Presentation on theme: "Functional Anatomy of Prokaryotic and Eukaryotic Cells"— Presentation transcript:
1Functional Anatomy of Prokaryotic and Eukaryotic Cells Chapter 4Functional Anatomy of Prokaryotic and Eukaryotic Cells
2Q&APenicillin was called a “miracle drug” because it doesn’t harm human cells. Why doesn’t it?
3Prokaryotic and Eukaryotic Cells Learning Objective4-1 Compare and contrast the overall cell structure of prokaryotes and eukaryotes.
4Prokaryotic and Eukaryotic Cells Prokaryote comes from the Greek words for prenucleus.Eukaryote comes from the Greek words for true nucleus.
5Prokaryote Eukaryote One circular chromosome, not in a membrane No histonesNo organellesPeptidoglycan cell walls if BacteriaPseudomurein cell walls if ArchaeaBinary fissionPaired chromosomes, in nuclear membraneHistonesOrganellesPolysaccharide cell wallsMitotic spindle
6Check Your Understanding What is the main feature that distinguishes prokaryotes from eukaryotes? 4-1
7The Prokaryotic Cell Learning Objective 4-2 Identify the three basic shapes of bacteria.
8Prokaryotic Cells: Shapes Average size: 0.2 –1.0 µm 2 – 8 µmMost bacteria are monomorphicA few are pleomorphicFigure 4.7a
23Axial Filaments Also called endoflagella In spirochetes Anchored at one end of a cellRotation causes cell to moveFigure 4.10a
24A Diagram of Axial Filaments ANIMATION SpirochetesFigure 4.10b
25Fimbriae and PiliFimbriae allow attachmentFigure 4.11
26Fimbriae and PiliPiliFacilitate transfer of DNA from one cell to anotherGliding motilityTwitching motility
27Check Your Understanding Why are bacterial capsules medically important? 4-3How do bacteria move? 4-4
28The Cell Wall Learning Objectives 4-5 Compare and contrast the cell walls of gram-positive bacteria, gram-negative bacteria, acid-fast bacteria, archaea, and mycoplasmas.4-6 Compare and contrast archaea and mycoplasmas.4-7 Differentiate protoplast, spheroplast, and L form.
29The Cell Wall Prevents osmotic lysis Made of peptidoglycan (in bacteria)Figure 4.6
30Peptidoglycan Polymer of disaccharide: N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM)Figure 4.12
31Peptidoglycan in Gram-Positive Bacteria Linked by polypeptidesFigure 4.13a
35Gram-Positive Cell Walls Teichoic acidsLipoteichoic acid links to plasma membraneWall teichoic acid links to peptidoglycanMay regulate movement of cationsPolysaccharides provide antigenic variationFigure 4.13b
37Gram-Negative Outer Membrane Lipopolysaccharides, lipoproteins, phospholipidsForms the periplasm between the outer membrane and the plasma membraneFigure 4.13c
38Gram-Negative Outer Membrane Protection from phagocytes, complement, and antibioticsO polysaccharide antigen, e.g., E. coli O157:H7Lipid A is an endotoxinPorins (proteins) form channels through membrane
40The Gram Stain Mechanism Crystal violet-iodine crystals form in cellGram-positiveAlcohol dehydrates peptidoglycanCV-I crystals do not leaveGram-negativeAlcohol dissolves outer membrane and leaves holes in peptidoglycanCV-I washes out
42Atypical Cell Walls Acid-fast cell walls Like gram-positive Waxy lipid (mycolic acid) bound to peptidoglycanMycobacteriumNocardiaFigure 24.8
43Atypical Cell Walls Mycoplasmas Archaea Lack cell walls Sterols in plasma membraneArchaeaWall-less orWalls of pseudomurein (lack NAM and D-amino acids)
44Damage to the Cell Wall Lysozyme digests disaccharide in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycanProtoplast is a wall-less cellSpheroplast is a wall-less gram-positive cellProtoplasts and spheroplasts are susceptible to osmotic lysisL forms are wall-less cells that swell into irregular shapes
45Check Your Understanding Why are drugs that target cell wall synthesis useful? 4-5Why are mycoplasmas resistant to antibiotics that interfere with cell wall synthesis? 4-6How do protoplasts differ from L forms? 4-7
46Structures Internal to the Cell Wall Learning Objectives4-8 Describe the structure, chemistry, and functions of the prokaryotic plasma membrane.4-9 Define simple diffusion, facilitated diffusion, osmosis, active transport, and group translocation.4-10 Identify the functions of the nucleoid and ribosomes.4-11 Identify the functions of four inclusions.4-12 Describe the functions of endospores, sporulation, and endospore germination.
52The Plasma MembraneDamage to the membrane by alcohols, quaternary ammonium (detergents), and polymyxin antibiotics causes leakage of cell contentsANIMATION Membrane PermeabilityANIMATION Membrane Structure
53Movement of Materials across Membranes Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentrationFigure 4.17a
54Movement of Materials across Membranes Facilitated diffusion: Solute combines with a transporter protein in the membraneFigure 4.17b-c
55Movement of Materials across Membranes ANIMATION Passive Transport: Principles of DiffusionANIMATION Passive Transport: Special Types of Diffusion
56Movement of Materials across Membranes Osmosis: The movement of water across a selectively permeable membrane from an area of high water to an area of lower water concentrationOsmotic pressure: The pressure needed to stop the movement of water across the membraneFigure 4.18a
57Movement of Materials across Membranes Through lipid layerAquaporins (water channels)Figure 4.17d
60Movement of Materials across Membranes Active transport: Requires a transporter protein and ATPGroup translocation: Requires a transporter protein and PEPANIMATION Active Transport: OverviewANIMATION Active Transport: Types
61Check Your Understanding Which agents can cause injury to the bacterial plasma membrane? 4-8How are simple diffusion and facilitated diffusion similar? How are they different? 4-9
62CytoplasmThe substance inside the plasma membraneFigure 4.6
84CytoplasmCytoplasm membrane: Substance inside plasma and outside nucleusCytosol: Fluid portion of cytoplasmCytoskeleton: Microfilaments, intermediate filaments, microtubulesCytoplasmic streaming: Movement of cytoplasm throughout cells
85Ribosomes Learning Objective 4-17 Compare the structure and function of eukaryotic and prokaryotic ribosomes.
86Ribosomes Protein synthesis 80S 70S Membrane-bound: Attached to ER Free: In cytoplasm70SIn chloroplasts and mitochondria
87Check Your Understanding Identify at least one significant difference between eukaryotic and prokaryotic flagella and cilia, cell walls, plasma membranes, and cytoplasm.4-13–4-16The antibiotic erythromycin binds with the 50S portion of a ribosome. What effect does this have on a prokaryotic cell? On a eukaryotic cell? 4-17
88Organelles 4-18 Define organelle. 4-19 Describe the functions of the nucleus, endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, mitochondria, chloroplasts, peroxisomes, and centrosomes.
89Organelles Nucleus: Contains chromosomes ER: Transport network Golgi complex: Membrane formation and secretionLysosome: Digestive enzymesVacuole: Brings food into cells and provides support
90Organelles Mitochondrion: Cellular respiration Chloroplast: PhotosynthesisPeroxisome: Oxidation of fatty acids; destroys H2O2Centrosome: Consists of protein fibers and centrioles