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Light Microscopes and Electron Microscopes: A Comparison

Explore the differences between light microscopes and electron microscopes, their advantages and disadvantages, and their applications in studying cells and organelles.

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Light Microscopes and Electron Microscopes: A Comparison

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  1. Cells

  2. Microscopy LIGHT REFRACT • Light Microscopes (Compound Light Microscopes) • Visible _______________ passed through the specimen then through glass lenses. The lenses __________ (bend) light so the image is magnified for vision. • Advantages: __________, _________ organisms, 1000x magnification • Disadvantages: Light microscope cannot resolve detail finer than _____ nm, can’t see small _______________ • Electron Microscopes (Scanning EM- _______________of specimen and Transmission EM- _______________ parts) • Focus a beam of _______________through specimen or onto its surface. • Advantages: Practical resolution limit is about 2nm (100x improvement over LM), can view detail of surface, 1000x more magnification than LMs • Disadvantages: only _______________organisms (vacuum packed), no color COLOR LIVING 200 ORGANELLES SURFACE INTERNAL ELECTRONS DEAD

  3. http://www.mos.org/sln/sem/semphoto.gif http://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Optical_microscope_nikon_alphaphot_%2B.jpg/220px-Optical_microscope_nikon_alphaphot_%2B.jpg

  4. Cell Fractionation ORGANELLES • Definition: technique used to take cells apart and separate the major _______________ from one another. • Tool: _______________. • Example: Separating cell parts in a tissue ULTRACENTRIFUGE

  5. Discovery of the Cell • The cell was discovered soon after the invention of the microscope in the 17th century. • Robert ___________ used the term “cell” when he examined cork because they looked like ___________ cells. HOOKE PRISON http://www.nndb.com/people/356/000087095/robert-hooke-1.jpg http://biology.clc.uc.edu/fankhauser/Labs/Cell_Biology/Cells_Lab/cork_100x_PA021953c.JPG

  6. Cell Theory LIFE • Cells are the smallest unit of _____. • All living things consist of cell(s) (Unicellular v. multicellular) • All cells come from __________________ cells, by division (mitosis or binary fission). Cannot “make” cells from _______________ chemicals. PRE-EXISTING NON-LIVING

  7. SURVIVE

  8. Unicellular Organisms FUNCTIONS • The single cell must carry out all __________ of life • As a result, cells of unicellular organisms are usually ______ complex that most cells of multicellular organisms. • Examples: amoeba, bacteria, paramecium MORE http://images.tutorvista.com/content/feed/u2077/Multicellular%20Organisms.jpg http://www.enchantedlearning.com/agifs/Amoeba_bw.GIF

  9. Functions of Life NUTRITION METABOLISM • ___________- obtaining food for energy and growth • _______________- chemical reactions such as cell respiration • ___________- an irreversible increase in cell size • _______________- perceiving and responding to changes in environment • ______________- keeping conditions inside the organism within tolerable limits • _______________- producing offspring sexually or asexually GROWTH RESPONSE HOMEOSTASIS REPRODUCTION http://tcdn.teacherspayteachers.com/thumbitem/Characteristics-of-Living-Things-Foldable/original-57634-2.jpg

  10. E. Coli as a Prokaryotic Cell

  11. Liver Cell as a Eukaryotic Cell

  12. Size of Cells 10-3 10-6 10-9 • SI unit for length is the meter (m) • mm (___) um (___) nm (___) • Examples • Surface area to volume ratios in cells • As objects increase in size, its volume grows at a faster rate than its surface area. • Formulas: V= SA= E3 6E2 http://www.xaraxone.com/webxealot/workbook19/cube_04.gif

  13. Surface Area of Cells (cont) MEMBRANE CELL VOLUME • The plasma _______________ controls the amount of oxygen, nutrients, and wastes to enter and exit the cell. If the _______________is too large, not the whole cell may be serviced. • Therefore, most cells are very _______ so there is a sufficient surface area to accommodate ________. • __________ organisms don’t usually have larger cells but rather a larger _______ of cells. SMALL VOLUME LARGER NUMBER http://mrswolfgang.wikispaces.com/file/view/brauerwoodsoncellsize.JPG/58621590/587x442/brauerwoodsoncellsize.JPG

  14. Parts of the nucleus • Nuclear Envelope- • Nuclear lamina- • Nuclear pores- • Chromosomes- • Chromatin- • _______________ (not membrane enclosed) - appears through the EM as a mass of _______ stained granules and fibers adjoining part of the chromatin. Location of rRNA ____________. NUCLEOLUS DENSELY SYNTHESIS

