Reproduction of Microorganisms

1. Reproduction of Microorganisms SaraAustin • Microorganisms are literally “microscopic organisms”, which can only be seen with a microscope. • They include bacteria, fungi and viruses. • Helpful microorganisms are used in industry and biotechnology, but • Harmful microorganisms cause many human diseases • Understanding their reproduction is essential to interacting safely • We control bacteria to help us, and to try to prevent them from harming us

2. Teaching Strategies • The Hook: the Five-Second Rule –is it true? • Two college students examined food dropped on the floor of a cafeteria for various lengths of time, and measured bacterial growth. • http://abcnews.go.com/Video/playerIndex?id=3269384 • (note 12 second commercial plays first) • Stop the video once the study is described, and ask for predictions from students as to the outcome.

3. Curriculum Correlation This concept is part of the SBI3C course, within the Microbiology strand • Three types of microorganisms are examined: bacteria, viruses, and fungi • These microorganisms have different types of reproduction - diagrams and life cycle graphics are essential

4. Reproduction in Microorganisms Ministry Curriculum Expectation • C3.4 By the end of the course, students will be able to explain the different methods of reproduction in various types of bacteria, viruses, and fungi

5. Overview - Microorganism Reproduction • Bacteria: Binary Fission Conjugation • Viruses: Lysogenic cycle Lytic cycle Retroviruses • Fungi: Sporulation Sexual & Asexual

6. Overview: Bacterial ReproductionBinary Fission • Binary Fission: the single strand of DNA replicates, resulting in identical genetic material being transferred to each new cell. Following replication of the genetic material, the bacterium produces a cross wall, dividing the cell in to two identical bacteria, which may separate or remain attached. • Animation of Binary Fission: • http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::500::500::/sites/dl/free/0073375225/594358/BinaryFission.swf::BinaryFission • Actual film of bacteria dividing by binary fission: • http://cellsalive.com/qtmovs/ecoli_mov.htm

7. Overview: Bacterial ReproductionConjugation • 1- Donor cell produces pilus (cytoplasmic projection) • 2- Pilus attaches to recipient cell, brings the two cells together • 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell • 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili. Both cells are now viable donors. • From http://parts.mit.edu/igem07/index.php/Boston_University/Conjugation

8. Overview: Viral Reproduction • Viral Replication occurs through a Lytic cycle. • Some viruses are dormant for some time, and maintain a Lysogenic cycle until activated to enter the Lytic cycle

9. Overview: Viral Reproduction • LYTIC CYCLE: • Viral genetic material injected into host cell and takes over machinery to produce parts of future viruses. Parts are assembled and the cell explodes (lysis), releasing more harmful viruses. “Virulent” viruses undergo a lytic cycle.

10. Overview: Viral ReproductionLytic Cycle Steps …follow the moving yellow oval as the steps are highlighted • Attachment and entrance • Synthesis of protein and nucleic acid • Assembly of units • Release of new virus particles

11. Overview: Viral Reproduction • LYSOGENIC CYCLE: • Viral genetic material remains dormant, replicated with the host cell DNA each time the cell divides. • “Temperate” viruses undergo a lysogenic cycle. At some point, the lytic cycle is triggered.

12. Overview: Viral Reproduction • RETROVIRUSEScontain RNA as their genetic material. The virus contains reverse transcriptase, which it uses to make DNA from an RNA template (this never occurs in cellular organisms). The cell then follows the directions in the new DNA code, and the lytic cycle is triggered. • Teaching Note: • It is worth reviewing the functions of DNA and RNA. Viruses are classified according to their genetic molecule (DNA or RNA), and whether the nucleic acid is single-stranded or double-stranded.

13. Overview: Viral ReproductionWeb-based Animations • Lytic Cycle animation: • http://www.courses.fas.harvard.edu/~biotext/animations/lyticcycle.html • Lysogenic Cycle animation: • http://www.courses.fas.harvard.edu/~biotext/animations/lysogeny.html HIV life cycle animation: http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120088/micro41.swf::HIV%20Replication

14. Overview: Fungal Reproduction • Fungi reproduce both asexually and sexually but always produce spores as reproductive cells. Spores are usually dispersed by air currents, and germinate in suitable conditions. Animation of Fungal Reproduction http://bcs.whfreeman.com/thelifewire/content/chp31/31020.html

15. Overview: Fungal Reproduction • Haploid hyphae, found below the soil, fuse to begin reproduction. • The hyphae enlarge, break through the soil as white spheres called buttons • Buttons grow and mature, forming a stalk and a spherical cap • Within the cap, gills form, consisting of many tangled, modified hyphae. • Specialized extensions from gills containing two haploid nuclei of different parents fuse, then undergo meiosis to produce four haploid spores, which are released over several days

16. Prior Knowledge • Students will have some basic concepts about microorganisms from previous grades: the role of microorganisms in food chains and ecosystems, the immune system; the exchange of genetic information; bacteria, plant-like and animal-like protists, fungi, and viruses. • Skills: Students should have some basic microscope skills and be able to recognize eukaryotic cells (plant and animal) by their organelles.

