BACTERIA AND VIRUSES

What Are Bacteria? Prokaryotic Small (1-5 um) and Unicellular No Nucleus No Mitochondria or Chloroplast Single Chromosome Small (1-5 um) and Unicellular 100 trillion in the body. That’s 100,000,000,000,000 cells! Compared to 10 trillion human cells. 10:1 ratio Used to be grouped as Monera

Archaebacteria vs. Eubacteria Differences that resulted in the two-kingdom classification structure for bacteria include: Biochemical differences such as cell wall and plasma membrane composition Structure and function of genetic material particularly tRNA and rRNA base sequences (archaebacteria are actually more similar to eukaryotes, and lack peptidoglycan in the cell walls) Reactions to antibiotics

Eubacteria: includes most of the “common” bacteria Heterotrophs: these use organic molecules as food sources. Some are parasites, others are saprophytes (feeding on dead organisms or wastes). Photosynthetic autotrophs: includes cyanobacteria. These are often found in long chains of cells. Chemosynthetic autotrophs: these can make their own food, but they don’t undergo photosynthesis. Instead, they break down sulfur and nitrogen containing inorganic compounds.

Archaebacteria: thrive in extreme conditions Methane producers: these thrive in oxygen-free environments (such as the digestive tracts of cows, marshes, and lake sediments). These are important in sewage disposal plants where they assist with the breakdown of sewage. Salt-loving bacteria: these live in bodies of water with high levels of salts. Ex: Great Salt Lake, Dead Sea. Heat and acid-loving bacteria: these thrive in hot, acidic waters such as sulfur springs and hot ocean vents (temps can be above the boiling point).

Basic structure of bacteria They can also have other structures such as flagella (long, whip-like projections that can be used for movement) and pili (extensions of the plasma membrane). The DNA is circular and often separate pieces exist called plasmids.

Shapes of Bacteria Bacilli (rod-shaped) Ex. Bacillus anthracis (Anthrax) Spore forming Inhalation of these spores into lungs Treatment for Anthrax Antibiotics like penicillin if used soon after exposure

Shapes of Bacteria Cocci (spherical shaped) Streptococcus aureus Cures Strep throat Usually found in clusters Cures Antibiotics (stops replication of cells)

Shapes of Bacteria Spirilla (Spiral shaped) Vibrio cholerae (Cholera) Spread through contaminated water, food Shellfish & plankton Other filter feeders Symptoms: Severe diarrhea, vomiting and dehydration. Treatment: rehydration salts, and antibiotics

Reproduction Binary fission Conjugation Similar to what process in humans? Why is it different? Can happen every 20 minutes (E. coli) Why don’t bacteria take over the world? Conjugation Exchange genetic material (antibiotic res.)

Where do Bacteria Live? In You!! Skin Mouth--over 500 different types of bacteria!! S. mutans Plaque formation and cause of cavities Favorable environment

Bacteria in Your Mouth

Where do Bacteria Live? In You!! Intestinal Tract E. coli Most abundant in lower GI tract

Where do Bacteria Live? Inanimate objects Water fountain Door handles Keyboards Silverware Lockers Dirty gym socks

Where do Bacteria Live? Water Coliform Bacteria What are Coliforms? Total Coliforms Fecal Coliforms What are Coliforms? Indicators for pathonogenic bacterium Where are they found? In rivers, lakes, swimming pools(?), drinking water(?)

Sources of Coliform Bacteria Sewage (fecal coliforms) Warm blooded mammals’ fecal material Livestock Cows CAFOs Pollution Industry Agricultural

Beneficial Bacteria Used in making foods Cheese (Penicillin Roqueforti = blue cheese) Wine & Beer, sauerkraut, yogurt Oil spills Intestinal – antagonistic and mutualistic Wastewater treatment plants

viruses

Bacteriophages Viruses that infect BACTERIA Bacteriophages are used to insert DNA into another organism Bacteriophages will be shown in the animation describing the two different replication cycles of all viruses The LYTIC cycle is an active virus which KILLS the cell The LYSOGENIC virus is integrated into the host DNA and HIDES inside the cell

Lytic Virus Lytic Bacteriophage

5 Steps in the Lytic Cycle Attachment Entry Replication Assembly of new viruses LYSIS: cell breaks open and releases new viruses into the organism or environment

Lysogenic Virus Prophage infection

8 steps of the Lysogenic Cycle Attachment Entry Integration into the host cell’s DNA (prophage or provirus) Replication of cells (including virus DNA) Trigger Replication of Virus Assembly Lysis

Common Viruses Flu Virus HIV: Retrovirus Herpes Simplex I Chicken pox virus (shingles) West Nile Virus: most people infected never know they have it! Flu Virus

Vaccines: the war against the virus Prevention by injecting WEAKENED or “KILLED” virus particles to cause your immune system to recognize the virus quickly When in contact with the real virus, your IMMUNE SYSTEM should recognize the virus and come to the rescue