  15. Ribosomes RIBOSOMES • Cells with high rates of protein synthesis have a larger number of ____________ and more nucleoli. Ex. Pancreas cell • _______ ribosomes- are suspended in the cytosol • _________ ribosomes- are attached to the outside of the endoplasmic reticulum or nuclear envelope. FREE BOUND http://iws.collin.edu/biopage/faculty/mcculloch/1406/outlines/chapter%207/rougher2.jpg

  16. Endomembrane System EUKARYOTIC • Endoplasmic reticulum- network of membranes that accounts for more than half the membrane in many _______________ cells. • ER is a network of _____________- tubules and sacs. • ER _______- cisternal space from the cytosol. CISTERNAE LUMEN http://www.science-art.com/gallery/52/52_10202008105023.jpg

  17. RIBOSOMES Rough Endoplasmic Reticulum (surface has ___________) PROTEINS Functions • Make secretory _______________that specialized cells can use and release. • Example: • _________ factory: grows in place by adding membrane proteins and phospholipids to its own membrane. PANCREAS SECRETING INSULIN INTO BLOOD MEMBRANE http://epiehonorsbiology.wikispaces.com/file/view/ROUGH_ER!!!!!!.jpg/276281726/ROUGH_ER!!!!!!.jpg

  18. RIBOSOMES Smooth ER- lacks ________ SYNTHESIS • Functions • ____________ of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons. • ___________ in the smooth ER help in these processes • Also stores calcium ions that can ________ different responses. • Ex: when a muscle cell is _______________by a nerve impulse, calcium ions rush from the ER lumen into the cytosol and trigger muscle _______________. ENZYMES TRIGGER STIMULATED CONTRACTION http://ars.els-cdn.com/content/image/1-s2.0-S0143416002001823-gr2.jpg

  19. RECEIVING Golgi apparatus: Shipping and ___________ center MANUFACTURING PRODUCTS SENT • center of _______________, warehousing, sorting, shipping. • Location where _______________of the ER are modified, stored and ________ to other destinations. • Structure: consists of flattened unconnected _______________that look like a stack of _______________. • Contains two poles: ___ face and ____ face. • Cis face: _______________department that is located near the ER. Vesicles from the ER can fuse with the cis face of the Golgi. • Trans face: _______________ department. Cisternae move from a cis to trans directions and allow vesicles to pinch off to travel to other sites. • Cisternal maturation model: Golgi is a dynamic structure that progress forward from the cis to the trans face of the Golgi, carrying and _______________their protein cargo as they move. CISTERNAE PITA BREAD CIS TRANS RECEIVING SHIPPING MODIFYING

  20. Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html See a Golgi movie

  21. http://creationrevolution.com/wp-content/uploads/2010/11/Golgi-Apparatus-and-ER.jpghttp://creationrevolution.com/wp-content/uploads/2010/11/Golgi-Apparatus-and-ER.jpg

  22. Lysosomes: Digestive Compartments HYDROLYTIC ACIDIC • a membranous sac of _______________enzymes that an animal cell uses to digest macromolecules. • Lysosomal enzymes work best in the ______ surroundings of a lysosome and if it bursts, the enzymes are not very active due to the ______ pH of the cytosol. • _______________- process of engulfing smaller organisms or food particles • Food _________ fuses with a lysosome whose enzymes digest food. • _______________- damaged ___________ becomes surrounded by a membrane and lysosome fuses with it, breaking it down to monomers and returning to cytosol for reuse. NEUTRAL PHAGOCYTOSIS VACUOLE AUTOPHAGY ORGANELLE http://images.tutorvista.com/content/feed/u303/lysosomes%20secondary.gif

  23. http://2.bp.blogspot.com/_guSOnFRs_Ks/TJdlF8WZs6I/AAAAAAAAANg/uJiQqzioAEM/s1600/Lysosome-Functions1.jpghttp://2.bp.blogspot.com/_guSOnFRs_Ks/TJdlF8WZs6I/AAAAAAAAANg/uJiQqzioAEM/s1600/Lysosome-Functions1.jpg

  24. Vacuoles HYDROLYSIS LYSOSOMES • Vacuoles carry out ____________and are similar to ____________. • Other functions: • Food Vacuoles- form by _______________ • Contractile vacuoles- pump excess water out of the cell • Ex.: • Plant Cells: • Central vacuole enclosed by a membrane called ___________. • *Central vacuole develops by fusing ________ vacuoles • *Tonoplast is selective in _______________ solutes *cell sap- solution inside vacuole differs than cytosol PHAGOCYTOSIS FRESH WATER ALGAE TONOPLAST SMALLER TRANSPORTING http://middletownhighschool.wikispaces.com/file/view/plantcell450.jpg/98794271/plantcell450.jpg

