Chapter 19 Bacteria and Viruses TB AIDS Microbiology

Chapter 19 Bacteria and Viruses TB AIDS

Microbiology • Bacteria are the most numerous and diverse of all organisms, and live anywhere on the planet. • There are two kingdoms of bacteria: 1. Archaebacteria (more ancient, examples here on this slide) 2. Eubacteria

Archaebacteria • Bacteria that do not contain peptidoglycan (a protein/carbohydrate used for structure/support) in their cell walls • This type of bacteria lives in extreme environments – Methanogens (anaerobic conditions) – Extreme halophiles (use salts to make their energy) – Thermoacidophiles (extreme temperatures & p. H)

Methanogens • Convert hydrogen and carbon Dioxide into methane gas (CH 4) using an alternate form of photosynthesis (no oxygen!) • Found in swamp gas and sewage

Extreme Halophiles • Survive and thrive in very salty conditions • Use this salt to generate ATP

Thermoacidophiles • Survive and thrive in extreme temperatures or extremely acidic environments

Gram Stain • Eubacteria contain peptidoglycan (sugar/protein) in their cell walls • Bacteria types can be determined by Gram staining. – Developed by Hans Gram in 1884 to differentiate between bacteria types. – Gram stain positive (eubacteria) bacteria will stain a violet color. • Ex. Listeria, Streptococcus – Gram stain negative (archaebacteria) bacteria will turn a red or pink once counter-stained. • Ex. Meningitis and Salmonella

Shapes of Eubacteria

Even More Types of Bacteria • Obligate aerobes – require a constant supply of oxygen to live. – Humans and many species of bacteria • Obligate anaerobes – must live in the absence of oxygen – C. botulinum • Facultive anaerobes – can survive with or without oxygen – Impacts type of respiration; can survive in any environment!

Bacteria Diagram • What’s the difference between a prokaryote (bacteria) and a eukaryote? • Cell wall • Cell membrane • Flagella • Pilus or Pili • Ribosomes • DNA • Cytoplasm

Pili or Pilus • What do you think its function is? • Found in grampositive bacteria • Protein tubes with an adhesive tip that corresponds to a specific glycoprotein • Constantly making and losing pili to diversify tips

Binary Fission • Division of a bacterial cell into two genetically identical cells. – Origin of replication • One bacterial cell can become one billion in just 10 hours! • If conditions are unfavorable for reproduction, bacteria can form an endospore!

Genetic Recombination • Bacteria are asexual (previous slide) • BUT, there are three ways they can exchange genetic information: – Transformation – extracts DNA from an outside source – Transduction – virus uses part of bacterium to replicate its own DNA (review) – Conjugation – two bacteria bind together and one transfers DNA into the other

Diseases caused by Bacteria • Pathogen = disease causing agent • Three ways that bacteria can cause infectious diseases: – Metabolize their host (via food) – Secrete bacterial toxins – Biowarfare – Anthrax • Examples: Botulism and Salmonella (food poisoning), Lyme disease (ticks), Strep throat (Streptococcus) • Sterilization

Uses of Bacteria • • Nitrogen cycle Food Environmental Mining (video #2) Uranium cleanup Cheese making Pickle making

Today’s Videos – watch at your leisure! 1. https: //youtu. be/ypmsjqyt. Mp. A (flesh eating) 2. https: //youtu. be/THRgkllfj 1 A

Viruses • Non-living particle • Discovered by Wendell Stanley in 1935 – Working with Tobacco Mosaic Virus (TMV) • Virology is the study of diseases, studied by virologists

Diversity of Viruses

Common Viral Diseases • • Common cold Influenza (flu) Chickenpox Rabies – transmitted through animals Herpes – different types HIV (the virus)/AIDS (the disease) Cancer

Zika Virus • Spread to humans through infected mosquitoes • Mild symptoms unless… • Infection during pregnancy can result in microcephaly and other brain defects

Viral Replication – terms • Bacteriophage – viruses that infect bacteria (the host in which they replicate their genome) • Prophage – the viral DNA that is imbedded in the host’s DNA – Will ultimately direct the host DNA to synthesize new viruses T 4 Bacteriophage

Lytic Cycle • Virulent • Virus invades a host cell – Bacteriophages are one way this can happen • Immediately takes over the cell’s machinery – DNA, ATP, ribosomes, etc. to make copies of itself • Lyses (bursts) cell open to kill it and send it’s “viral army” out to infect other cells.

Lysogenic Cycle • Temperate • Virus invades a host cell • Combines with the host’s genome to make a (repressed) provirus – Replicates with the host – Can wait for years • Due to an stress-inducing event, it becomes active, the host recognizes it, and it’s “kicked out” of the cell.

Prions and Viroids • • Prions A typical grouping of proteins that act like viruses and take over your nerve cells. Most often affect the brain BSE (Bovine Spongioform Encephalopathy) aka mad cow disease Cusp of Alzheimer’s research Viroids • Smallest known particles able to reproduce. – As small as 250 nucleotides! • Virus-like • Able to disrupt plant cell metabolism • Plants affected: oranges, potatoes, and cucumbers.

Prions

BSE/Mad Cow Disease

Viroids

Vaccines • The best way to protect against most viral diseases • A preparation of weakened or killed virus or even just viral proteins injected into the human body – How does this help? • This vaccine stimulates the immune system, fortifying in the event that the virus comes your way.