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10/24/2013 If all living things are made from cells, then what does that include? Cell Biology Volvox globator What is a cell? Escherichia coli A chicken egg and an ostrich egg Eubacteria Archaebacteria Protists Fungi Plants Animals Brief History of The Cell Theory It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The cell is the basic structural and functional unit of all known living organisms. Some organisms are unicellular (made of only one cell) while others are multicellular (made up of several cells). The Cell Theory Cells are the basic units of life All living things are made up of cells. The cell was first discovered by Robert Hooke in 1665. He examined very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments of a honeycomb. Because of this, Hooke called them cells, the name they still bear. However, he did not know their real structure or function. Diagram of a louse from Hooke's book, Micrographia Brief History of The Cell Theory The first man to witness a live cell under a microscope was Antonie Phillips van Leeuwenhoek, who in 1674 described the algae Spirogyra and named the moving organisms animalcules, meaning "little animals". Leeuwenhoek probably also saw bacteria. Antonie van Leeuwenhoek New cells are made from existing cells. This theory applies to anything living! A drawing of a tree section made by Van Leeuwenhoek. 1 10/24/2013 In 1839, Theodor Schwann and Matthias Jakob Schleiden suggested that cells were the basic unit of life. In 1858, Rudolf Ludwig Virchow concluded that all cells come from pre-existing cells, thus completing the classical cell theory. M. Schleiden T. Schwann Antoine Phillips van Leeuwenhoek’s microscope Evolution of Microscope Brief History of The Cell Theory Robert Hooke’s microscope Optical microscope Electron microscope Digital microscope R. Virchow Who Discovered the Cell Theory? 1665 – Robert Hooke What the Cell?! size & _____ shape of a cell relate to its function. The ____ • Looked at cork & named cells 1674 – Anton van Leeuwenhoek • Looked at living cells & improved microscope I am a heart cell! I am a skin cell! 1838 – Matthias Schleiden I am a prison cell! • Looked at plants & determined that plants were made of cells 1839 – Theodor Schwann • Looked at animals & determined that animals were made of cells 1855 – Rudolph Virchow • Stated that all cells come from other living cells How Did They See the Cell? They used microscopes! Micro means ________. SMALL A microscope is a tool we use to see small objects. Cell Specialization – Division of Labor PRACTICE QUESTION An advantage that multicellular organisms have over unicellular organisms is that – a. unicellular organisms can grow larger than multicellular b. unicellular organisms are more complex than multicelluar c. multicellular organisms can rid waste more efficiently d. multicellular organisms can divide the work into specialized cells 2 10/24/2013 What the Cell?! All cells have 4 things in common: Surrounded by a barrier = Cell Membrane Cytoplasm Ribosomes At some time, they contain DNA/RNA Molecules that store & transmit genetic info Cell Membrane: Phospholipid Bilayer Cytoplasm It is the part of a cell that is enclosed within the cell membrane. The cytoplasm is the site where most cellular activities occur, such as many metabolic pathways like glycolysis, and processes such as cell division. Schematic showing the cytoplasm, with major components of a typical animal cell Cytoplasm: Its Components 1. The cytosol is the portion of a cell that is not enclosed within membrane-bound organelles. It is a translucent fluid in which the other cytoplasmic elements are suspended. It makes up about 70 % of the cell volume and is composed of water, salts and organic molecules. 2. Organelles are membranebound compartments within the cell that have specific functions. What is an Organelle? Internal structure Enclosed in a membrane Thin layer of cover or lining Specific function (job) “Little Organ” Organelles What is a Nucleus? Large structure Enclosed in a membrane Thin layer of cover or lining Contains the cell’s DNA Controls many cell activities Nucleus 3 Nucleus An electron micrograph of a cell nucleus, showing the darkly stained nucleolus. The nuclear envelope is a double membrane that encloses the entire organelle and separates its contents from the cellular cytoplasm. The viscous liquid within it is called nucleoplasm, and is similar in composition to the cytosol found outside the nucleus. The nucleolus is a discrete densely stained structure found in the nucleus. Types of Cells Prokaryotes vs. Eukaryotes 10/24/2013 Venn Diagram of Cell Types Prokaryotes •No nucleus •Smaller •Simpler •Cell membrane •DNA •Carry out a variety of activities •Cytoplasm •Ribosomes Eukaryotes • Nucleus • Larger • Complex • Membrane-bound organelles Types of Cells Prokaryote Pro = No Eukaryote No nucleus. Genetic material NOT contained in a nucleus Nucleus that contains genetic material Generally smaller & simpler Generally larger & more complex. Have membrane-bound organelles. Bacteria Plants, Animals, Fungi, & Protists 4