  25. Vacuoles (cont) PROTEINS • Uses: • Holds reserves of important organic compounds such as _______________. • Plant cell’s main __________ area of inorganic ions such as K+ and Cl- • Can be used as __________ sites for metabolic by-products that would damage if kept in cytosol. • Some contain __________ that color the cell • Can protect plant by releasing _______________ • Major role in _________ as they absorb water to allow cells to grow without increasing ____________. STORAGE DISPOSAL PIGMENTS POISONS GROWTH CYTOPLASM http://24.media.tumblr.com/tumblr_m4lz7amz5V1qj8btco1_500.jpg

  26. Mitochondria METABOLIC ATP OXYGEN EUKARYOTIC • Mitochondrion: sites of cellular respiration, a __________ process that generates ____ by extracting energy from sugars, fats, other fuels with the help of __________. • Found in almost all ____________ cells. • The number of mitochondria is directly related with the cells ___________ activity. More active cells have _______ mitochondria. • Enclosed by two ____________, each a phospholipid bilayer with a unique collection of embedded _________. METABOLIC MORE MEMBRANES PROTEINS http://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Animal_mitochondrion_diagram_en_(edit).svg/400px-Animal_mitochondrion_diagram_en_(edit).svg.png http://microbewiki.kenyon.edu/images/thumb/2/25/Mitochondria.gif/400px-Mitochondria.gif

  27. Appearace SMOOTH • Outer membrane is __________ • Inner membrane has many folds (__________) • Two Compartments • Intermembrane space- in between inner and outer membrane • Mitochondrial __________contains: • __________- catalyze cellular respiration • Ribosomes- proteins attach to the cristae • mitochondrial _____ • Mitochondria are __________: changeable, moving, and growing. CRISTAE http://preview.turbosquid.com/Preview/2011/06/09__04_44_22/Mitochondria.jpga25b5219-8803-43de-9a20-d001b44f9f9eLarge.jpg MATRIX ENZYMES DNA DYNAMIC

  28. PLASTIDS Chloroplasts (of the organelle family (________) CAPTURE CHLOROPHYLL • Chloroplasts are the organelle in plants that _________ light energy • They contain ______________ (green pigment) which gives plants a green _______. • Contents of a Chloroplast • __________- flattened interconnected sacs (stacked like poker chips) • __________- stack of thylakoids • __________- fluid outside the thylakoids • Contains: • Chloroplasts are dynamic: changeable, moving, and growing. COLOR THYLAKOIDS GRANUM STROMA ENZYMES RIBOSOMES CHLOROPLAST DNA

  29. http://www.ftexploring.com/photopics/thylakoid1-50.gif

  30. Peroxisomes PEROXIDE • Contain enzymes that transfer hydrogen to oxygen to produce hydrogen __________. • Can detoxify alcohol, poison, etc. by transferring hydrogen to oxygen. • Importance of being membrane bound? http://www.facstaff.bucknell.edu/kfield/organelles/organelleimages/peroxisome.gif

  31. Cytoskeletonhttp://www.diffen.com/difference/Cilia_vs_FlagellaCytoskeletonhttp://www.diffen.com/difference/Cilia_vs_Flagella http://static.diffen.com/uploadz/d/d2/Cilia-vs-Flagella.png http://static.diffen.com/uploadz/d/d2/Cilia-vs-Flagella.png

  32. CILIA Many short WHAT’S THE DIFFERENCE? FLAGELLA Animation from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm • Few • Long

  33. Extracellular Components SHAPE • Cell Wall of Plant Cells • Purpose: to protect the cell, maintain its __________, and prevent excessive water uptake. • __________________: intercellular junction that allows cytosol to pass through and connect the chemical environments of _________________cells. • Water, small solutes (some proteins and RNA) can pass from cell to cell by moving along fibers of _______________to the plasmodesmata. PLASMODESMATA NEIGHBORING CYTOSKELETON What are cell walls of other organisms made of? Bacteria: PEPTIDOGLYCAN Fungi: PEROXIDE

  34. Extracellular Matrix (ECM) of Animal Cells

  35. Chapter 7 Animation from: http://www.sp.uconn.edu/~terry/images/anim/fluidmem.gif Click here to seeFluidityAnimation

  36. Cell membrane picture • http://www.ibguides.com/images/biology/2.4.1.png

  37. DIFFERENT Cell membranes MOVE! MOVING CHANGING Cell membranes contain many __________ molecules which are constantly ________________ and ________________.

