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Transcript
7.1 Life is Cellular • Janssen 1590 Invented the first compound microscope Discovery of Cells Robert Hooke (1665) - English Scientist - used a light microscope to observe cork (dead plant cells) - observed many small “boxes” and named them cells Cell Wall Anton van Leeuwenhoek - 1674 • Dutch Lens Maker • Looked at pond water under a microscope and saw green, single cell organisms moving around! • Also looked at teeth scrapings through his microscope and noticed bacteria. VOLVOX UNDER DARK FIELD Robert Brown (1832) • Botanist • Identified cell nuclei Matthias Schleiden (1838) • Suggested that plants are composed of cells! Theodor Schwann (1839) • German Physiologist • Stated that the cell was the basic unit of structure in animals. Rudolf Virchow (1855) • German Doctor • Stated that new cells come from existing cells –Cells divide to make more Ernst Ruska (1939) • Won the Nobel Prize in physics for electron optics. –Invented the electron microscope Compound Light Microscope • Description – Most common microscope – Uses two lenses and light to view specimen • Maximum Magnification – Up to 1500x • Image of Specimen – Allows you to view specimen that light can pass through. Compound Light Microscope • Benefits – Most affordable – Can be used to view living specimen – Easy to use • Disadvantages – Limited magnification – Requires light to function – Must stain some specimen in order to see them. (No longer alive) Scanning Electron Microscope (SEM) • Description – Shoots electrons at a specimen and collects them as they bounce off the surface of organisms • Helps scientists study the exterior structure of specimen. • Maximum Magnification • Up to 500,000x magnification • Description of Image – Used to view exterior structures in great detail. – Images are viewed on a developed film or computer screen Scanning Electron Microscope (SEM) • Benefits – Very high magnification and detailed images. Able to view the exterior structures of the specimen in 3D. • Disadvantages – Can only view dead or nonliving specimen. Difficult to prepare specimen for viewing. Very expensive to purchase and maintain. • Bounces electrons off specimens to study SURFACE structures. Simple but Amazing SEM images Dentist Drill Velcro Split end of a hair Mites on skin Scanning Electron Microscope •A scanning electron microscope picture of a nerve ending. It has been broken open to reveal vesicles (orange and blue) containing chemicals used to pass messages in the nervous system. Transmission Electron Microscope (TEM) • Electrons pass through specimens to study the INTERIOR structures Transmission Electron Microscope (TEM) • Description – Shoots electrons through specimens – Allows scientists to study the INSIDE of specimen at great detail. • Maximum Magnification – Up to 5,000,000x magnification • Description of Image – Used to view interior structures of the specimen in great detail. – Images are viewed on a developed film or computer screen Transmission Electron Microscope (TEM) • Benefits – Very high magnification and detailed images. Able to view interior structures of the specimen. • Disadvantages – Can only view dead or non-living specimen. Difficult to prepare specimen for viewing. Very expensive to purchase and maintain. 2D images only. Transmission Electron Microscope Transmission Electron Microscope 7.2 Cell Structure Lesson Overview Lesson Overview Life Is Cellular The Discovery of the Cell The Cell Theory: 1. All living things are made up of cells. 2. Cells are the basic units of structure and function in living things. 3. New cells are produced from existing cells. Prokaryotes and Eukaryotes – Prokaryote = • Cell that do not contain a nucleus or nucleus membrane bound organelles. – Eukaryote= organelles • Cells that contain a nucleus and cell membrane membrane bound organelles. Lesson Overview Life Is Cellular Prokaryotes and Eukaryotes Lesson Overview Life Is Cellular Prokaryotes • Prokaryotic cells are generally smaller and simpler than eukaryotic cells. • They are SIMPLE yet, still fully alive!! • Example: Bacteria Lesson Overview Life Is Cellular Eukaryotes • Eukaryotic cells are generally larger and more complex. • Most contain dozens of structures and internal membranes. • Many eukaryotes are highly specialized. • Types of eukaryotes: plants, animals, fungi, and Protists. Cell Diversity Size Shape Function Location Parts Cell Diversity Figure 3.7; 1, 2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.19a Cell Diversity Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.19b Differences between Plant Cells and Animal Cells Plant Cell: •Cell wall •Large central vacuole •Chloroplasts •Box-like