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Cell Architecture “Of the things of nature there are … two kinds: those which are brought into being and perish, and those which are free from these processes throughout all ages. The latter are of the highest worth and are divine… Aristotle 384-322 BC from Parts of Animals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Techniques to view cells & fractionate cellular components -Microscopy - Differential Centrifugation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-2 10 m Human height 1m When object becomes too small to see by eye ~1 mm Length of some nerve and muscle cells 0.1 m Chicken egg When is resolving power or resolution important? 1 cm When details become blurry= the difference between two points is unclear Frog egg 1 mm 100 µm Most plant and animal cells Nucleus Most bacteria 1 µm What is the relationship between resolution and Mitochondrion Wavelength ) of light (electromagnetic spectrum)? Smallest bacteria PowerPoint Lectures for Biology, Seventh Edition Higher resolution (more details) at shorter 100 nm Neil Campbell and Jane Reece 10 nm Viruses Ribosomes Proteins Lipids 1 nm Small molecules Lectures by Chris Romero 0.1 nm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Atoms Electron microscope 10 µm Light microscope Measurements 1 centimeter (cm) = 10–2 meter (m) = 0.4 inch 1 millimeter (mm) = 10–3 m 1 micrometer (µm) = 10–3 mm = 10–6 m 1 nanometer (nm) = 10–3 µm = 10–9 m Unaided eye When is magnification important? LE 6a Forms of Light Microscopy Brightfield What is different about (a) vs (b)? Brightfield PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Phase-contrast Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 50 µm LE 6-3b Differential-interference-contrast (DIC) (Nomarski) Fluorescence (Specific structures labeled with fluorescent tag) 50 µm Confocal PowerPoint Lectures for Biology, Seventh Edition (laser beam) Neil Campbell and Jane Reece Any difference? Lectures by Chris Romero Conventional fluorescence Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-4 Cilia Scanning electron microscopy (SEM) 1 µm Surface of rabbit tracheal cells (cilia) Transmission electron microscopy (TEM) Longitudinal section of cilium PowerPoint Lectures for Section of tracheal Biology, Seventh Edition tissue Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cross section of cilium 1 µm Surface area increases while Total volume remains constant LE 6-7 Why do cells tend to be small? 5 1 1 Total surface area (height x width x number of sides x number of boxes) 6 150 750 Total volume (height x width x length PowerPoint Lectures for X number of boxes) 1 125 125 6 1.2 6 Biology, Seventh Edition Neil Campbell and Jane Reece Surface-to-volume ratio (surface by area volume) Lectures Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Isolating Organelles by Cell Fractionation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-5a Homogenization Tissue cells PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Differential centrifugation Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Homogenate LE 6-5b 1000 g (1000 times the force of gravity) 10 min Supernatant poured into next tube 20,000 g 20 min 80,000 g 60 min Pellet rich in nuclei and cellular debris 150,000 g 3 hr Pellet rich in mitochondria (and chloroplasts if cells are from a plant) PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes) Pellet rich in ribosomes Cells Exhibit Evolutionary Relatedness by their Similarities & Differences Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-6 Pili Nucleoid Ribosomes Plasma membrane Bacterial chromosome Cell wall Capsule 0.5 µm Flagella Prokaryote PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece A typical rod-shaped bacterium Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A thin section through the bacterium Bacillus coagulans (TEM) ENDOPLASMIC RETICULUM (ER LE 6-9a Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON Microfilaments Intermediate filaments Microtubules Ribosomes: Microvilli PowerPoint Lectures for Biology, Seventh Edition Golgi apparatus Peroxisome Neil Campbell and Jane Reece Mitochondrion Non-plant cell Lectures by Chriseukaryotic Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm) Nuclear envelope LE 6-9b NUCLEUS Nucleolus Rough endoplasmic reticulum Chromatin Smooth endoplasmic reticulum Centrosome Ribosomes (small brown dots) Central vacuole Golgi apparatus Microfilaments Intermediate filaments Microtubules CYTOSKELETON Mitochondrion Peroxisome Chloroplast Plasma PowerPointmembrane Lectures for Biology, SeventhCellEdition wall Neil Campbell and Jane Reece Plasmodesmata Wall of adjacent cell Plant cellRomero Lectures by Chris Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata • Basic features of ALL cells: – Plasma membrane – Semifluid substance called the cytosol – Chromosomes (carry genes) – Ribosomes (make proteins) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-8 Plasma membrane Outside of cell Carbohydrate side chain Hydrophilic region Inside of cell 0.1 µm Hydrophobic region PowerPoint Lectures for Biology, Seventh Edition Hydrophilic Neil Campbell and Jane Reece region TEM of aby plasma Lectures Chrismembrane Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipid Proteins Structure of the plasma membrane LE 6-10 Nucleus Nucleus 1 µm Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear envelope PowerPoint Lectures for 0.25 µm Biology, Seventh Edition Ribosome Neil Campbell and Jane Reece 1 µm Close-up of nuclear envelope Lectures by Chris Romero Pore complexes (TEM) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nuclear lamina (TEM) LE 6-12 Smooth ER Nuclear envelope Rough ER ER lumen Cisternae Ribosomes Transitional ER Transport vesicle Smooth ER PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Rough ER 200 nm Functions of Smooth ER • The smooth ER – Synthesizes lipids – Metabolizes carbohydrates – Stores calcium – Detoxifies poison Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Functions