  38. PROPERTIES __________of the Plasma membrane NONLIVING • Boundary- Separates the living cell from the __________ environment • Selectively ____________- allows some substances to cross more easily than other substances PERMEABLE http://www.greetin.gs/phoebecell/photogallery/zz4.gif http://www.mansfield.ohio-state.edu/~sabedon/054semip.gif

  39. Fluid Mosaic Model PROTEINS PHOSPHOLIPIDS • Two of the main parts of membranes are lipids and __________ (carbohydrates are also important). • ________________- most abundant lipid in membranes • _____________molecule- it has both a hydrophilic region and hydrophobic region • The cell membrane is a __________ structure (always moving) with a “mosaic” (assortment) of various proteins embedded in or attached to a bilayer of phospholipids AMPHIPATHIC DYNAMIC http://images.tutorvista.com/content/feed/u544/fluid_%20mosaic_model.jpg www.youtube.com/watch?v=ULR79TiUj80

  40. Fluidity of Membranes HYDROPHOBIC • Membranes are held together mainly by ____________interactions which are much weaker than covalent bonds. • Most of the lipids and proteins can move about __________- in the plane of the membrane • Cholesterol within the membrane reduces __________at moderate temperatures by reducing phospholipid movement and can hinder _______________ at lower temperatures therefore it is considered a “cholesterol buffer.” • membrane fluidity • movement LATERALLY FLUIDITY SOLIDIFICATION http://oregonstate.edu/instruct/bb451/summer12/stryer7/CH12/figure_12_33.jpg

  41. Membrane Proteins- 2 Types INTEGRAL • __________ proteins- penetrate the hydrophobic core of the lipid bilayer and many are transmembrane proteins which completely span the membrane. • ____________ region- consist of one or more stretches of nonpolar amino acids • ____________ region- exposed to the aqueous solutions of both sides of the membrane • ____________ proteins- not embedded in the lipid bilayer and instead are _______________ loosely bound to the surface of the membrane HYDROPHOBIC HYDROPHILIC PERIPHERAL APPENDAGES http://oregonstate.edu/instruct/bb451/winter12/stryer6/CH12/figure12-17.jpg

  42. Cell-Cell Recognition DISTINGUISH • A cell’s ability to ____________one type of cell from another • Example: Sorting of cells into tissues and organs in an animal embryo. • Example: Rejection of foreign cells by the ____________ system. • How do cells recognize each other? • Bind to surface molecules (_________________) on the plasma membrane. • ____________- form when carbohydrates bond covalently to lipids. • ________________- form when carbohydrates bond covalently to proteins. IMMUNE CARBOHYDRATES GLYCOLIPIDS GLYCOPROTEINS http://www.quia.com/files/quia/users/lmcgee/membranetransport/cell-cell-recognition.gif

  43. More on Permeability DISSOLVE • Due to the lipid bilayer, nonpolar molecules can ____________in the lipid bilayer and cross with ease • The hydrophobic core of the membrane ____________the direct passage of ions and polar molecules through the membrane • Proteins in the membrane play a key role in ____________of these hydrophilic molecules. IMPEDES TRANSPORT

  44. Other Functions • Hormone binding sites • Immobilized Enzymes • Cell adhesion • Channels for passive transport • Pumps for active transport MORE SOON

  45. Passive Transport DIFFUSION ENERGY DIFFUSION • Passive Transport • Definition: the ____________of a substance across a membrane with no ____________ investment • ____________: the tendency for molecules to spread out evenly into available space ( NO ENERGY REQUIRED. • Rule of diffusion: movement from ____________ concentration to ____________ concentration. • Concentration gradient- gradual difference in the ____________of solutes in a solution causing movement from a higher to lower concentration. • ____________: diffusion of water • Example: p. 132Water moves from the lower solute concentration (more free water) to the higher solute concentration (less free water) until free water concentration is _______. HIGH LOW CONCENTRATION OSMOSIS EQUAL

  46. ISOTONIC HYPOTONIC • Water balance • ____________: the concentration of water in the cell and the environment is the same. No water movement. • ____________: the concentration of water in the cell is greater than that of the environment. Water will move ____________ the cell into the environment. • ____________: the concentration of water in the cell is less than that of the environment. Water will move from the environment ____________ the cell. • Example: p. 133 How does that affect cells with/without cell walls. • osmosis 1 • osmosis 2 OUTSIDE HYPERTONIC INTO

  47. Facilitated Diffusion PASSIVE SPECIFIC • Definition: ____________ transport with the help of transport proteins. • Most transport proteins are ____________ and only transport particular substances • Two types of transport proteins: • ____________ proteins provide corridors that allow molecules to cross the membrane • ion channels function as gated channels which rely on a stimulus that causes them to open or close. • ____________ proteins undergo a change in shape that translocates the solute-binding site across the membrane. The change in shape may be triggered by the binding and release of the transported molecule. CHANNEL CARRIER

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