A Tour of the Cell Chapter 4. Outline. Early contributors to Understanding Cells. Cell Theory. Cell Size s Matt Schleiden & Ted Schann

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1 A Tour of the Cell Chapter 4 Outline History of the science behind cells Cell theory & its importance Why are cells small? Microscopes Cell structure and function Prokaryotic cells Eukaryotic cells Early contributors to Understanding Cells Anton van Leeuwenhoek (late 1600 s) Described animalcules Robert Hooke 1665 Light microscope Views and first describes cells Cell Theory Cell Size 1800 s Matt Schleiden & Ted Schann All organisms are composed of one or more cells. Cells are the smallest living units of all living organisms. Rudolf Virchow added to the Cell Theory Cells arise only by division of a previously existing cell. Life on earth represents a continuous line of descent Most plant and animal cells Most bacterial cells 1

2 Effect of Cell Size on Surface Area Surface area to volume ratio 0.3:1 3:1 Visualizing Cells Resolution - minimum distance two points can be apart & still distinguished as separate points Microscopes Increase Resolution Magnify Types of Microscopes Light microscopes Electron Microscopes Types Microscopes of Microscopes Light Micrograph of Euglena Transmission Electron Microscope Light Microscope Scanning Electron Microscope LM 1,000 Scanning Electron Micrograph of Euglena Transmission Electron Micrograph of Euglena SEM 2,000 TEM 2,800 2

3 Comparison of Light & Electron Microscopy Light Light Fluorescence Confocal Microscopy Cancer Cells SEM SEM TEM TEM Scanning Tunneling Electron Microscopy Cell Organization Types of cell organization Prokaryotic Bacteria Corral of iron atoms on a copper surface 2 nm DNA Eukaryotic Plants, animals, fungi & protists Prokaryotic & Eukaryotic Cell Comparison Compared to eukaryotic cells, prokaryotic cells are 1) smaller 2) structurally simpler Prokaryotic cell Eukaryotic cell Capsule/Sheath Cell wall A Prokaryotic cell Prokaryotic flagella Nucleoid region (DNA) Organelles Pili 3

4 A Cell Wall gives bacteria different shapes Eukaryotic Cells Rods Spheres Common characteristics Cytoplasm Membrane Cytoplasm Spirals 3. Membranes Form compartments Separate metabolic activity Increase surface area An animal cell Smooth endoplasmic Rough reticulum endoplasmic reticulum Flagellum Lysosome Centriole Peroxisome Microtubule Intermediate Cytoskeleton filament Microfilament Golgi apparatus Mitochondrion The nucleus Chromatin Nucleolus Pore Nuclear Envelope Functions- 1. Control center 2. Stores genetic information 3. Assemble ribosomes on nucleolus Figure 4.7 Smooth and rough endoplasmic reticulum Smooth ER Smooth ER Functions 1. Synthesis 2. Forms compartments 3. Enormous surface area Nuclear envelope TEM 45,000 4

5 Packaging a protein by the rough ER Golgi apparatus Functions 1. Packages products of synthesis 2. Vesicles deliver products Transport vesicle 4 Ribosome Glycoprotein inside transport vesicle Transport vesicle from ER Golgi apparatus 1 3 Sugar chain New vesicle forming Polypeptide 2 Glycoprotein Shipping side of Golgi apparatus Transport vesicle from the Golgi TEM 130,000 Lysosome formation and functions 1 Transport vesicle Golgi apparatus Lysosomes in Development 2 Lysosomes Food Engulfment of particle 3 Food vacuole 4 Digestion 5 Organelles of the Endo System Nuclear envelope Transport vesicle Transport vesicle The mitochondrion Mitochondrion Golgi apparatus Lysosome Transport vesicle Inter space Movie dsu.edu/tfrey/ MitoMovie.htm Outer Matrix Inner Cristae Mitochondrion Smooth ER TEM 44,880 5

6 Mitochondrion Exterior and interior s Amoeboid Movement Cytoskeleton Semi-autonomous DNA Function: ATP synthesis Energy Metabolism Aerobic respiration cdrom/cellmovies.shtml set=elodea&category=cellstructure&type=hbvideo Cilia and Flagella Flagellum Protein Fibers of the cytoskeleton Network of protein fibers supporting cell shape, movement and anchoring organelles SEM 4,100 TEM 206,500 TEM 206,500 Actin subunit 7 nm Fibrous subunits 10 nm Tubulin subunit 25 nm LM 600 Basal body Microfilament Intermediate filament Microtubule Intermediate Filaments Actin and Microfilaments Intermediate Filaments Rat epithelial cell Actin Microfilaments Keratins: Hair & Nails Red blood cells 6

7 Microtubules Cytoskeleton - Summary Network of protein fibers Shape Movement anchoring organelles Microfilaments - made of Actin protein Cell shape & movement Intermediate filaments fibrous protein Structural stability Microtubules - made of tubulin protein Organelle & chromosome movement Figure 4.4A An animal cell Figure 4.4B A plant cell Smooth endoplasmic reticulum Rough endoplasmic reticulum Central vacuole Flagellum Lysosome Chloroplast Cytoskeleton Microtubule Intermediate filament Microfilament Golgi apparatus Mitochondrion Cell wall Plant Cell Walls Plant Cells - Vacuole Plasmodesmata 7

8 Plant Cells Chloroplasts Chloroplast structure Two external s Internal s DNA Function: Photosynthesis Plant Cells Chloroplasts Membranes, DNA & Photosynthesis Central vacuole 1 filled with Water & other materials Storage & Turgor pressure Cell wall Cellulose & other polysaccharides Support cells END Tour of the Cell 8