence of understanding and learning about the cell theory and its application to human life specifically during this time of Pandemic.  State the name of the following Scientists and give their contribution in the development of the cell theory. Anton Van Leeuwenhoek Rudolf Virchow Matthias Schleiden Theodore Schwann Robert Hooke  https://www.youtube.com/watch?v=4 OpBylwH9DU&t=301s  The Cell Theory Some Random Cell Facts The average human being is composed of around 100 Trillion individual cells!!! It would take as many as 50 cells to cover the area of a dot on the letter “i”  1590- A Dutch spectacle-maker Zacharias Janssen invented a primitive microscope with the help of his father, Hans. This microscope would later be used by Marcello Malphigi and Robert Hooke. 1665- 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 1665-1676-Italian Scientist Marcello Malphigi and English Botanist Nehemiah Grew conducted separated investigations on plants cells.The determined the presence of the organelles within its cells.  1673- A Dutch Biologist who 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 Anton van animals as well as plants Leuwenhoek  150-200 Year Gap??? Between the Hooke/Leuwenhoek discoveries and the mid 19th 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  1831- Previous discoveries mostly dealt with cells in general Then , Scottish botanist Robert Brown made a series of discoveries about cell organelles and ultimately discovered the nucleus. This became a major breakthrough in the history of Biology. 19 th Century Advancement Much doubt existed around Spontaneous Generation Conclusively disproved by Louis Pasteur + Development of Cell Theory 1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells  1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.  Development of Cell Theory Based on the data of the previous studies and his own observations on cells, 1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, declared “ Omnis Cellula e cellula” which meant that cells must arise from preexisting cells.” With this conclusion the cell theory was completed. The Cell Theory Complete The 3 Basic Components of the Cell Theory were now complete: 1. All Living 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) 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) Microscopy: Foundation of Cell Theory Compound Light Microscope ✔ Light passes through a specimen & 2 lenses to form an image. ✔ Produces magnifications about 100 - 1,000 X. ✔ Specimens may be live or dead. Transmission Electron Microscope 1931- developed by Ernst Ruska and Max Knoll Focus beams of electrons on specimens 1000x smaller than can be viewed with Light microscope it relied on electrons and not on light. Scanning Electron Microscope 1942- Ruska designed the first Scanning electron microscope SEM which transmitted a beam of electron across the specimen’s surface. Produces incredible 3-D images of entire specimen. Parts of a Compound Microscope