Section 19-1 CHAPTER Summary D. Growth and Reproduction 1. Binary Fission 2. Conjugation 3. Spore Formation E. Importance of Bacteria 1. Decomposers 2. Nitrogen Fixers 3. Human Uses of Bacteria • 19–1 Bacteria A. Classifying Prokaryotes 1. Eubacteria 2. Archaebacteria B. Identifying Prokaryotes 1. Shapes 2. Cell Walls 3. Movement C. Metabolic Diversity 1. Heterotrophs 2. Autotrophs 3. Releasing Energy
BACTERIA – Chapter 19 • How big are they? • What are their structures? • How do they eat and make energy? • How do they reproduce? • In general, what role do many bacteria play? (“niche”) • What are some of the positive uses of bacteria?
Eubacteria Archaebacteria Living in soil Infecting large organisms Thick mud Animal digestive tracts Salty lakes Hot springs Concept Map Section 19-1 Bacteria are classified into the kingdoms of include a variety of lifestyles such as live in harsh environments such as
Eubacteria: Prokaryotic More species Found everywhere Cell walls of peptidoglycan Archeabacteria: Prokaryotic No peptidoglycan Different lipids in its membrane Found in harsh environments DNA sequences similar to eukaryotes
The domain Archaea • Include prokaryotes that do not have peptidoglycan walls • 3 major groups: Methanogens Extreme halophiles Extreme thermophiles
Methanogens • Methanogens: convert hydrogen and carbon dioxide into methane to generate energy anaerobically. Methanogens are obligate anaerobes: they are killed by oxygen. • Methanogens digest cellulose in cow and termite guts. Each cow belches 50 liters of methane a day. A major greenhouse gas. • Methanogens are also in swamps, wetlands, and garbage dumps. (Garfield Shopping Mall)
Halophiles • Extreme halophiles. Grow in very salty conditions. Colorful bacteria in seawater evaporation beds, Great Salt Lake. • Mostly aerobic metabolism. • Some have a form of photosynthesis that uses bacteriorhodopsin, a pigment very similar to the rhodopsin pigment in our eyes. It is also called “purple membrane protein”
Thermophiles • Extreme thermophiles. Live at very high temperatures: ocean hydrothermal vents (up to 113o C, which would be boiling except for the high pressure under the ocean), hot springs in Yellowstone National Park. • Use sulfur to generate energy just like we use oxygen: donate electrons to sulfur to create hydrogen sulfide. Some generate sulfuric acid instead—they live at very low pHs.
Methods for Identifying and classifying microorganisms * Morphological characteristics * Differential staining * Biochemical tests • Bergey’s Manual of Systematic Bacteriology-Used to identify microorganisms based on the results of these observations. The “bible” of bacterial identification.
Basic BacterialShapes • Three basic shapes: • Coccus • Bacillus • Spirilum • Common Prefixes: • Diplo - two • Tetra - four • Staphylo - cluster • Strepto - chain
Bacterial morphologies (1) Assorted Shapes
Appendages - flagella, pili • Surface layers - capsule, cell wall, cell membrane • Cytoplasm - nuclear material, ribosome, cytoplasm • Specialized structure - endospore
Examples of bacterial flagella arrangement schemes. • A-Monotrichous; B-Lophotrichous; • C-Amphitrichous; D-Peritrichous;
Bacterial Cell Wall • Gram (+) Those made up of peptidoglycan. (Appear blue/purple after staining) • Gram (-) Those with little petidoglycan but a great deal of lipopolysaccharide. (Appear pink/red after staining)
Gram Stain (-) ( - ) (+)
Capsule or slime layer • Many bacteria are able to secrete material that adheres to the bacterial cell • It consists of polysaccharide (andsometimes polypeptide) on bacilli. Most of them have only polysaccharide. It is a protective layer that resists host phagocytosis (process of engulfing).
How do bacteria “breathe”?- Obligate aerobe- Obligate anaerobe- Facultative anaerobes
Endotoxin VS Exotoxin • Exotoxins: Produced inside the bacterium and given off. • Endotoxins: Make up the bacterium’s cell wall (some lipopolysaccharides in Gram (-))
Cytoplasm & Structures 80% water, nucleic acids, proteins, carbohydrates, lipid and inorganic ions etc. 1. Bacterial chromosomes Single large circular double stranded DNA (no histone proteins) 2. Plasmids An extra loop of DNA found in some bacteria. Used in genetic engineering.
Cytoplasm & Structures (cont’d) 3. Ribosome Site of protein synthesis. (Amino acids linked together)
Bacterial Reproduction • Binary fission (What is it?) • Conjugation (What does it accomplish?) • Endospores (What is their advantage?)
Two different stains showing endospores. Closteridium tetani on the right.
Growth of Bacteria • Under ideal conditions, bacteria grow very rapidly: some double in number every 20 minutes. • Doubling in number: 1-2-4-8-16-… is exponential growth. It starts off slowly, but once going the number of bacteria increase very rapidly • Usually some nutrient runs short, or waste material builds up, and growth ceases. Eventually a die-off occurs, reducing the number of live bacteria.
“Ideal conditions?” • Temperature • Food • Water • No light (or light?) • Oxygen (or no oxygen)
Section Outline Section 19-2 19–2 Viruses A. What Is a Virus? B. Viral Infection 1. Lytic Infection 2. Lysogenic Infection C. Retroviruses D. Viruses and Living Cells
BioEd Online Viruses—Size • Here is how you can imagine the size of viruses: “If a virus was the size of a basketball…” • A bacterium would be as large as a city block • A grain of sand would be two miles long • A person would be 4,000 miles tall
RNA DNA Head RNA Capsid Capsid proteins Tail sheath Tail fiber Surface proteins Membrane envelope Figure 19-9 Virus Structures Tobacco Mosaic Virus Influenza Virus T4 Bacteriophage
Envelope Nucleic acid Capsid What Are Viruses Made Of? • Viruses are composed of nucleic acid, proteins, and sometimes, lipids. • *Nucleic acid, which can be either DNA or RNA, encodes the genetic information to make virus copies. • *The nucleic acid is surrounded by a protective protein coat, called a capsid. • *An outer membranous layer, called an envelope, made of lipid and protein, surrounds the capsid in some viruses..
Lysogenic into the Lytic Cycle