17. Lesson Scope and Sequence • In many texts, the Microbiology strand is organized by type of microorganism, with reproduction integrated (e.g., Nelson College Prep Biology 11). • This lesson scope and sequence offers a means to teach all the reproductive methods at once, to compare them, and to relate them to technology and society. • Students can organize a comparison of the various mechanisms of reproduction

18. Lesson Plan

19. Demonstration • Build a dung chamber as an attention grabber for the content about Fungi: • Go for a hike and find some dung from a vegetarian animal (rabbit or deer pellets) • Put the dung in a petrie dish with a damp paper towel or sprinkle with water • Start about four days before this lesson so that students can see some real-life examples of the fungi as they proceed through the section content

20. Demonstration • Build a dung chamber as an attention grabber for the content about Fungi: • Within a few days moulds will begin to appear on the specimen. Most beginners are unprepared for the extremely small size of many moulds and tend to overlook them completely. Invariably students using moist chambers for the first time complain that nothing is growing on their specimens, only to have an instructor point out at least half a dozen different moulds! Be sure to examine the material with a magnification of at least 15-20 timesand with good bright illumination. Illumination is especially important and should be focused on the area of the specimen that is under examination. • From http://website.nbm-mnb.ca/mycologywebpages/Moulds/Isolation.html

21. Other Demonstrations Mouldy Bread Demo: Keep mouldy bread sealed in clear container – do not open! From Nelson Biology 11 College Preparation text p.141, eacher’s Resource p.247 • Mushroom Dissection Lab/Demo • www.biologyjunction.com/Mushroom%20Dissection%20Lab.doc Yeast Fermentation Demo http://cccmkc.edu.hk/~sbj-biology/CERT%20BIO/Energetics/Respiration/Yeast%27s%20fermentation%20%28demo%29.htm

22. Peer Activity • Student Exploration: Virus Lytic Cycle • http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=448 Release a lytic virus in a group of cells and observe how cells are infected over time and eventually destroyed. Data related to the number of healthy cells, infected cells, and viruses can be recorded over time to determine the time required for the virus to mature within a cell.

23. Handout • Students will receive a set of handouts as they progress through the lessons, briefly outlining the various steps of the reproductive cycles of Viruses, Fungi and Bacteria. • A brief overview handout is available in the summary document.

24. Suggested Labs • Examination of Lichen • http://lichens.science.oregonstate.edu/lab/LABMATERIALS.htm • Mushroom Dissection Lab • www.biologyjunction.com/Mushroom%20Dissection%20Lab.doc

25. Websites for Lesson Planning • www.who.int/csr/don/en/ • http://science.nelson.com/0176265252/teachweblinks_ch02.html • http://serendip.brynmawr.edu/sci_edu/waldron/ • http://www.lessonplanet.com/lesson-plans/microorganisms • http://www.tes.co.uk/taxonomySearchResults.aspx?keywords=micro-organisms • http://serc.carleton.edu/microbelife/index.html

26. Potential Areas of Difficulty • Students may think there were no effective treatments for diseases because they were undiagnosed in the past – but anti-infective agents been used for thousands of years. The Chinese recognized that mouldy soybean curd was effective against skin infections. Scabies was treated with sulfur. Mercury was used to treat syphilis. • Viruses represent an example of the “which came first” riddle. Viruses seem to be a stage between abiotic and biotic organisms, yet they must have appeared after cells, as viruses cannot reproduce on their own. A decimal numbering system is also used for viral classification (e.g., H1N1). It was decided years ago that viruses would not use Latinized binomial terms. • Students may think that mushrooms growing on trees only benefit nutritionally – but in fact, mushrooms can use trees to gain a better, sunnier position in a shady environment like a rain forest. Sometimes fungi climb tress and vines to release their spores from as high a position as possible. From Nelson Biology 11 College Preparation, Teacher’s Guide, Unit 2 Section Support, pp 165-266

27. Potential Areas of Difficulty • Gene therapy diagrams look straightforward and reliable, but gene therapy is still experimental and controversial. Some stunning success stories, and some devastating failures. Pathogenic organisms and the diseases they cause do not remain static. The incidence of new of changing diseases caused by bacteria, viruses, and protozoa are increasing. If moulds are so ubiquitous, why are we not affected by all of them? Moulds are opportunistic organisms: they infect humans at sites of lesions, or when immunodeficient, or during serious diseases such as cancer or diabetes. From Nelson Biology 11 College Preparation, Teacher’s Guide, Unit 2 Section Support, pp 165-266

28. Visual Aids • The Hook: the Five-Second Rule –is it true? • http://abcnews.go.com/Video/playerIndex?id=3269384 http://www.microbeworld.org/ These fun soft microorganisms are sure to be popular with students and lead to good discussions and inquiries. Viral Geometry and Structural Diversity film The geometric structures of viruses are beautiful and can be used, along with genomic information, to identify them. (3 minutes 22 seconds) http://www.hhmi.org/biointeractive/disease/viral_diversity.html Prepared Microscope Slides of Microorganisms Available from science suppliers such as Boreal

29. Safety Considerations • Students should wash hands before handling (to prevent contamination) and after handling (for safety) all organic material. • Proper microscope procedures should be reviewed. • Mouldy bread should remain covered when examined by students. • Mouldy dung should be disposed of by the teacher, wrapped, with care. • Internet use carries its own safety hazards. Students must be supervised to ensure they remain on-task on lesson-focused sites.

