CHAPTER 19: Bacteria and Viruses

Importance of Bacteria Producers – Photosynthesis Decomposers – Break down dead matter Recycle nutrients within ecosystem Nitrogen Fixers – Convert Nitrogen gas into a usable compound such as ammonia Required by plants Uses of bacteria Sewage treatment Environmental cleanup and mining Enzymes for medicine, food production, and chemistry Genetic engineering Human digestive function

19-2: Discovery of Viruses Dimitri Ivanovski 1892 –studied tobacco plants –Juice from crushed leaves killed healthy plants –named it tobacco mosaic disease

19-2: Viruses Particles of nucleic acids, proteins, and sometimes lipids. DNA or RNA core surrounded by a protein coat Protein coat called a CAPSID –Proteins bind receptors on host cells. –Virus gains access into cell. - Very specific to cells they infect.

Virus Structures Recall phages from Chapter 12. Which scientists worked with them? Describe the experiment and its results.

Viral Infections Lytic Cycle Virus enters cell, makes copies, and bursts or lyses cell Lysogenic Cycle Viral DNA integrates into host cell’s DNA Viral genetic info replicates with cell’s DNA Prophage is viral DNA in host genome

Lytic vs Lysogenic Cycles

Influenza Infection EGShQhttp:// EGShQ

Retroviruses Contain RNA –After infection, they produce DNA from their RNA –How do they accomplish this? –Recall Chapter 12 –AIDS, Hepatitis B –Ebola

DISEASE BACTERIAL OR VIRAL EFFECT ON BODY TRANSMISSION West Nile V Fever, Headache, Body Aches Mosquito Bite Tetanus B Lockjaw, Joint stiffness, fever, High BP Inhalation AIDS V Helper T cells destroyed (Immune System) Blood, Body Fluids, Pregnancy Hepatitis B V Fatigue, Abdom Pain Vomiting, Joint Pain Blood, Body Fluids Common Cold V Sneezing, Sore throat, Headache, Fever Contact with objects, Inhalation Strep Throat B Fever, Sore throat, cough, Fatigue Contact with mucus or wounds

Are Viruses Alive? Viruses are not considered living things. Do not meet all 8 characteristics of life Cannot reproduce independently No growth/development Do not use/obtain energy

19-3: Diseases Pathogens are disease-causing agents. Bacterial Diseases –Break down cells for food –Mycobacterium tuberculosis infects lung cells –Release toxins that disrupt cell functions –C. diphtheriae  diphtheria –Breathing problems, paralysis, death

Preventing Bacterial Disease Vaccines and Antibiotics Louis Pasteur 1881 –Developed vaccine against anthrax Alexander Fleming 1928 –Discovers penicillin –Non-toxic but stops growth of pathogens Jonas Salk 1952 –Polio vaccine using a dead virus

Controlling Bacterial Growth Heat Sterilization Disinfectants Why is overuse dangerous? Food Storage and Processing Refrigeration and cooking methods

Viral Diseases Antibiotics ineffective. Best protection is vaccines. Viroids and Prions also cause disease Single stranded RNA with no capsid Made of protein with no DNA/RNA