of Rough ER • The rough ER – Has bound ribosomes that make proteins targeted for membranes or to be transported across membranes – Is a membrane factory for the cell Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-11 Ribosomes ER Cytosol Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes TEM showing ER and ribosomes PowerPoint Lectures for Biology, Seventh Edition Large subunit Small subunit 0.5 µm Neil Campbell and Jane Reece Part of protein synthesis machinery Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ribosome LE 6-13 Golgi Apparatus Golgi apparatus cis face (“receiving” side of Golgi apparatus) Vesicles also transport certain proteins back to ER Vesicles move from ER to Golgi Vesicles coalesce to form new cis Golgi cisternae 0.1 µm Cisternae Cisternal maturation: Golgi cisternae move in a cisto-trans direction PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Vesicles transport specific proteins backward to newer Golgi cisternae Lectures by Chris Romero Vesicles form and leave Golgi, carrying specific proteins to other locations or to the plasma membrane for secretion trans face (“shipping” side of Golgi apparatus) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings TEM of Golgi apparatus Lysosomes: Digestive Compartments • Membranous sac of hydrolytic enzymes • Hydrolyzes (breaks down) proteins, fats, polysaccharides, and nucleic acids • Recycle organelles and macromolecules (autophagy) • Hydrolyzes food taken up by the cell (phagocytosis) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Lysosomes: Digestive Compartments • Formation of lysosomes with hydrolytic enzyme Animation: Lysosome Formation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-14a 1 µm Nucleus Lysosome Lysosome contains active hydrolytic enzymes Food vacuole fuses with lysosome Hydrolytic enzymes digest food particles Digestive enzymes Plasma membrane PowerPoint Lectures for Lysosome Biology, Seventh Edition Neil Campbell and Jane Reece Food vacuole Lectures by Chris Romero Phagocytosis: lysosome digesting food Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Digestion Lysosome containing two damaged organelles LE 6-14b 1 µm Mitochondrion fragment Peroxisome fragment Hydrolytic enzymes digest organelle components Lysosome fuses with vesicle containing damaged organelle Lysosome PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Digestion Vesicle containing damaged mitochondrion Autophagy: Lectures by Chrislysosome Romerobreaking down damaged organelle Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Vacuoles: Diverse Maintenance Compartments • Vesicles and vacuoles (larger versions of vesicles) are membrane-bound sacs with varied functions • A plant cell or fungal cell may have one or several vacuoles Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Food vacuoles: form by phagocytosis • Contractile vacuoles: pump excess water out of cells (in many freshwater protists) • Central vacuoles (plant cells): hold organic compounds and water, maintain turgor pressure Video: Paramecium Vacuole Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-15 Central vacuole Cytosol Tonoplast Nucleus Central vacuole PowerPoint Lectures for Biology, Seventh Edition Cell wall Neil Campbell and Jane Reece Chloroplast Lectures by Chris Romero 5 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mitochondria and chloroplasts change energy from one form to another • Mitochondria are the sites of cellular respiration • Chloroplasts, found only in plants and algae, are the sites of photosynthesis • Mitochondria and chloroplasts are not part of the endomembrane system • Peroxisomes are oxidative organelles Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-17 Mitochondrion Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Inner membrane Cristae Matrix Mitochondrial Lectures by Chris Romero DNA Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 100 nm LE 6-18 Chloroplasts move with plant cells: cytoplasmic streaming video Chloroplast Ribosomes Stroma Chloroplast DNA Inner and outer membranes PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Thylakoid Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Granum 1 µm Peroxisomes: Oxidation • Specialized metabolic compartments bounded by a single membrane • Peroxisomes produce hydrogen peroxide and convert it to water How does the the cell protect itself from the toxic effects of hydrogen peroxide? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-19 Chloroplast Peroxisome Mitochondrion PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero 1 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Summary -Microscopy and differential centrifugation are two powerful methods to examine cellular structure and function. -Optimal size for most cells is generally low to optimize surface area:volume ratio. -All cells have plasma membrane, cytosol, DNA and ribosomes. -Prokaryotic cells tend to be smaller than eukaryotic, and lack nuclei, cytoplasmic membranes systems and organelles. -Eukaryotic cells have evolved or acquired many membrane bound compartments for specialized functions. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Please, ask questions. