Bacteria

1. Bacteria Bacteria are the most numerous organisms on Earth as well as the most ancient. They were probably the first forms of life. It is likely that all other organisms on Earth evolved from bacteria. About 90% of the bacteria on Earth are not harmful to humans. The remaining 10% can cause diseases that range from minor discomfort to death within a few days. As humans, our main weapon against bacterial infection is antibiotics. But due to misuse, antibiotic resistance is on the rise in bacteria, slowly decreasing the number and type of antibiotics we have to fight infection.

2. Evolution 1. bacteria are microscopic prokaryotes that are part of nearly every environment on Earth 2. bacteria are living organisms that are adapted to live where no other organism can (volcanoes, 6miles into the ocean, acid pools, digestive system)  Shape 1. most common shapes are bacillus(rod), cocci(circle), and spirilla(spiral)

4. E. coli bacteria (bacillus) (cocci) (spirillum)

5. Classification 1. Archaebacteria – live in extreme environments (acid pools, volcanic vents); Cell walls made without peptidoglycan 2. Eubacteria – bacteria we refer to as germs; account for most bacteria; Cell wall - peptidoglycan

6. Eubacteria Archaebacteria Living in soil Infecting large organisms Thick mud Animal digestive tracts Salty lakes Hot springs Bacteria are classified into the kingdoms of include a variety of lifestyles such as live in harsh environments such as

7. Heterotrophs Chemoheterotrophs – take in organic compounds for energy and carbon supply (humans) Photoheterotrophs – use sunlight for energy but take in organic compounds for carbon Autotrophs Photoautotrophs – use light to convert carbon dioxide and water to carbon compounds and oxygen (similar to photosynthesis); live in salt and fresh water Chemoautotrophs – do not require light to convert to carbon compounds (live deep in ocean where it is dark) Metabolic Diversity

8. Releasing Energy – by cellular respiration OR fermentation OR both • Obligate aerobes – require constant supply of oxygen • Obligate anaerobes – do not require oxygen (can be killed by it!) • Facultative anaerobes – can survive with or without oxygen (can switch between cellular respiration and fermentation) • Example – E. coli lives anaerobically in the large intestine and aerobically in sewage

9. Bacteria and Humans Pathology- scientific study of disease Pathogen- agents that cause disease If you had to count all the cells in your body, the vast majority would be microbes! There are 10 times more microbial cells than human cells in our bodies! Filamentous cyanobacterium, Anabaena sp. (SEM x5,000)

10. Human Infection 1. bacteria cause disease by producing poisons or toxins 2. bacteria enter body through orifices (eyes, mouth, nose, cut on skin, genital openings) 3. once inside body, bacteria reproduce by binary fission, essentially making copies of themselves 4. reproduce very quickly: can make millions of bacteria in 12 hours

11. Common Diseases Caused by Bacteria Disease Pathogen Prevention Regular dental hygiene Protection from tick bites Current tetanus vaccination Vaccination Proper food-handling practices Maintaining good health Clean water supplies 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

12. Antibiotics 1. drugs that combat bacteria by interfering with cellular function 2. derived from chemicals that bacteria synthesize 3. broad-spectrum antibiotics affect a wide variety of bacteria 4. patient must take a full course of antibiotics or risk resistance

13. Antibiotic Resistance 1. when bacteria are exposed to antibiotics the most vulnerable die first 2. if the antibiotic is stopped, bacteria that are still alive will mutate so the antibiotic will no longer affect them 3. bacteria living in the body are now resistant to antibiotic

14. Useful bacteria 1. most bacteria affect us positively 2. bacteria break down dead plant and animal matter to recycle carbon and nitrogen 3. bacteria produce and process food (sour cream, yogurt, cheese) 4. used to clean up oil and chemical spills 5. help us digest food

15. Prevention 1. good hygiene –wash hands, cover face when coughing and sneezing, wash cuts, do not exchange body fluids with sick people

16. Lyme Disease 1. acute, inflammatory infection that causes a skin rash, flu-like symptoms, and joint inflammation 2. caused by bacteria transmitted by the bite of a deer tick 3. symptoms include fever, headache, muscle pains, stiff neck, itching, a bulls-eye rash around site of bite 4. treatment includes antibiotics and pain relievers 5. if diagnosis occurs early it can be cured, if not, complications can occur in the heart and nervous system

18. Ribosome Peptidoglycan Pili Flagellum DNA Cell membrane Cell wall

19. Growth and Reproduction • When conditions are favorable, bacteria can grow and divide as often as every 20 minutes! • If unlimited space and food were available to a single bacterium and all of its offspring divided every 20 minutes, in just 48 hours they would reach a mass approximately 4,000 times the mass of the Earth!

