6Cell Theory All living organisms are composed of one or more cells. Cells are the basic unit of structure and organization of all living organisms.Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.
7MicroscopesReview Figure 7.1 on page , Microscopes in Focus Why were there long periods between significant discoveries about cells? How Big?
8Types of Microscopes Compound Light Microscopes Electron Microscopes Transmission Electron MicroscopeScanning Electron MicroscopeScanning Tunneling Electron MicroscopeBased on the names of these microscopes, how do you think each type magnifies objects?
9Compound Light Microscope Uses series of glass lenses and visible light to produce a magnified imageSpecimens must be thinSpecimens can be alive or deadMaximum magnification is 1000x
11Calculating Total Magnification Compound light microscopes use a series of lenses to magnify; each lens magnifies the imageFor 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
12Helpful Hints: Diaphragm Usage Course Adjustor v. Fine Adjustor Location and purposeMovement of stageLowest power to highest power!DON’T USE COURSE ADJUSTOR IN HIGH POWER!
13Compound Light Microscope Microscope PartFunctionOcular (eyepiece)NosepieceHigh Power Objective LensLow Power Objective LensStage and Stage ClipsDiaphragmFine AdjustmentCourse AdjustmentBase/Arm
14Compound Light Microscope Microscope PartFunctionOcular (eyepiece)Used for viewing object; hold lens with 10x magnificationNosepieceHolds objective lensHigh Power Objective LensLenses with magnification of 10x, 40x, 100x, or moreLow Power Objective LensLens with magnification of 4xStage and Stage ClipsHold microscope slide in placeDiaphragmControls the light entering the field of viewFine AdjustmentBrings object into sharp focusCourse AdjustmentBrings object into focusBase/ArmSupport for the microscope
15Electron 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 cellsElectrons are passed through a specimen to a screenThick parts of the specimen absorb more electrons than thin parts forming a black-and-white shaded image of specimenCan magnify up to 500,000xSpecimen must be dead, sliced thin, and stainedDirects electrons over the surface of the specimenproduces a three dimensional imageSpecimen must be nonlivingBrings a charged tip of a probe extremely close to the specimen so that the electrons “tunnel” through the small gap betweenCreates a three-dimensional imageCan use live specimens
16Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM)Scanning Tunneling Electron Microscope (STM)
17Transmission Electron Microscope Bacteriophages (viruses that infect bacteria)
25Scanning Tunneling Microscope STM of DNA molecule
26Quiz Tomorrow History of Cell Theory Cell Theory Types of Microscopes Hooke and Van LeeuwenhoekCell TheoryTypes of MicroscopesElectron MicroscopesCompound Light MicroscopesPartsFunctionsCalculating total magnification(NOT Basic Cell Types)
27Basic Cell Types What do all cells have in common? Plasma Membrane (barrier controls what moves in and out of cell)Genetic material
28Basic Cell Types Prokaryotic Cells Eukaryotic Cells Smaller Larger Contain no organellesContain membrane-bound organelles – specialized structures that carry out specific cell functionsNo nucleusContain nucleus to hold genetic materialBacteriaProtists, Fungi, Plants, and Animals
33Function of Plasma Membrane Thin, flexible boundary between the cell and its environmentMaintains homeostasis by controlling what enters and exits the cellAllows nutrients to enterAllows waste and other products to leave
34Selective Permeability The plasma membrane allows some substances to pass through while keeping others outControls how, when, and how much of these substances enter and leave a cell
35Structure of the Plasma Membrane Most molecules in the membrane are lipidsPhospholipids containingGlycerol2 fatty acidsPhosphate group
38Structure of the Membrane “Phospholipid bilayer”TWO layers of phospholipidsInterior is hydrophobic (water fearing)Non-polar fatty acid tailsExterior is hydrophilic (water loving), polarPolar phosphate groups
40Other Components of the Plasma Membrane 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 prevents fatty acid tails from sticking together.Carbohydrates attach to the proteins.Identify the cellIdentify chemical signals in the cell’s environment.
42Cell Structures and Organelles Chapter 7.3Cell Structures and Organelles
43Cell Organelles Cell Part Function Cytoplasm Semfluid 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 organellesNucleusControl center of the cell; contains the cell’s DNA; surrounded by nuclear membrane (envelope)RibosomesProduces proteinsNucleolusProduces ribosomesEndoplasmic reticulumFolded membrane system that is the site for protein and lipid productionSmooth ERArea with no ribosomes attached; place where many carbohydrates and lipids are producedRough ERRibosomes are attached and produce proteins
44Cell Organelles Cell Part Function Golgi Apparatus Flattened membranes that modified, sorts, and packages proteinsVacuolesTemporary storage for the cell; used to store food, enzymes, and other materials needed for the cellLysosomesStructure containing enzymes used to digest wasteCentriolesUsed in cell reproductionMitochondriaProduce energy by breaking down sugarsChloroplastsCapture light energy and convert it to chemical energy (food); found in plant cellsCell wallThick, rigid fibers that surround the plasma membrane and protects the cellCilia and FlagellaUsed for cell movement in some eukaryotic cells
45Chapter 7 Test History of Cell Theory Microscopes HookeLeeuwenhoekCell theoryMicroscopesLight microscopesElectron microscopesProkaryotic & eukaryotic cellsPlasma membraneSelective permeabilityPhospholipid bilayerCell Organelles Function