Immune System Viruses vs. Bacteria
Concept Map Section 19-1 Bacteria are classified into the kingdoms of Eubacteria Archaebacteria include a variety of lifestyles such as live in harsh environments such as Living in soil Infecting large organisms Thick mud Animal digestive tracts Salty lakes Hot springs Go to Section:
The Structure of a Eubacterium Section 19-1 Peptidoglycan Cell wall Cell membrane Ribosome Flagellum DNA Pili Go to Section:
Importance of Bacteria Vital to maintaining the living world Producers that capture energy by photosynthesis Break down nutrients in dead matter and atmosphere, allowing other organisms to use the nutrients
Identifying Bacteria Shapes Rod = Bacilli Spherical = Cocci Spiral/Corkscrew = Spirilla
Identifying Bacteria Cell Walls (chemical nature) Stain tells the two apart ( Gram stain ) Purple dye = primary stain Red dye = counter stain Gram Positive = cell wall containing peptidoglycan absorb only purple dye Gram Negative = cell wall containing lipid and carbohydrate absorb red dye
Identifying Bacteria Movement Flagella = whip like structures Some lash, snake or spiral forward Glide along a layer of slime like material they secrete Some don t move
Section 19-2 Common Diseases Caused by Bacteria Disease Pathogen Prevention Tooth decay Lyme disease Tetanus Tuberculosis Salmonella food poisoning Pneumonia Cholera Streptococcus mutans Borrelia burgdorferi Clostridium tetani Mycobacterium tuberculosis Salmonella enteritidis Streptococcus pneumoniae Vibrio cholerae Regular dental hygiene Protection from tick bites Current tetanus vaccination Vaccination Proper food-handling practices Maintaining good health Clean water supplies Go to Section:
Bacteria and Disease Bacteria cause disease in one of two general ways: 1. some damage the tissues of the infected organism directly by breaking them down for food (tuberculosis) 2. Release toxins (poisons) that harm the body (food poisoning)
Bacteria and Disease Most bacteria are not bad, just a few, they are called pathogens Pathogen comes from the Greek words pathos suffering and genes born or produced, so pathogen means produces suffering
Bacteria and Disease Many bacterial diseases can be prevented by stimulating the body s immune system with vaccines Antibiotics can also block the growth and reproduction of bacteria (penicillin)
Human Uses of Bacteria Food = cheese, yogurt, buttermilk, sour cream, some pickles, sauerkraut, and vinegar Industry = clean up oil spills and waste, mine minerals, synthesize drugs/medicines
Controlling Bacteria Sterilization = destroys it with heat or chemicals (disinfectants like Lysol) Refrigeration = bacteria grow slowly at lower temps Boiling, Frying, Steaming = high temps kill Canning = allows for long storage Chemicals = salts, vinegar, sugar
Viruses Particles of nucleic acid, protein, and in some cases lipids that can reproduce only by infecting living cells Structure: Core of either DNA or RNA Capsid = protein coat genes
Virus Structures Section 19-3 Head T4 Bacteriophage DNA Tobacco Mosaic Virus RNA Influenza Virus Capsid proteins Capsid RNA Tail sheath Tail fiber Surface proteins Membrane envelope Go to Section:
Viral Infection Viruses must bind precisely to proteins on cell surface and then use a host s genetic system = making them very specific to the cells they infect (plant vs. animal viruses) Example = bacteriophages Two types: Lytic infection Lysogenic infection
Lytic Infection Virus enters a cell, makes copies of itself, and causes the cell to burst (lyses)
Figure 19-14 The Lytic Cycle Section 19-3 Bacteriophage protein coat Bacteriophage DNA Bacterial chromosome Bacteriophage attaches to bacterium s cell wall Bacteriophage enzyme lyses the bacterium s cell wall, releasing new bacteriophage particles that can attack other cells. Lytic Cycle Bacteriophage injects DNA into bacterium Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles Bacteriophage takes over bacterium s metabolism, causing synthesis of new bacteriophage proteins and nucleic acids Bacteriophage Bacteriophage DNA Bacteriophage protein Go to Section:
Lysogenic Infection A virus embeds its DNA into the DNA of the host cell and is replicated along with the host cell s DNA Viral DNA = prophage Certain conditions can cause a lysogenic virus to enter the lytic cycle
Figure 19-15 A Lysogenic Infection Section 19-3 Bacteriophage DNA Bacterial chromosome Bacteriophage injects DNA into bacterium Bacteriophage DNA (prophage) can exit the bacterial chromosome Lytic Cycle Lysogenic Cycle Bacteriophage enzyme lyses the bacterium s cell wall, releasing new bacteriophage particles that can attack other cells Bacteriophage DNA forms a circle Prophage Bacteriophage DNA (prophage) may replicate with bacterium for many generations Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles Bacteriophage DNA inserts itself into bacterial chromosome Go to Section:
Viruses and Disease Human diseases = polio, measles, AIDS, mumps, influenza, yellow fever, rabies, and common cold Cancer Retroviruses = contain RNA as genetic info (AIDS) Prions = protein infection particles that contain no DNA or RNA (mad cow)
Are Viruses Alive? They share the genetic code w/ living things and affect living things but most scientists do not consider them alive because they are not cells and are not able to reproduce independently