Cell Biology Outline - Cells Cell Theory Cell Size Microscopes Prokaryotic Cells Eukaryotic Cells Cell Membranes 2 Cell Theory 1665 - Robert Hooke Describes small rooms in tree bark 1838-39 Matt Schleiden & Ted Schann All organisms are composed of one or more cells. Cells are the smallest living units of all living organisms. Late 1800 s Rudolf Virchow s contribution Cells arise only by division of a previously existing cell. Life on earth represents a continuous line of descent Cell Theory Cell Theory 1. All organisms are composed of cells. 2. Cells are the smallest living things. 3. Cells arise only from pre-existing cells. All cells today represent a continuous line of descent from the first living cells. 3 4 1
Why Are Cells Small? Cell size Small cells have an optimum surface area to volume ratio Surface area to volume ratio 3:1 0.3:1 5 Light microscopes resolve structures 200nm apart. Electron microscopes resolve structures 0.2nm apart. 6 Microscope Properties Magnification enlarge objects Resolution - minimum distance two points can be distinguished as separate points Light Microscopy Compound Light Microscope Phase Contrast Microscope 67 µm Light microscopes Electron microscopes Transmission (TEM) Scanning (SEM) Scanning Tunneling (STEM) Dark-field Microscope Fluorescence Confocal Microscope 7 8 2
Views through a microscope - Euglena Light microscope Transmission Electron Microscope Electron Microscopy Scanning Electron Microscope LM 1,000 Scanning Electron Microscope TEM 2,800 SEM TEM 67 µm Light micrograph SEM 2,000 9 Transmission Electron Microscope Image of 1 Cilium 10 Scanning Tunneling Electron Microscopy Cell Structure All cells have certain structures in common. 1. genetic material in a nucleoid or nucleus 2. cytoplasm a semifluid matrix 3. plasma membrane a phospholipid bilayer Corral of iron atoms on a copper surface 2 nm DNA 11 12 3
Types of Cells Prokaryotic Cell Structure 1. Prokaryotic Bacteria Archaebacteria 2. Eukaryotic Plants Animals Fungi Protists 13 Copyright 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Bacterial Cell Walls Cell walls give bacteria different shapes Gram Positive Rods Spheres Gram Negative Spirillum 15 16 4
Prokaryotic Cells Simplest organisms all bacteria Plasma Membrane barrier & regulates Characterized by compartmentalization Eukaryotic Cell Structure Nucleus Nucleus Inside the Plasma Membrane Cytoplasm Ribosomes DNA Outside the Plasma Membrane Cell wall Peptidoglycan layer(s) gram-positive or gram-negative Capsule Polysaccharide: Adhesion & Hydration Pili - cell adhesion or DNA transfer 17 Nucleus Plasma Membrane Cytoplasm Cytoplasm Cytoplasm Plasma Membrane Plasma Membrane 18 Eukaryotic Cell Structure Nucleus Nucleus Nuclear pores 19 Nucleus 1. Repository of genetic information 2. Synthesis of RNA for ribosome construction for protein synthesis Copyright 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5
Ribosomes Fig. 4.11 Ribosomes and Endoplasmic Reticulum Ribosomes RNA-protein complexes composed of two subunits Site of protein synthesis Assembled in nucleoli Rough endoplasmic reticulum Rough endoplasmic reticulum Smooth endoplasmic reticulum 21 Endoplasmic Reticulum Forms compartments Large surface area for metabolism Rough ER Protein synthesis by ribosomes Transport Smooth ER Lipid synthesis Detoxification Golgi viewed with fluorescence microscopy Golgi Apparatus 23 24 6
Golgi Apparatus Endomembrane System Collect, package, and distribute molecules Outgoing Secretory Vesicles Incoming Transport Vesicles 25 26 Lysosomes Endomembrane System & Lysosomes Lysosomes - membrane-bound digestive vesicles Lysosome Movie Plasma membrane Rough ER 1 Transport vesicle Golgi apparatus 2 Lysosomes Food Engulfment of particle 3 Food vacuole 4 Digestion 5 27 Copyright 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 7
Mitochondrion Mitochondrion Exterior and interior membranes Semi-autonomous DNA Ribosomes Function: ATP synthesis aerobic respiration 29 30 Amoeboid Movement Cytoskeleton Cilia and Flagella Flagellum SEM 4,100 Plasma membrane TEM 206,500 TEM 206,500 http://www.iknow.net/cdroms/cell_ cdrom/cellmovies.shtml http://www.exploratorium.edu/imaging_station/gallery.php?as set=elodea&category=cellstructure&type=hbvideo 31 LM 600 Basal body 32 8
Protein Fibers of the cytoskeleton Network of protein fibers supporting cell shape, movement and anchoring organelles Actin and Microfilaments Actin Microfilaments Actin subunit 7 nm Fibrous subunits 10 nm Tubulin subunit 25 nm Microfilament Intermediate filament Microtubule Copyright 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Microtubules Intermediate Filaments Intermediate Filaments Rat epithelial cell Keratins: Hair & Nails Red blood cells 9
Cytoskeleton - Summary Network of protein fibers Shape Movement anchoring organelles Microfilaments - made of Actin protein Cell shape & movement Microtubules - made of tubulin protein Organelle & chromosome movement Intermediate filaments fibrous protein Structural stability Eukaryotic Cell Structure Golgi apparatus Actin filament Cytoskeleton Microtubule Intermediate filament Smooth endoplasmic reticulum Nuclear envelope Nucleolus Nucleus Microvilli Plasma membrane Centriole Peroxisome Lysosome Ribosomes Mitochondrion Rough endoplasmic reticulum Cytoplasm Central vacuole Plant Cell Plant Cell Walls Plasmodesmata Chloroplast Cell wall Plasma membrane 10
Plant Cells - Vacuole Plant Cells Chloroplasts Chloroplast structure Two external membranes Internal membranes DNA Ribosomes Function: Photosynthesis Plant Cell Unique Characteristics Central vacuole Large compartments in mature plant cells, Storage facility for water & other materials Produce turgor (pressure) for cell rigidity End Cells Cell wall Cellulose & other polysaccharides Support of Cells, Tissues, Organs, Whole Plant Chloroplasts Membranes: 2 in envelope & many internal Semiautonomous: DNA & ribosomes Photosynthesis 11