Chapter 5 Microbiology Basics

1. Chapter 5Microbiology Basics

2. Introduction • The human body is often invaded by disease-producing organisms; these pathogens disrupt normal structure and function and are a common cause of disability and death.

3. Disease and Pathogens • Disease is a failure of the body to function normally. • Infections are diseases caused by pathogens.

4. Types of Pathogens • Microorganisms • Bacteria (cocci, bacilli, curved rods, chlamydiae, rickettsiae) • Viruses • Fungi • Protozoa (amebas, ciliates, flagellates, sporozoa) • Other Larger Pathogens • Worms • Arthropods

5. Laboratory Identification • Staining • Gram stain • Acid-fast stain • Culture

6. Spread of Infection • Portals of Entry • Most pathogens enter the body through the respiratory tract and the gastrointestinal tract. • Portals of Exit • The most common portals of exit are the respiratory and gastrointestinal tracts. • Modes of Transmission • Person to person • Environment to person • Tiny animals to person

7. Six Germ-Laden Stories • Wash Those Mitts • Flora and Her Vaginal Itch • Rick, Nick, and the Sick Tick • Why Typhoid Mary Needed to Lose Her Gallbladder • Pox News Alert! • The Chief of Staph Reports

8. Introduction • To carry on its functions, the cell must metabolize its fuel: the carbohydrates, proteins, and fats.

9. Metabolism • Anabolism: includes the chemical reactions that build larger, more complex substances from simpler substances. • Catabolism: includes those chemical reactions that break down larger, more complex substances into simpler substances.

10. Carbohydrates: Structure and Function • Carbohydrates: composed of monosaccharides, disaccharides, and polysaccharides. • Glucose is the primary source of energy. • Glucose can be stored as glycogen, and converted to and stored as fat. • Glucose can be catabolized anaerobically and aerobically. Anaerobically, glucose is incompletely broken down (glycolysis) into lactic acid and small amounts of ATP. Aerobically, glucose is broken down completely (citric acid cycle) into carbon dioxide (CO2) and water (H2O) and large amounts of energy (ATP). • Glucose can be synthesized from nonglucose substances such as protein (gluconeogenesis).

11. Lipids • The most common lipids are triglycerides, phospholipids, and steroids. • Lipids are used primarily in the synthesis of membranes. • The long chains of fatty acids are broken down into two-carbon units and metabolized by the enzymes of the citric acid (Krebs) cycle into CO2 and H2O, releasing large amounts of energy.

12. Protein • Protein is composed of a series of amino acids linked together by peptide bonds in a specific sequence. • Proteins are used primarily in the synthesis of hormones, enzymes, antibodies, plasma proteins, muscle proteins, hemoglobin, and cell membranes. Proteins are also used as fuel and as raw material for making glucose (gluconeogenesis). • There is special handling of protein nitrogen by the urea cycle.

13. Protein Synthesis and DNA • DNA (deoxyribonucleic acid) • DNA stores the code for protein synthesis. • DNA is a double-stranded series of nucleotides, arranged in a twisted-ladder formation. • A nucleotide is composed of a sugar, a phosphate group, and a base. For DNA, the sugar is deoxyribose, and the bases are adenine, thymine, cytosine, and guanine. • The genetic code is stored in a sequence of three bases.

14. Protein Synthesis and DNA - cont’d • RNA • The structure of ribonucleic acid (RNA) is similar to the structure of DNA, with the following differences: in RNA the sugar is ribose; RNA is single-stranded; and the RNA bases are adenine, uracil, cytosine, and guanine. • Two types of RNA include messenger RNA (mRNA) and transfer RNA (tRNA). • Protein Synthesis: five steps summarized in Figure 4-9.