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Similaire à Chap 6 lecture Part 1 with Audio
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Chap 6 lecture Part 1 with Audio
- 1. Chapter 6 A Tour of the Cell PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 2. Overview: The Importance of Cells • All organisms are made of cells • The cell is the simplest collection of matter that can live • Cell structure is correlated to cellular function • All cells are related by their descent from earlier cells Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 3. How do the different parts of a cell function separately and together? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 4. Concept 6.1: To study cells, biologists use microscopes and the tools of biochemistry • Though usually too small to be seen by the unaided eye, cells can be complex • Two important parameters of microscopy – Magnification- ratio of object image to real size – Resolution- clarity of the image • Light microscopes pass light through specimen and then through glass lenses – Resolution of 200 nanometers, i.e. small bacteria – Magnification 1000 times the actual size Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 5. LE 6-2 10 m Human height 1m Length of some nerve and muscle cells Unaided eye 0.1 m Chicken egg 1 cm Frog egg 1 mm Measurements Light microscope 1 centimeter (cm) = 10–2 meter (m) = 0.4 inch 100 µm 1 millimeter (mm) = 10–3 m 1 micrometer (µm) = 10–3 mm = 10–6 m Most plant and 1 nanometer (nm) = 10–3 µm = 10–9 m animal cells 10 µm Nucleus Most bacteria Mitochondrion Electron microscope 1 µm Smallest bacteria 100 nm Viruses Ribosomes 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms
- 6. Light Microscope Differential- Brightfield Interference- (unstained) Contrast (Nomarski) 50 µm Fluorescence Brightfield 50 µm (stained) Confocal Phase-contrast 50 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 7. LE 6-4 Electron Microscopes 1 µm Cilia Used to study subcellular structures Scanning electron microscopes (SEMs) focus a beam of electrons onto the surface of a specimen, providing images that look 3D Longitudinal Cross section section of of cilium cilium 1 µm Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen TEMs are used mainly to study the internal ultrastructure of cells
- 8. Isolating Organelles by Cell Fractionation • Cell fractionation takes cells apart and separates the major organelles from one another • Ultracentrifuges fractionate cells into their component parts Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 9. Isolating Organelles by Cell Fractionation 1000 g (1000 times the force of gravity) 10 min Supernatant poured into next tube Homogenization 20,000 g 20 min 80,000 g Tissue Homogenate 60 min cells Pellet rich in nuclei and 150,000 g cellular debris 3 hr Pellet rich in mitochondria Differential centrifugation chloroplasts if cells (and are from a plant) Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes) Cell fractionation enables Pellet rich in ribosomes scientists to determine the functions of organelles Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 10. Concept Check • How do the stains used for light microscopy compare with those used for electron microscopy? • Which type of microscope would you use to study… • Changes in the shape of a white blood cell? • Surface texture of hair? • Detailed structure of an organelle? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
- 11. The two types of cells Prokaryotic vs. Eukaryotic Cells Nucleus- no yes Membrane Bound organelles no yes Plasma membrane yes yes Cytosol yes yes Chromosomes yes yes Ribosomes yes yes Domain Bacteria, Archea protist ,fungi, plant animal
- 12. LE 6-6 Pili Nucleoid Ribosomes Plasma membrane Cell wall Bacterial chromosome Capsule 0.5 µm Flagella A typical A thin section through the rod-shaped bacterium Bacillus bacterium coagulans (TEM)
- 13. LE 6-7 Surface area increases while Total volume remains constant Larger organisms do not have larger cells- simple more cells 5 1 1 Total surface area (height x width x 6 150 750 number of sides x number of boxes) Total volume (height x width x length 1 125 125 X number of boxes) Surface-to-volume ratio 6 1.2 6 (surface area ÷ volume)
- 14. The boundary of every cell – Plasma membrane Outside of cell Carbohydrate side chain Hydrophilic region Inside of cell 0.1 µm Hydrophobic region Hydrophilic Phospholipid Proteins region TEM of a plasma membrane Structure of the plasma membrane Function - selective barrier that allows sufficient passage of oxygen, nutrients, and waste Structure - double layer of phospholipids
- 15. A Panoramic View of the Eukaryotic Cell ENDOPLASMIC RETICULUM (ER Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin In animal cells but not Centrosome Plasma membrane plant cells: Lysosomes CYTOSKELETON Centrioles Microfilaments Intermediate filaments Flagella (in Microtubules some plant Ribosomes: sperm) Microvilli Golgi apparatus Peroxisom e Mitochondrion Lysosome
- 16. Nuclear A Panoramic View of the Eukaryotic Cell envelope Rough NUCLEUS Nucleolus endoplasmic reticulum Chromatin Smooth Centrosome endoplasmic reticulum Ribosomes (small brown dots) Central vacuole Golgi apparatus Microfilaments Intermediate CYTOSKELETON filaments Microtubules In plant cells but not animal cells: Mitochondrion Chloroplasts Peroxisome Plasma Chloroplast membrane Central vacuole and Cell wall tonoplast Plasmodesmata Wall of adjacent cell Cell wall Plasmodesmata
- 17. Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions • A eukaryotic cell has internal membranes that partition the cell into organelles – Nucleus – contains most of the DNA – Ribosomes – use info from DNA to make proteins – Endomembrane system – variety of tasks, protein synthesis, transport, lipid metabolism, detoxification – Lysosyme – digest macromolecules – Vacuoles – Mitochondria – cellular respiration – Chloroplasts - photosynthesis Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Notes de l'éditeur
- LMs can magnify effectively to about 1,000 times the size of the actual specimen. Various techniques enhance contrast and enable cell components to be stained or labeled. Most subcellular structures, or organelles, are too small to be resolved by a LM.
- Cell fractionation takes cells apart and separates the major organelles from one another. Ultracentrifuges fractionate cells into their component parts. Cell fractionation enables scientists to determine the functions of organelles. Isolating Organelles by Cell Fractionation. Cell fractionation enables the researcher to prepare specific components of cells in bulk quantity to study their composition and functions. By following this approach, biologists have been able to assign various functions of the cell to the different organelles, a task that would be far more difficult with intact cells. For example, one cellular fraction collected by centrifugation has enzymes that function in the metabolic process known as cellular respiration. The electron microscope reveals this fraction to be very rich in the organelles called mitochondria. This evidence helped cell biologists determine that mitochondria are the sites of cellular respiration. Cytology and biochemistry complement each other in correlating cellular structure and function.