Microbiology AN INTRODUCTION EIGHTH EDITION TORTORA FUNKE CASE Dr. Fadilah Sfouq Female department 2015

What is a Microbe? What is microbiology? Smaller than 0.1mm and are usually too small to be seen with the unaided eye –Includes bugs, germs, viruses, protozoan, bacteria. The branch of biology dealing with the structure, function, uses, and modes of existence of microscopic organisms

Why study Microbiology Microbes are related to all life. –In all environments –Many beneficial aspects –Related to life processes (food web, nutrient cycling) –Only a minority are pathogenic. –Most of our problems are caused by microbes

Chapter 4, part A Functional Anatomy of Prokaryotic and Eukaryotic Cells

Objectives Compare and contrast the overall cell structure of prokaryotes and eukaryotes. Identify the three basic shapes of bacteria. Describe structure and function of the glycocalyx, flagella, axial filaments, fimbriae, and pili. Compare and contrast the cell walls of gram-positive bacteria, gram-negative bacteria, acid-fast bacteria, and mycoplasmas. Describe the structure, chemistry, and functions of the prokaryotic plasma membrane. Identify the functions of the nuclear area, ribosomes, and inclusions. Describe the functions of endospores, sporulation, and endospore germination. What you should remember from Biochemistry: Define organelle. Describe the functions of the nucleus, endoplasmic reticulum, ribosomes, Golgi complex, lysosomes, vacuoles, mitochondria, chloroplasts, peroxisomes. Explain endosymbiotic theory of eukaryotic evolution.

Three Domain Classification Bacteria Archaea Eukarya –Protista –Fungi –Plants –Animals

Types of Microorganisms Bacteria Archaea Fungi Protozoa Algae Viruses Multicellular animal parasites Prions

Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells –Prokaryote comes from the Greek words for prenucleus. –Eukaryote comes from the Greek words for true nucleus.

Comparing Prokaryotic and Eukaryotic Cells Common features:  DNA and chromosomes  Cell membrane  Cytosol and Ribosomes Distinctive features: ?

One circular chromosome, not in a membrane No histones No organelles Peptidoglycan cell walls Binary fission Prokaryote Eukaryote Paired chromosomes, in nuclear membrane Histones Organelles Polysaccharide cell walls Mitotic spindle

Average size: µm  µm Basic shapes:

Unusual shapes –Star-shaped Stella –Square Haloarcula Most bacteria are monomorphic A few are pleomorphic

Pairs: diplococci, diplobacilli Clusters: staphylococci Chains: streptococci, streptobacilli Arrangements

Outside cell wall Usually sticky A capsule is neatly organized A slime layer is unorganized & loose Extracellular polysaccharide allows cell to attach Capsules prevent phagocytosis Glycocalyx

Outside cell wall Made of chains of flagellin Attached to a protein hook Anchored to the wall and membrane by the basal body Flagella

Flagella Arrangement

Fimbriae allow attachment to surfaces Pili are used to transfer DNA from one cell to another

Motility Due to rotation of flagella Mechanism of rotation: “Run and tumble” Move toward or away from stimuli (taxis)

Prevents osmotic lysis Made of peptidoglycan (in bacteria) Cell Wall

Polymer of disaccharide N-acetylglucosamine (NAG) & N- acetylmuramic acid (NAM) Linked by polypeptides Peptidoglycan

Gram + Cell Wall Thick layer of peptidoglycan teichoic acid on surface Thin peptidoglycan No teichoic acids Outer membrane –LPS –O - polysaccaride –Lipid A Gram – Cell Wall

Teichoic acids: –Lipoteichoic acid links to plasma membrane –Wall teichoic acid links to peptidoglycan May regulate movement of cations Polysaccharides provide antigenic variation Gram-Positive cell walls

Lipopolysaccharides, lipoproteins, phospholipids. Forms the periplasm between the outer membrane and the plasma membrane. Protection from phagocytes, complement, antibiotics. O polysaccharide antigen, e.g., E. coli O157:H7. Lipid A is an endotoxin. Porins (proteins) form channels through membrane Gram-Negative Outer Membrane

Figure 4.13c

Crystal violet-iodine crystals form in cell Gram-positive –Alcohol dehydrates peptidoglycan –CV-I crystals do not leave Gram-negative –Alcohol dissolves outer membrane and leaves holes in peptidoglycan –CV-I washes out Gram Stain Mechanism

Mycoplasmas –Lack cell walls –Sterols in plasma membrane Archaea –Wall-less, or –Walls of pseudomurein (lack NAM and D amino acids) Atypical Cell Walls

Lysozyme digests disaccharide in peptidoglycan. Penicillin inhibits peptide bridges in peptidoglycan. Protoplast is a wall-less cell. Spheroplast is a wall-less Gram-positive cell. L forms are wall-less cells that swell into irregular shapes. Protoplasts and spheroplasts are susceptible to osmotic lysis. Damage to Cell Walls

Plasma Membrane Figure 4.14a

Plasma Membrane Phospholipid bilayer Peripheral proteins Integral proteins Transmembrane proteins Figure 4.14b

Membrane is as viscous as olive oil. Proteins move to function Phospholipids rotate and move laterally Fluid Mosaic Model Figure 4.14b