Chapter 2 – Diversity: From Simple to Complex

1. Chapter 2 – Diversity: From Simple to Complex Classifying the `Invisible` that we are unable to see without the aid of microscopes

2. A Microscope Look at life`s organization SBI 3U Section 2.1 pp.52 - 58

3. Prokaryotes & Eukaryotes • Recall: • Mitosis – cells • divide toform • two cells that are • identical to the • parent cell. • Meiosis – • produces the • reproductive • cells (sperm & • egg) which have half the number of chromosomes as the parent cell

4. Viruses A structure that contains strands of DNA or RNA surrounded by a protective protein coat; it cannot live independently outside of cells Characteristics: • Are not cellular and don’t have cytoplasm, membrane bound organelles or cell membranes. • Do not fit the 6-kingdom system (not ``alive``) • Outside of a living cell, a virus is a lifeless chemical (dormant) • No life function on its own • Only when a virus invades a living cell, does it start to reproduce and `come alive`

5. Classifying Viruses 1) Size and shape ofcapsid (outer protein layer that surrounds the genetic material of a virus) 2) Types of diseases they cause. Polio Virus HIV Tobacco Mosaic T4 Virus Virus

6. Bacteriophage Viruses that infect and destroy bacterial cells (eaters of bacteria) e.g. T4 Virus

7. Reproduction in Viruses Viruses undergo replication within a host cell Viruses use the host cell to produce multiple copies of themselves. This typical replication cycle of viruses is called the LYTIC CYCLE Lytic Cycle is the replication process in viruses in which the virus’s genetic material uses the copying machinery of the host cell to make new viruses

8. Reproduction in Viruses

9. Reproduction in Viruses However, sometimes the virus’s genetic material enters the nucleus of the host cell becoming a provirus. Replication will then occur through the LYSOGENIC CYCLE Lysogenic Cycleis the replication process in viruses In which the viral DNA enters the host cell’s chromosome; it may remain dormant and later activate and instruct the host cell to produce more viruses

10. Reproduction in Viruses

11. Viruses & Disease Lytic Cycle Viruses  Newly formed viruses burst form the host cell, usually killing it.  In multicellular hosts, these newly formed viruses infect neighbouring cells RESULT: damage to host varies Lysogenic Cycle Viruses (provirus)  Effects to the host might not be immediate E.g. HIV (Human Immunodeficiency Virus) leads to AIDS (Acquired immune deficiency syndrome)

12. A Retrovirus Retrovirus’ contain an enzyme that causes the host cell to copy viral RNA into DNA. This DNA becomes a provirus that continues to produce new viruses without destroying the cell This process can continue for years, with no harm to the host. However the provirus can separate from the host chromosomes at any time and complete the more damaging lytic cycle

13. A Retrovirus

14. PRIONS: Non-viral diseases causing agents Prions are infectious particles that causes damage to nerve cells in the brain. • Prions are proteins that are normally found in the body • Disease causing agents that lack RNA or DNA Prions seem to behave like a viral infection, BUT they are NOT, as there is no RNA or DNA. Disease results when prions change their molecular shape, while maintaining their chemical composition and become deadly. Example: Creutzfeldt-Jakob disease (CJD) Bovine spongiform encephalopathy (BSE) Scrapie in sheep

15. Viruses & Biotechnology Viruses have the ability to enter host cells and direct the activity of the host cell’s DNA Genetic engineers are using viruses to introduce specific genes into the host cell 1) Insert the gene into the genetic material of the virus 2) Virus enters host cell and directs the cell to make multiple copies of the virus 3) Each new virus in each new cell contains the added gene

16. To Do List • Learning Check, p. 55 #2, 5 • Review Questions, p. 58 # 1 – 15

17. Comparing bacteria and archaea SBI 3U Section 2.2 pp. 59 – 66

18. Bacteria vs. Archaea Bacteria and Archaea are more different from each other than an apple tree is from a blue whale Result  Three domains were established above the kingdom rank Domain Bacteria contains Kingdom Bacteria Domain Archaea contains Kingdom Archaea

19. Morphology - Size Bacillus are rod shaped forms of Bacteria and Archaea

20. Morphology - Shape Spherical forms are called cocci (plural) or coccus (singular) Enterococcus – found in intestines of warm blooded animals

21. Morphology - Shape Rod forms are called bacilli (plural) or bacillus (singular) E.Coli – found in intestines (cows), strain 0157 can lead to food poisoning in humans

22. Morphology - Shape Spiral shaped

23. Aggregations: Cells Grouped Together Streptococcus bacteria are found in chains of spheres Some individual prokaryotic cells (bacteria or archaea) group together Streptobacillus bacteria are rod shaped and found in chains

24. Comparing Nutrition Archaea  process of methanogenesis to obtain nutrients. Methanogenesis is an anaerobic process that occurs in environments that lack oxygen Some Archaea use sunlight as a source of metabolic energy but no reliable evidence of photosynthesis. Bacteria  some are photosynthetic Example: Cyanobacteria use solar energy to convert carbon dioxide and water into sugar and oxygen.

