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Emerging Diseases

Emerging Diseases . BIOL 119 Spring, 2011 Some Types of Germs. Germs (pathogens) are disease-causing agents. Pathogens are transmissible agents of disease The organism that “catches” the disease is called the host . Pathogens grow and reproduce in and on the host.

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Emerging Diseases

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  1. Emerging Diseases BIOL 119 Spring, 2011 Some Types of Germs

  2. Germs (pathogens) are disease-causing agents • Pathogens are transmissible agents of disease • The organism that “catches” the disease is called the host. • Pathogens grow and reproduce in and on the host. • Poisons and toxins do not grow and reproduce. • Some pathogens are alive and some are not alive.

  3. Topics • Pathogens that are alive • Pathogens that are not alive • Characteristics of some pathogens • Summary

  4. Pathogens that are alive…… According to the Cell Theory, all living things are made of one or more cells. Therefore, living pathogens have to have cells. Microscopic and macroscopic living pathogens

  5. Types of living pathogens • Bacteria-microscopic and unicellular • Fungi-microscopic and unicellular • Parasites microscopic and unicellular (amoebas and similar organisms) macroscopic and multicellular (worms)

  6. Two types of cells based on structure • Prokaryotes-cells without a nucleus • Usually small • Relatively simple • Bacteria • Eukaryotes-cells with a nucleus • Much larger • More complex • Fungi and parasites These pictures are for size comparisons

  7. Cells with and without nucleus Prokaryotes do not have a nucleus They have a nucleoid for DNA Eukaryotes have a highly organized nucleus for their DNA

  8. Eukaryotic cells have many shapes

  9. Bacteria have only a few shapes Coccus (cocci) Bacillus (bacilli) Spirillum (spirilli) Mycoplasma

  10. Pathogens that are not alive They are not made of cells There are 2 types viruses (influenza) sub-viral pathogens (mad cow)

  11. Characteristics of Germs- Parasites Includes single-celled protozoa as well as multicellular organisms Eukaryotes Protozoa are very diverse-Plasmodium, Giardia, Pneumocystis, Cryptosporidium May live within body cavities or may burrow deep into soft tissues Worms associated with unsanitary conditions

  12. Characteristics of Germs- Fungi Eukaryotic cells May live in visible colonies or as individual cells Specialists at living on other organisms Cell wall made of chitin

  13. Characteristics of Germs- Bacteria Single prokaryotic cells Living pathogens Simple life style Ready to take advantage of opportunity Most have rigid cell wall, primitive types do not e.g. mycoplasmas

  14. Characteristics of Pathogens-Viruses Nonliving, noncellular Very small (electron microscope) Simplest ones consist of only a few genes (RNA or DNA) protected by a protein coat Require cells to reproduce

  15. Characteristics of Pathogens-Sub Viral Pathogens Aware of only one type right now-prions Nonliving, noncellular Very small (electron microscope) They do not have genes They cause healthy proteins to flip into a disease state but do not reproduce

  16. Types of Germs and Their DiseasesSummary • Parasites-tapeworms, amoebas, protozoa • Fungi- athlete’s foot, yeast infections • Bacteria-anthrax, syphilis, Staph infections • Viruses- AIDS, cervical cancer (HPV), influenza • Sub-viral- Mad Cow

  17. January 28, 2011 THE NEW YORK TIMES Pneumonia DNA Morphs To Dodge Vaccines By SINDYA N. BHANOO Researchers from seven countries have collaborated to analyze how a single strain of Streptococcus pneumoniae bacteria has morphed over 30 years and spread across the world, in an attempt to overcome the development of antibiotics and vaccines. The research is the first detailed genetic picture of the evolution of a specific strain of pneumonia, resulting in a family tree of sorts. The researchers analyzed samples from North and South America, Africa and Southeast Asia. Their findings appear in the current issue of the journal Science. In looking at more than 240 samples, they found that since 1984, when the strain was first identified in Spain, it has turned over about three-quarters of its genome. Over time, the bacteria mutated to better resist antibiotics and vaccines. The researchers found that it underwent both recombination, in which the DNA shuffles around, and base substitutions, in which individual nucleic acids in a DNA sequence change. That means that certain samples they tested are not treatable with existing vaccines, which target certain gene clusters that have now changed. In the past, genomic sequencing of bacteria was time-consuming and laborious, but new technology has sped up the process, and will perhaps help speed up the development of new vaccines, said Stephen Bentley, a geneticist at the Wellcome Trust Sanger Institute and one of the study’s authors. “I think this going to be really important going forward,” he said. “We can start to do this kind of analysis routinely; then we will be able to have really valuable information for how to introduce antibiotics and new vaccines.” He and his colleagues are now studying several other strains of the pneumonia bacteria.

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