KEY CONCEPT Infections can be caused in several ways.

1. KEY CONCEPTInfections can be caused in several ways.

2. Any disease-causing agent is called a pathogen. 1 nanometer (nm) = one billionth of a meter 100 nm eukaryotics cells10,000-100,000 nm viroids5-150 nm viruses50-200 nm prokaryotics cells200-10,000 nm prion2-10 nm

3. Causes misfolding of other proteins • Results in diseases of the brain • A prion is made only of proteins.

4. A Virus is made of DNAorRNA and a protein coat. • Non-living pathogen • Can infect many organisms • A Viroid is made only of single-stranded RNA • Causes disease in plants • Passed through seeds or pollen

5. NO - nucleus, cytoplasm, organelles, or cell membrane NOT capable of carrying out cellular functions NOT alive! 18.2 Viral Structure and Reproduction Characteristics of Viruses

6. Obligate Intracellular parasites - depend on host cells for replication Spread by wind, water, food, blood or other bodily secretions Named for the disease they cause or the tissue they infect 18.2 Viral Structure and Reproduction Viruses

7. Nucleic acid Either DNA or RNA, but not both Helical, closed loop, or a long strand Protein coat surrounds nucleic acid (capsid) Some have a membrane like structure outside capsid called an envelope Ex: influenza, herpes, chickenpox, HIV 18.2 Viral Structure and Reproduction Viral Structure

8. Bacteriophages – virus that infects bacteria. 18.2 Viral Structure and Reproduction capsid DNA tail sheath tail fiber

9. 18.2 Viral Structure and Reproduction colored SEM; magnifications: large photo 25,000; inset 38,000x

10. http://www.youtube.com/watch?v=Rpj0emEGShQ Flu Attack

11. 18.2 Viral Structure and Reproduction

12. Virus - recognize and attach to a receptor site on the plasma membrane of host Protein on capsid locks with receptor site Each virus has a specifically shaped attachment protein (jigsaw puzzle) Can only attach to a few hosts 18.2 Viral Structure and Reproduction Attachment to a host cell

13. Lytic Lysogenic 18.2 Viral Structure and Reproduction Viruses cause two types of infections.

14. Virus invades a host cell  produces new viruses (transcription, translation and assembly)  immediately destroys host releasing newly formed viruses - virulent virus Lysis - cell disintegration 18.2 Viral Structure and Reproduction Lytic cycle

15. host bacterium The bacterophage attachesand injects it DNA into a host bacterium. The host bacterium breaks apart, or lyses. Bacteriophages are ableto infect new host cells. The viral DNA forms a circle. The viral DNA directs the hostcell to produce new viral parts.The parts assemble into newbacteriophages. Lytic Cycle

16. Infect a cell without causing its immediate destruction - temperate virus Viral DNA is integrated into hosts DNA – prophage Can stay in host cell for an extended period of time Every time host cell reproduces = prophage is replicated Every cell is also infected Trigger will activate lytic cycle later Ex: Herpes, chicken pox 18.2 Viral Structure and Reproduction Lysogenic Cycle

17. Lysogenic Cycle The prophage may leave the host’s DNA and enter the lytic cycle. The viral DNA is called a prophage when it combines with the host cell’s DNA. Although the prophage is not active, it replicates along with the host cell’s DNA. Many cell divisions produce a colony of bacteria infected with prophage.

18. RNA viruses Most complex replication cycle Ex: HIV Once inside host retrovirus makes DNA Reverse transcriptase – produce DNA from viral RNA Then it is integrated and becomes a prophage If reverse transcriptase is in a person then they have been infected with a retrovirus 18.2 Viral Structure and Reproduction Retroviruses

19. Rabies - transmitted by the bite of an infected animal virus is carried in saliva virus travels from wound to central nervous system fever, headache, throat spasms, paralysis, coma 18.3 Viral Diseases Common human viral diseases

20. Virus multiplies in lungs, uses blood vessels to reach skin Fever, skin rash Transmission from direct contact with the skin rash and through the air Recover - usually followed by a lifelong resistance to re-infection Can persist in nerve cells as a prophage - cause shingles later in adulthood Fever is higher Immune system weakens Pneumonia may occur 18.3 Viral Diseases Chicken pox

21. Human immunodeficiency virus Infects white blood cells Prophage eventually enters lytic cycle leading to rapid decrease in white blood cells AIDS - acquired immunodeficiency syndrome Person dies from other infections 18.3 Viral Diseases HIV

22. Treatment Antiviral Drugs- interfere with viral nucleic acid synthesis Prevention Vaccination - stimulates body’s immune system to provide protection against that pathogen Inactivated - viruses do not replicate in a host system Attenuated - viruses are genetically altered so that they are incapable of causing disease under normal circumstances (preferred - protection is greater and lasts longer) 18.3 Viral Diseases Prevention and Treatment

23. 18.3 Viral Diseases

24. 18.4 Bacteria and Archaebacteria KEY CONCEPT Bacteria and Archaeabacteria are both single-celled prokaryotes.

