Chapter 10 Key Terms Bacteria Binary Fission Conjugation Transformation Parasitic Virus Bacteriophage Retrovirus Vaccination Pathogen Inflammation Antibody Antibiotic Coccus

Bacteria and Viruses: Microbiology Part I Biology Chapter 10 Bacteria and Viruses: Microbiology Part I

Classification Kingdom Phylum Class Order Family Genus Species The scientific name includes the genus and species of that organism Genus is capitalized, species is lowercase Both are underlined or italicized Ex. Canis familiaris

Bacteria All the organisms found in the Kingdoms Archaebacteria and Eubacteria Importance Pathogenic Decomposers Make antibiotics Help in production of food Yogurt, cheese, pickles…

Kingdom Archaebacteria Organisms that live in extreme environments Extreme Thermophiles Live in very hot or cold environments (hot springs) Extreme Halophiles Live in very salty environments (dead sea) Methanogens Live in anaerobic environments such as swamps, sewage, intestines Produce methane gas

Kingdom Eubacteria Larger of the two kingdoms Bacteria we typically think of Live in many different conditions and are often classified by shape or by their “Gram’s stain” Shape Coccus Bacillus Spirillum

Bacteria Structure of bacterial cells Cell membrane is phospholipid bilayer Most have cell wall that contains peptidoglycan Gram’s stain shows the amount of peptidoglycan in the cell wall Slimy capsule surrounds the cell All are prokaryotic cells No membrane around the nucleus (“cytoplasmic structure”) Single chromosome appears in the nucleoid region Flagella

Bacteria Reproduction Bacteria reproduce by binary fission A type of asexual reproduction Reproduce at an average of every 30 minutes Optimal conditions: Moisture Temperature Food Volume-surface area ratio

Structure of Viruses 2 main parts Some have a sheath like envelope Core: Either DNA or RNA (not both) Capsid: Protein covering Some have a sheath like envelope All viruses are dead without a host Use organelles and enzymes from the host organism

Viruses Virulence Lytic Cycle Ability of a pathogen to affect a cell Attachment Entry Replication and transcription Assembly Release

Viruses Lysogenic Cycle Latent cell (inactive) Virus incorporates its genome into the genome of the host organism’s cells Host cell replicates itself AND virus Stimulus causes virus to become virulent

Viruses Other types of viruses Persistent Infections Host cell slowly releases virus particles Does not destroy cell Transforming Viruses Add new genetic information Changes function of cell – no longer productive (warts)

Viral diseases Most often only affect 1 type of organism, and even 1 type of cell within the organism Rabies and polio attack nervous system Smallpox and chicken pox attack skin cells Some viruses release toxins into the blood that can affect other parts of the body Influenza virus affects respiratory system, but we sometimes get headaches, muscle soreness, nausea…

Viral Diseases Controlling Viral Diseases Vaccination programs Purpose: activate immune system to recognize and respond to virus or other organism and prevent disease Vaccination types: Inactivated: virus is altered so it cannot replicate in host cell Attenuated: “live” virus, but is not virulent

Viral Diseases Antiviral Drugs Interferons: chemicals released by infected cells to inhibit viral replication Used today, but our knowledge and their effectiveness is still limited

Diseases and Disorders Infectious Diseases Ailments that are caused by viruses or organisms Pathogens The agent that invades the body and causes the disease Ex. bacteria, viruses, worms… How they cause disease Tissue destruction Toxin formation

Diseases and Disorders Contagious (communicable disease) A disease that can spread from one person to another

How Diseases Spread Airborne infections Direct contact infections Transmitted by pathogens suspended in water droplets in the air Direct contact infections Transmitted by direct contact with sore on skin or mucous membrane of infected person Indirect contact infections Touching an object after someone who is infected

How Diseases Spread Contamination infections Wound infections Pathogens enter body by contaminated food or water Wound infections Pathogens that enter body through wounds Vector-carried infections Transmitted by insects Immune carriers Transmitted by individuals immune to disease

Body Defenses Structural defenses Skin Mucous membranes Tears Effective at keeping pathogens out of the body Mucous membranes Nasal passages, trachea, lungs Tears Protect eye by keeping it moist Contains Lysozyme – attacks bacterial cell walls

Body Defenses Nonspecific Defenses Inflammation Lymphatic system Fever Chemicals released from cells cause blood vessels to dilate, causing the area to swell Histamine: chemical released by cells Lymphatic system Filters pathogens and toxins from blood Fever Increased temperature to kill microorganisms

Body Defenses Specific Defenses Antibodies Special cells Chemicals that circulate in the blood to fight specific pathogens Special cells Such as leukocytes, phagocytes

Fighting Disease Antibiotics How they work Chemicals to combat infectious bacterial diseases Can now be made synthetically How they work Inhibit growth of bacteria/pathogen Destroys bacteria/pathogen