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotic Cell Structure: Part II Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Cytoskeleton -Intermediate Filaments -Microfilaments -Microtubules Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dynamic: shorten and lengthen Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-27b Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits Extending pseudopodium PowerPoint Lectures for Biology, Seventh Edition Speculate on the how actin causes movement? Neil Campbell and Jane Reece Amoeboid movement Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-26 Microvillus Intestinal cell Plasma membrane Function of MF? Microfilaments (actin filaments) Intermediate filaments Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 0.25 µm LE 6-27a Muscle cell Actin filament Myosin filament Myosin arm PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Myosin motors in muscle cell contraction Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-27c Nonmoving cytoplasm (gel) Chloroplast Streaming cytoplasm (sol) Vacuole Parallel actin filaments PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Cytoplasmic streaming in plant cells Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cell wall Dynamic: shorten and lengthen Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-21b Microtubule Vesicles PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 0.25 µm LE 6-21a Vesicle ATP Receptor for motor protein PowerPoint Lectures for Motor Biology, Seventh Edition protein (ATP powered) Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Microtubule of cytoskeleton LE 6-23a Motile sperm Direction of swimming Undulating movement flagellum PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Motion of flagella Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 5 µm LE 6-23b Direction of organism’s movement Direction of active stroke Direction of recovery stroke Motion of cilia for PowerPoint Lectures Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings protozoan 15 µm Microtubules: Power Flagella & Cilia Movement Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-25a Microtubule doublets ATPATP PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Dynein arm Molecular motor Dynein “walking” Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cross-linking LE 6-25b proteins inside outer doublets ATP Anchorage in cell Effect of cross-linking proteins PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Wavelike motion Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-24 MT organization in Flagella and Cilia 0.1 µm Outer microtubule doublet Dynein arms Central microtubule Cross-linking proteins inside outer doublets Microtubules Plasma membrane Basal body 9+2 0.5 µm PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Radial spoke Plasma membrane Basal body Microtubule-containing structure at base of flagellum and cilium Organization: Nine triplets In contrast: MT organization in cilia and flagella is?_____________ Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-24 Basal body anchors each flagellum and cilium 9 doublets+2 Plasma membrane Basal body 0.5 µm Basal Body Triplet PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Cross section of basal body Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nine triplets Centrioles • Occur in pairs oriented at right angle • Similar nine triplet organization as basal body • Present in animal cells • Contained in centrosome:microtubule organizing center (MTOC) • Note: plants cells have centrosomes but lack centrioles Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-22 Centrosome Microtubule Centrioles 0.25 µm PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Longitudinal section of one centriole Microtubules Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cross section of the other centriole Extracellular structures • Secreted materials on the outside surface of plasma membrane: – Cell walls (cellulose) of plants – Extracellular matrix (ECM) of animal cells – Intercellular junctions Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cell Walls of Plants Mixture of cellulose fibers plus other polysaccharides and protein • Distinctive to plants. Not present on animal cells • Protection against physical stress, predators and disease • Maintainance of cell shape • Prevention of excessive water uptake Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-28 Central vacuole of cell Plasma membrane Secondary cell wall Primary cell wall Central vacuole of cell Middle lamella 1 µm Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Extracellular Matrix (ECM) of Animal Cells • Proteoglycan complexes and other macromolecules • Functions: – Support – Adhesion to other cells or surfaces – Movement – Regulation (influences binding of hormones or other factors to receptors on plasma membrane) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-29a Collagen fiber EXTRACELLULAR FLUID Fibronectin Plasma membrane Integrin Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CYTOPLASM Microfilaments Proteoglycan complex LE 6-29b Proteoglycan complex Polysaccharide molecule Carbohydrates Core protein Proteoglycan molecule Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Intercellular Junctions • Between adjacent cells – Adhesion – Communication Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Plants: Plasmodesmata - Channels that perforate plant cell walls - Allow passage of water & small solutes between adjacent cells Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-30 Plasmodesmata Cell walls Interior of cell Interior of cell 0.5 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Plasma membranes Animals: Tight Junctions, Desmosomes, and Gap Junctions Tight junctions: on membranes of neighboring cells prevent leakage of extracellular fluid between cells Desmosomes (anchoring junctions): fasten cells together into strong sheets Gap junctions (communicating junctions) provide cytoplasmic channels between adjacent cells Animation: Tight Junctions Animation: Desmosomes Animation: Gap Junctions Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-31 Tight junctions prevent fluid from moving across a layer of cells Tight junction 0.5 µm Tight junction Intermediate filaments Desmosome 1 µm Space between cells Gap junctions Plasma membranes of adjacent cells Gap junction Extracellular matrix 0.1 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Cell: A Living Unit Greater Than the Sum of Its Parts • Cells rely on the integration of structures and organelles in order to function Think of the structures and organelles involved in the function of the following cell Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 6-32 5 µm Macrophage: patrols for & destroys foreign objects bacteria Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
