Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Cytokinesis wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell growth wikipedia , lookup
Tissue engineering wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cell culture wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
What are Cells? Cells are the basic unit of life. History of Cells & Cell Theory Who Was Involved? The cell theory grew from the work and research of many scientists. First to View Cells • In 1665, Robert Hooke was the first to use a light microscope to examine a thin slice of cork (dead plant tissue) • What he saw looked like small boxes Hooke's Microscope Hooke's drawing of Cork Cells First to View Cells • Hooke is responsible for naming cells. • Hooke called them “CELLS” because they looked like the small rooms that monks lived in (called cells). Anton van Leeuwenhoek (LAY-vuhn-hook) • Dutch microscope maker. • One of the first people to use a microscope to study living things in nature & was the first to view microorganisms . • Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth. • Observed living cells, which he called “animalcules.” Beginning of the Cell Theory • In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells • Schleiden is a cofounder of the cell theory Beginning of the Cell Theory • In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells. • Schwann also cofounded the cell theory. Beginning of the Cell Theory • In 1855, a German medical doctor named Rudolph Virchow observed, under the microscope, cells dividing. • He reasoned that all cells come from other preexisting cells by cell division. Three Principles of Cell Theory Cell Theory 1. All living things are made of one or more cells. 2. Cells are the basic unit of structure and function in an organism (they are the smallest unit that can perform life functions). 3. Cells come from the reproduction of existing cells (cell division). Why is the Cell Theory called a Theory and not a Fact? Principle #1 All organisms are made of one or more cells. • Some organisms are made up of one cell or unicellular • Others are multicellular or made up of many cells Principle #2 The cell is the most basic unit of life. Principle #3 All existing cells are produced by other living cells. Characteristics of Cells 1. They are flexible in function • • Become different types of tissues and material Ex: fetal development 2. They can let things in and out • • Communication Getting nutrients, energy 3. They have their own command center • DNA tells cells what to do 4. They have the ability to divide and make more • Ex: growth & reproduction Cell Size Cells are small so they can exchange materials with their surroundings. Surface area relative to the volume decreases as size of cell increases. - limits the size of cells Cells need a large surface area to absorb enough nutrients. Factors Affecting Cell Size Surface area = 24 • Volume of a cell is Volume = 8 determined by multiplying length times width times 2 height (L x W x H). • Surface area (cell 2 membrane) is the total 2 area (L x W) of all sides (the entire surface of the object). 4 • Therefore, Volume increases FASTER than the surface area. Surface area = 96 (only 4 times greater) Volume = 64 (8 times greater) 4 4 Cell Size • When the surface area is no longer great enough to get rid of all the wastes and to get in enough food and water, then the cell must divide. • Therefore, all of the cells in an organism are close in size. Cell Size Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse? Cell Size Answer: The elephant’s cells are about the same size as those of the mouse, but the elephant has MANY MORE cells than the mouse. Sizes of living things