25. Comparing Habitats Both archaea and bacteria occupy environments with oxygen (aerobic) and without oxygen (anaerobic) Archaea  ability to live in extreme environments called extremophiles. Refer to Table 2.2 pg. 61 Bacteria  organisms that occupy environments with moderate (less extreme) conditions called mesophiles. There are few extremophilic bacteria.

26. Habitats of Extremophiles

27. Reproduction – Binary Fission Prokaryotes reproduce through the asexual process of binary fission  producing two genetically identical cells The Genetic material in prokaryotes is contained in a single chromosome within the cell. This chromosome is replicated during binary fission. When the cell reaches a certain size, it elongates, separating the original chromosome and its copy. A partition called a septum then forms between the 2 chromosomes and the cell splits.

28. Conjugation Conjugation  there is transfer of genetic material (DNA), involving two cells (prokaryotes), producing cells with new genetic combinations thus increasing genetic diversity Plasmids are small loops of DNA that are separate from the main chromosome and can also be transferred. A bridging structure transfers DNA material from one cell to another

29. Endospores: Protecting Genetic Material Endospores  dormant bacterial cells  able to survive for long periods during extreme conditions E.g. freezing or high temperatures, radiation & toxic chemicals)

30. Identifying Bacteria & Archaea A Gram stain is usedto divide bacteria into 2 groups Gram-positive bacteriahave a thick protein layer on their cell wall and stainpurple. Gram-negative bacteria have a thin protein layer on their cell wall and stainpink.

31. Identifying Bacteria & Archaea Other methods used to identify bacteria and archaea include size and shape, nutrition (i.e. aerobic or anaerobic processes), movement and genetic components. Biologists prefer techniques that rely on DNA comparisons.

32. Bacteria & Human Health B)Streptococcus pygonesis a Gram-positive bacterium that causes strep throat infections A) Clostridium botulinumis an anaerobic bacterium that can cause illness in humans C) Streptococcus mutansis a Gram positive bacterium that causes tooth decay

33. To Do List • Learning Check, p. 62 #7 – 12 • Review Questions, p. 66 # 2 – 9, 11 – 12

34. Eukaryotic evolution & diversity SBI 3U Section 2.3 pp.67- 71

35. Endosymbiosis The theory that says eukaryotic cells evolved from a prokaryotic cell engulfing one or more different prokaryotic cells. The engulfed cells survived and became an internal part of the engulfing cell

36. Chloroplasts & Mitochondria Theory suggests that mitochondria and chloroplasts were once small, free-living prokaryotes. When they were engulfed by other, larger cells, they remained intact and continued to function, benefitting the host cell. Endosymbiont  a cell that is engulfed by another cell in endosymbiosis Host cell  a cell that engulfs another cell in endosymbiosis

37. Evidence Similar features between chloroplasts, mitochondria and prokaryotes  Membranes  Ribosome's  Circular chromosome  Gene sequences  Divide by binary fission

38. Multicellularity Hypothesis  first multicellular organisms arose from colonies created by diving individual cells. Genes within these cells carried instructions to become specialized for different functions. Example: Some cell groups became specialized in absorbing nutrients, while others became specialized in gathering information from the surrounding environment

39. To Do List • Learning Check, p. 69 #13 – 17 • Review Questions, p. 71 # 1, 4, 6 – 9 • QUIZ COMING UP SOON on ‘MICROBIOLOGY’ • Assessment NEXT CLASS: Measles Immunization Graphing Activity (you need your textbook!) 

40. Protists: the unicellular eukaryotes SBI 3U Section 2.4 pp.72 - 78

41. Protists A eukaryotic organism, usually unicellular, that is not a fungus, plant or animal e.g. Amoeba

42. Characteristics  Eukaryotes  Most are unicellular  Most are aerobic (need O2)  Some are motile(able to move), some have pigments  Placed in this kingdom because they do not fit well in other kingdoms  Not very similar or closely related to one another

43. 3 Main Classes of Protists

44. Animal-like Protists • often called protozoans • Heterotrophs, live in aquatic environ. • 4 main classes • many species are parasites cause diseases Parasite  an organism that benefits by living in or on another organism

45. 1) Cercozoans • Cell membrane, no cell wall • Move and create different forms (change shape) • Live in water, mud and a few in living animal hosts Example: Amoeba Pseudopods (false feet) are temporary finger-like projections used for both feeding and movement

46. 2) Ciliates • Short, hair-like projections that cover the surface of the cell, called cilia • Cilia aids in movement and sweeping food particles into cell • Large, complex, some are parasites Example: Paramecium

47. 3) Flagellates • Have one or more flagella (long, hair-like projection that propels the cell) • Hard protective covering over membrane • Some parasitic, some mutualistic Example: Trichonympha A mutualistic relationship is a relationship where both organisms benefit

48. 4) Sporozoans • Entirely parasitic, taking nutrients from the animal host Example: Plasmodium vivax causes malaria in humans

49. Fungus-like Protists • Heterotrophs • Absorb nutrients from living organisms, dead organisms and wastes • Produce spores (reproductive structures) like fungi • Glide for motility Examples: Slime moulds, water moulds

50. Plant-like Protists • contain pigments like chlorophyll • photosynthetic • once classified as plants but lack leaves, stems and roots. • 3 main classes Examples: phytoplankton