shape Animal Cell: •No cell wall •Many small vacuoles •No chloroplasts •Rounded shape Life Is Cellular Cell Organization Lesson Overview Eukaryotic cells can be divided into two major parts: • Nucleus • Cytoplasm. Prokaryotic cells have cytoplasm, but not a nucleus Life Is Cellular Cell Organization Lesson Overview • Organelles – specialized structure that performs important functions within a cell. • Literally “Little Organ” • Similar to a body organ!! Lesson Overview Life Is Cellular Cell Structure The Nucleus • Cellular Control Center • Contains DNA (Genetic Information) • Prokaryotic – DNA is in cytoplasm • Three main parts • Nucleolus • Nuclear envelope • Chromatin Lesson Overview Life Is Cellular Cell Structure Nuclear Envelope • Membrane that surrounds the nucleus • Controls what enters and exits! Lesson Overview Life Is Cellular Cell Structure Chromatin • DNA bound to proteins and condensed. Lesson Overview Life Is Cellular Cell Structure Nucleolus • Small dense region in the nucleus. • Creates ribosome Cell Structure Cytoplasm Mostly H20 and Nutrients Suspends organelles - fills up all the space between the cell membrane and nucleus. Lesson Overview Life Is Cellular Cell Structure Vacuoles • Membrane enclosed structure that is used to store materials. » Ex: water, salts, proteins, and carbohydrates. Lesson Overview Life Is Cellular Cell Structure Vesicle • Small membrane-enclosed structures used to move materials between organelles, as well as to and from the cell surface. Lesson Overview Life Is Cellular Cell Structure Lysosome • Small organelles filled with enzymes that breakdown and recycle organic molecules or harmful bacteria. • “Waste” removal crew for the cell. Lesson Overview Life Is Cellular Cell Structure Ribosome • Small organelles that produce proteins. • Found in the cytoplasm and on the ER Lesson Overview Life Is Cellular Cell Structure Endoplasmic Reticulum • Internal membrane system • Assembles lipids, proteins and other materials • Known as the “ER” Lesson Overview Life Is Cellular Cell Structure Rough Endoplasmic Reticulum • Has ribosomes all over its surface. • Involved in the production of proteins Lesson Overview Life Is Cellular Cell Structure •Smooth Endoplasmic Reticulum • NO ribosomes on its surface. »Production of membrane lipids. »Detoxification of chemicals. Lesson Overview Life Is Cellular Cell Structure Golgi Apparatus • Appears as a stack of flattened membranes. • Modifies, packages, and ships proteins and lipids around the cell or out of the cell. Lesson Overview Life Is Cellular Cell Structure • From the Golgi apparatus, proteins or lipids are “shipped” to their final destination inside or outside the cell. Lesson Overview Life Is Cellular Cell Structure Mitochondria • The power plant of the cell. • Converts chemical energy stored in food (glucose) into useable energy! Lesson Overview Life Is Cellular Cell Structure Chloroplasts • Captures light energy and converts it into food (glucose). • Only in plant cells! • Photosynthesis Lesson Overview Life Is Cellular Cell Structure Cytoskeleton • Tough and flexible framework that supports the cell. • Made of protein • Plays a role in cell division. CellCell Structure Wall Cell Wall • Outer-most layer of plant cells • Protects, supports, and maintains the shape of plant cells. – Made of cellulose, pectin and lignin Lesson Overview Life Is Cellular Cell Structure Cell Membrane What is the function of the cell membrane? • It is the cell’s gate keeper!! • Regulates what enters and leaves the cell. • The cell membrane is Selectively Permeable • Some substances can cross the membrane easily, while others cannot! Lesson Overview Cell Membrane Life Is Cellular • Cell membranes are made of double-layer of Phospholipids. • Called the phospholipid bilayer. • This makes the membrane a strong and flexible barrier between the cell and its surroundings. Lesson Overview Life Is Cellular The Properties of Lipids Phospholipid Review • Fatty acid portions of such a lipid are hydrophobic, or “water-hating” • The opposite end of the molecule is hydrophilic, or “water-loving.” Lesson Overview Life Is Cellular The Properties of Lipids • The hydrophobic fatty acid “tails” cluster together • The hydrophilic “heads” are attracted to water. • A lipid bilayer is the result. Lesson Overview Life Is Cellular The Fluid Mosaic Model • There are also carbohydrates and proteins embedded in the membrane. • The membrane contains several different molecules, but remains flexible (Like a liquid) Cell Structure Special Structures on some cell membranes Cilia - Movement or to moves materials across the cell surface. Flagellum - propel the cell. Cilia Flagella Slide 3.18 Cilia vs. Flagella Movement