20. Rod-Shaped Bacterium, E. coli, dividing by binary fission (TEM x92,750) Binary fission – Asexual reproduction in which a bacterium doubles its size, replicates its DNA, and divides in half producing 2 identical “daughter” cells

21. E. coli strains undergoing conjugation (TEM x27,700) Conjugation - bacteria exchange genetic information via a hollow bridge; creates genetic diversity in a bacteria population

22. Spore formation – when conditions become unfavorable bacteria can produce an endospore (a thick internal wall that encloses its DNA and a portion of the cytoplasm) Spores can be dormant for months or years while they wait for conditions to become more favorable

23. Viruses Viruses are nonliving substances that infect living things, causing diseases that range from the flu to Ebola. Since viruses are not living, they must infect cells of a living organism in order to replicate. Viruses have no cure, only treatments that manage the symptoms. Once a person is infected with a virus, it stays in the system for their lifetime. Although the person will not suffer from the symptoms continuously, the disease can reoccur throughout their life. Although there is no cure for viral infections, vaccines can be administered to prevent a person from contracting the disease in the first place.

24. Virus 1. nonliving particle (chemical) that causes disease in living organisms for which there is no cure, only treatment 2. no nucleus, no cytoplasm or organelles, no cell membrane 3. not capable of carrying out cellular functions, such as reproduction 4. able to replicate only by infecting cells and using organelles to make copies

25. RNA DNA Head RNA Capsid Capsid proteins Tail sheath Tail fiber Surface proteins Membrane envelope Virus Structures Tobacco Mosaic Virus T4 Bacteriophage Influenza Virus

27. Viral Structure 1. DNA or RNA and a protein coat (called a capsid) Viroids and Prions 1. Viroids- smallest particle known to replicate 2. Prion- abnormal forms of proteins that clump together inside a cell, eventually kills cell 3. Example of prion-caused disease: mad cow 

28. Infectious Disease 1. viral diseases are among the most widespread illnesses in humans 2. Examples: common cold, chickenpox, measles, mumps, polio, rabies, hepatitis, HIV, herpes Nucleic Acid Disease Type of Virus Cancer Cancer, AIDS Respiratory infections Chickenpox Smallpox Oncogenic viruses Retrovirus Adenoviruses Herpesviruses Poxviruses DNA RNA DNA DNA DNA Common Diseases Caused by Viruses

29. Rabies 1. transmitted by bite of infected animal (carries virus in saliva) 2. once infected, virus travels to central nervous system 3. symptoms include headache, fever, throat spasms, paralysis, coma 4. very few people survive effects

30. Chickenpox 1. highly contagious 2. transmission is through air or direct contact with rash 3. symptoms are fever and rash 4. after infection and recovery, individual usually has lifelong resistance to disease 5. can cause shingles later in life

32. Shingles 1. more severe than chickenpox: fever is higher, immune system weakens, pneumonia can occur 2. rash is painful and limited to one area or side of body 3. can shed chickenpox virus (someone who has shingles can infect a person with chicken pox if they haven’t had it already but cannot spread shingles

34. Smallpox 1. virus transmitted by nasal droplets emitted during sneezing or coughing 2. symptoms include fever, headache, rash 3. hardy enough to be spread through blankets/towels 4. aggressive vaccination program eradicated smallpox from the planet in 1980

37. Prevention 1. Vaccine – preparation of pathogens that stimulates immune system to manufacture antibodies to the disease * Vaccines cause the body’s immune system to react in a similar way to being infected with the actual virus. It allows the body to make antibodies to a virus before being infected with it. So when the person comes into contact with the virus, the body has already created its weapons to fight it.

38. 2. people get vaccines (shots or pills) as a small child or before international travel 3. vaccines contain dead or weakened virus 4. childhood vaccines: measles, mumps, rubella, polio 5. recent vaccines: hepatitis A and B 6. travel vaccines: typhoid, yellow fever, meningitis 7. booster shot – additional vaccine to extend your protection

39. Treatment 1. no cure for viral disease, only treatment to relieve symptoms 2. once infected with a virus, a person has it for life but does not always suffer from symptoms 3. antiviral medication can help control outbreaks Emerging viruses 1. Ebola, Hantavirus, Lassa fever

40. Protozoa  Protists are a diverse group that have been described as animal-like, plant-like, and fungus-like. They are single-celled, microscopic, and can move independently. They reproduce asexually, usually by binary fission. They can cause a wide range of human diseases including amoebic dysentery, sleeping sickness, and malaria. Malaria has killed more people around the world than any other disease

41. Human Diseases Amoebic Dysentery 1. passed in contaminated food and water 2. lives in the intestine 3. causes ulcers and diarrhea Tryptosomiasis 1. sleeping sickness 2. passed by tsetse fly 3. causes fever, mental deterioration, and coma

44. It is this pseudopodia movement that enables the amoeba to capture prey. The amazing thing is that the amoeba don't touch the ciliate until it can't escape. Usually the pseudopods form a kind of 'dome' that makes escaping impossible. They have to have some sort of chemical detection since they notice a prey without having to touch it.

45. Malaria 1. passed by mosquitoes 2. causes severe chills, fever, sweating, fatigue, and thirst 3. victims die from anemia, kidney failure, brain damage 4. when mosquito bites animal, sporosites travel to the liver and new spores emerge from liver called merozoites 5. merozoites infect red blood cells and reproduce

46. 6. red blood cells burst and release toxins into the body 7. drugs can prevent malaria and sometimes help a person survive the infection 8. different types of malaria –some fatal, others not

47. Areas of the world where malaria is endemic

48. Anopheles albimanus mosquito feeding on a human arm. This mosquito is a vector of malaria and mosquito control is a very effective way of reducing the incidence of malaria.