25. Classification: Kingdom: Monera Eubacteria (germs) & Archaeabacteria 18.4 Bacteria and Archaebacteria Bacteria

26. Unicellular No nucleus No membrane-bound organelles Alive! Can do cell functions! 18.4 Bacteria and Archaebacteria Microscopic Prokaryotes

27. Unusual lipids (fats) in their cell membranes Introns (junk) in their DNA Cell wall lacks Peptidoglycan (protein carbohydrate compound found in cell walls of eubacteria) 18.4 Bacteria and Archaebacteria Archaebacteria: The extremists

28. Methanogens - convert hydrogen and carbon dioxide into methane gas Live in anaerobic conditions ex: bottom of a swamp and sewage, intestinal tract of humans and other animals Extreme Halophiles - live in high salt concentrations Use salt to generate ATP 18.4 Bacteria and Archaeabacteria Extreme Environments: Examples

29. Thermoacidophiles - live in extremely acidic environments that have extremely high T T up to 110 degrees C (230 degrees F) Ph less than 2 Hot springs, volcanic vents, hydrothermal vents 18.4 Bacteria and Archaeabacteria

30. Rod-shaped - bacilli Spiral - spirilla or spirochetes Spherical – cocci Streptococci – chains of cocci Staphylococci – grapelike clusters of cocci Vibrio - coma shaped Lactobacilli: rod-shaped Spirochaeta: spiral 18.4 Bacteria and Archaebacteria Eubacteria commonly named for shape Enterococci: spherical

31. 18.4 Bacteria and Archaebacteria Staphylococci Eubacteria: Streptococci

32. Cell membrane - contains enzymes that catalyze the reactions of cellular respiration DNA is a single, closed loop 18.4 Bacteria and Archaebacteria Eubacteria structure

33. Capsule - outer covering made of polysaccharides (sugars) protect it against drying out or harsh chemicals Pili - short hair-like protein structures found on the surface of some species of bacteria *help bacteria adhere to host cells *used to transfer genetic material 18.4 Bacteria and Archaebacteria

34. Flagella - turn and propel the bacterium (single or multiple) 18.4 Bacteria and Archaebacteria Movement Structures • Layer of slime - wavelike contractions of outer membrane propel it • Spiral - shaped bacteria move by corkscrew-like rotation

35. pili plasmamembrance flagellum chromosome cell wall plasmid This diagram shows the typical structure of a prokaryote. Archaea and bacteria look very similar, although they have important molecular differences. 18.4 Bacteria and Archaebacteria

36. Dormant structure that is produced by some (gram-positive) bacterial species that are exposed to harsh environmental conditions Help bacteria resist high temperatures, harsh chemicals, radiation, drying and other environmental extremes Conditions become favorable endospore will open, allowing the living bacterium to emerge and multiply 18.4 Bacteria and Archaebacteria Endospores

37. Gram staining identifies bacteria. Gram-negative bacteria have a thin layer of peptidoglycan and stain red. Gram-positive bacteria have a thicker peptidoglycan layer and stain purple. 18.4 Bacteria and Archaebacteria • stains peptidoglycan • gram-negative - stains pink - less peptidoglycan • gram-positive - stains purple - more peptidoglycan

38. Examples: Streptococci - causes strep throat Grow in milk producing lactic acid  yogurt Lactobacilli - found on teeth cause tooth decay Actinomycetes - form branching filaments, found in soil, and produce antibiotics Exotoxin- secreted into the environment and cause disease 18.4 Bacteria and Archaebacteria Gram-positive bacteria

39. Examples: Escherichia coli - lives in human intestine where it produces vitamin K and assists enzymes in the breakdown of foods Salmonella - responsible for food poisoning Chemoautotrophs Endotoxin- Not released until bacteria die 18.4 Bacteria and Archaebacteria Gram-Negative Bacteria

40. 18.4 Bacteria and Archaebacteria * Gram positive and gram negative have different susceptibilities to: • antibacterial drugs • produce different toxic materials • react differently to disinfectants

41. Heterotroph Saprophyte - feed on dead and decaying material parasitic Autotroph Photoautotrophs - sunlight to make E (Cyanobacteria) Chemoautotrophs – chemicals to make E 18.4 Bacteria and Archaebacteria

42. Photosynthetic Encased in a jellylike substance and often cling together in colonies Eutrophication - population bloom - sudden increase in the number of an organism due to large increase of nutrients 18.4 Bacteria and Archaebacteria Cyanobacteria (Blue-Green algae)

43. Obligate anaerobes - are poisoned by oxygen Obligate aerobes - need oxygen Facultative aerobes - live with or without oxygen 18.4 Bacteria and Archaebacteria Eubactria can be grouped by their need for oxygen.

44. Examples: Obligate Anaerobes - Clostridium tetani Facultative aerobes - E. coli Obligate Aerobes - Mycobacterium tuberculosis 18.4 Bacteria and Archaeabacteria

45. Binary Fission rapid 18.4 Bacteria and Archaebacteria Asexual Reproduction

46. Transformation - bacterial cell takes in DNA from external environment Conjugation - two bacteria bind together one transfers genetic information to the other Pili binds to bacteria to form a conjugation bridge 18.5 Beneficial Roles of Prokaryotes 18.4 Bacteria and Archaebacteria Genetic Recombination

47. conjugation bridge TEM; magnification 6000x 18.4 Bacteria and Archaebacteria

48. 18.5 Beneficial Roles of Prokaryotes KEY CONCEPTProkaryotes perform important functions for organisms and ecosystems.

49. Live in digestive systems of animals. make vitamins break down food 18.5 Beneficial Roles of Prokaryotes Provide nutrients to humans and other animals.

50. Ferment many foods. 18.5 Beneficial Roles of Prokaryotes • yogurt, cheese • pickles, sauerkraut • soy sauce, vinegar