Presentation on theme: "Chapter 7 Cellular Structure and Function. CELLS!"— Presentation transcript:
Chapter 7 Cellular Structure and Function
Chapter 7.1 Cell Discovery and Theory Robert Hooke observes the structures of cork (oak bark) and calls the units cells.
History of Cell Theory What did Anton Van Leeuwenhoek see through his microscope? He was surprised to find what looked like tiny animals. He named these animals “animalcules”.
How do you develop a theory?
Cell Theory 1.All living organisms are composed of one or more cells. 2.Cells are the basic unit of structure and organization of all living organisms. 3.Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.
Microscopes Review Figure 7.1 on page , Microscopes in Focus Why were there long periods between significant discoveries about cells? How Big?
Types of Microscopes 1.Compound Light Microscopes 2.Electron Microscopes a.Transmission Electron Microscope b.Scanning Electron Microscope c.Scanning Tunneling Electron Microscope Based on the names of these microscopes, how do you think each type magnifies objects?
Compound Light Microscope Uses series of glass lenses and visible light to produce a magnified image Specimens must be thin Specimens can be alive or dead Maximum magnification is 1000x
Compound Light Microscope
Calculating Total Magnification Compound light microscopes use a series of lenses to magnify; each lens magnifies the image For example, if eyepiece lens magnifies at 10x and the objective lens magnifies at 10x, the total magnification is 100x (10 X 10) What would the total magnification be if the eyepiece magnified at 10x and the objective lens magnified at 4x? Answer = 40 x = 10 X 4
Helpful Hints: Diaphragm Usage Course Adjustor v. Fine Adjustor – Location and purpose – Movement of stage Lowest power to highest power! – DON’T USE COURSE ADJUSTOR IN HIGH POWER!
Compound Light Microscope Microscope PartFunction Ocular (eyepiece) Nosepiece High Power Objective Lens Low Power Objective Lens Stage and Stage Clips Diaphragm Fine Adjustment Course Adjustment Base/Arm
Compound Light Microscope Microscope PartFunction Ocular (eyepiece)Used for viewing object; hold lens with 10x magnification NosepieceHolds objective lens High Power Objective LensLenses with magnification of 10x, 40x, 100x, or more Low Power Objective LensLens with magnification of 4x Stage and Stage ClipsHold microscope slide in place DiaphragmControls the light entering the field of view Fine AdjustmentBrings object into sharp focus Course AdjustmentBrings object into focus Base/ArmSupport for the microscope
Electron Microscopes – Uses beams of electrons to magnify images Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM) Scanning Tunneling Electron Microscope (STM) Aim a beam of electrons at a thin slice of cells Electrons are passed through a specimen to a screen Thick parts of the specimen absorb more electrons than thin parts forming a black-and-white shaded image of specimen Can magnify up to 500,000x Specimen must be dead, sliced thin, and stained Directs electrons over the surface of the specimen produces a three dimensional image Specimen must be nonliving Brings a charged tip of a probe extremely close to the specimen so that the electrons “tunnel” through the small gap between Creates a three- dimensional image Can use live specimens
Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM) Scanning Tunneling Electron Microscope (STM)
Transmission Electron Microscope Bacteriophages (viruses that infect bacteria)
Scanning Electron Microscope
Human atrial (heart) muscle
Scanning Electron Microscopy Stainless Steel Screen
Scanning Electron Miscroscopy Table Salt
Scanning Electron Miscroscopy Insect on the leg of a daddy long- leg spider
Scanning Electron Miscroscopy Eye of an Ant
Scanning Electron Miscroscopy Spider
Scanning Tunneling Microscope STM of DNA molecule
Quiz Tomorrow History of Cell Theory – Hooke and Van Leeuwenhoek Cell Theory Types of Microscopes – Electron Microscopes – Compound Light Microscopes Parts Functions Calculating total magnification (NOT Basic Cell Types)
Basic Cell Types What do all cells have in common? – Plasma Membrane (barrier controls what moves in and out of cell) – Genetic material
Basic Cell Types Prokaryotic CellsEukaryotic Cells Smaller Larger Contain no organelles Contain membrane-bound organelles – specialized structures that carry out specific cell functions No nucleus Contain nucleus to hold genetic material Bacteria Protists, Fungi, Plants, and Animals
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Function of Plasma Membrane Thin, flexible boundary between the cell and its environment Maintains homeostasis by controlling what enters and exits the cell – Allows nutrients to enter – Allows waste and other products to leave
Selective Permeability The plasma membrane allows some substances to pass through while keeping others out Controls how, when, and how much of these substances enter and leave a cell
Structure of the Plasma Membrane Most molecules in the membrane are lipids – Phospholipids containing Glycerol 2 fatty acids Phosphate group
Structure of Plasma Membrane
Structure of the Membrane “Phospholipid bilayer” – TWO layers of phospholipids – Interior is hydrophobic (water fearing) Non-polar fatty acid tails – Exterior is hydrophilic (water loving), polar Polar phosphate groups
Proteins Proteins are imbedded in the membrane. Transmit signals to the inside of the cell. Anchor the membrane to the internal support structure of the cell. Transport proteins act as tunnels for substances to enter and leave the cell. Cholesterol Cholesterol prevents fatty acid tails from sticking together. Carbohydrates Carbohydrates attach to the proteins. Identify the cell Identify chemical signals in the cell’s environment.
Cell Organelles Cell PartFunction CytoplasmSemfluid material that surrounds the organelles and provides a place for chemical reactions to take place. CytoskeletonA network of long, thin protein fibers that form a framework and support system for the cell; anchors all the organelles NucleusControl center of the cell; contains the cell’s DNA; surrounded by nuclear membrane (envelope) RibosomesProduces proteins NucleolusProduces ribosomes Endoplasmic reticulumFolded membrane system that is the site for protein and lipid production Smooth ERArea with no ribosomes attached; place where many carbohydrates and lipids are produced Rough ERRibosomes are attached and produce proteins
Cell Organelles Cell PartFunction Golgi ApparatusFlattened membranes that modified, sorts, and packages proteins VacuolesTemporary storage for the cell; used to store food, enzymes, and other materials needed for the cell LysosomesStructure containing enzymes used to digest waste CentriolesUsed in cell reproduction MitochondriaProduce energy by breaking down sugars ChloroplastsCapture light energy and convert it to chemical energy (food); found in plant cells Cell wallThick, rigid fibers that surround the plasma membrane and protects the cell Cilia and FlagellaUsed for cell movement in some eukaryotic cells
Chapter 7 Test History of Cell Theory – Hooke – Leeuwenhoek – Cell theory Microscopes – Light microscopes – Electron microscopes Prokaryotic & eukaryotic cells Plasma membrane – Selective permeability – Phospholipid bilayer Cell Organelles Function