30. Evaluation Instruments:Comparison/Explanation • Students create a comparison of reproductive strategies of bacteria (binary fission), fungi (spores, nuclear fusion), and viruses (lysogenic and lytic cycles). • Students develop this by examining teacher-provided charts/posters/diagrams/videos (and do online research as needed) illustrating the life cycle and reproductive strategy of a representative from each of bacteria, fungi, and viruses.

31. Evaluation Instruments:Comparison/Explanation • Students choose the form of this comparison, as long as critical information is present: a song, a poem, a letter, a set of resumes, a business plan, a poster, an advertisement, a graphic organizer, a commentated video/podcast, a script. The rubric for all products is the same: students are being evaluated on their ability to explain the different methods of reproduction in various types of bacteria, viruses, and fungi. Students and teachers can together develop a rubric to evaluate the products.

32. Evaluation Instruments:RAFT Activity (STSE) Choose one:

33. Practical and Societal Implications: Microorganisms and Human Disease • Examples of familiar human diseases include: • Bacteria: salmonella, tetanus, typhoid, cholera, gangrene, bacterial dysentery, diphtheria, tuberculosis, bubonic plague, meningococcal meningitis, pneumococcal pneumonia • Viruses: rabies, influenza (flu), measles, mumps, polio, rubella (german measles), chicken pox, colds, warts, cold sores • Fungi: athlete's foot, ringworm Potential Student Research Projects Epidemics in the news: AIDS/HIV,SARS, Bird Flu, Influenza, Norwalk virus, West Nile virus, Malaria • www.who.org • Communicable disease surveillance site • http://www.phac-aspc.gc.ca/id-mi/index-eng.php • Canadian Public Health Agency Harmful microorganisms are the cause of disease and decay that is not due to structural problems or mutations in humans. Many microorganisms also cause disease and decay in crops and farm animals.

34. Practical and Societal Implications:Biotechnology • Related Possible Activities: • Act 5.6.1 Students view a video or visit a local factory highlighting the importance of microbes in development of consumer products - e.g., edible fungi, bacteria converting milk to yoghurt and cheese, moulds adding flavour to Roquefort and Camembert cheeses, antibiotics (zones of inhibition on agar), methanogens to create fuels from manure. • From SBI3C Course Profile, www.curriculum.org • Industry: • Preventing microorganism growth in food handling facilities (Maple Leaf meats - contamination) • Hormone production, Food production • Waste management

35. Practical and Societal Implications:Biotechnology • Biotechnology: bacterial vectors are used extensively for gene transfer • Viral vectors for medical therapies • Probiotics: to replenish gastrointestinal tract Act 5.6.2 Cooperative Learning - Using teacher-provided resources, students investigate the uses and development of microbes in the areas of biotechnology and genetic engineering. This may include bacteria as vectors for cloning and as hosts for protein production (insulin and growth hormone), retroviruses as vectors for gene therapy (ADA and SCID), research on viroids, large scale use of fungicides and pesticides on diversity using a variety of electronic and print media. Students may present their findings. From SBI3C Course Profile, www.curriculum.org

36. Internet Sites • Communicable disease surveillance site • www.who.org • www.who.int/csr/don/en/ • Canadian Public Health Agency • http://www.phac-aspc.gc.ca/id-mi/index-eng.php • Viral Geometry and Structural Diversity film • The geometric structures of viruses are beautiful and can be used, along with genomic information, to identify them. • (3 minutes 22 seconds) • http://www.hhmi.org/biointeractive/disease/viral_diversity.html • http://www.pbs.org/opb/intimatestrangers/ • Animation of Binary Fission: • http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::500::500::/sites/dl/free/0073375225/594358/BinaryFission.swf::BinaryFission • Actual film of bacteria dividing by binary fission: • http://cellsalive.com/qtmovs/ecoli_mov.htm http://www.peteducation.com/article.cfm?c=18+1803&aid=2956 http://serendip.brynmawr.edu/sci_edu/waldron/ Gizmo: Viral Lytic Cycle http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=448

37. Suggestions for Other Student Labs • Is Yeast Alive? • Students evaluate whether the little brown grains of yeast obtained from the grocery store are alive by testing for metabolism and growth. • Alcoholic Fermentation in Yeast • Students learn about the basics of aerobic cellular respiration and alcoholic fermentation and design and carry out experiments to test how variables such as sugar concentration influence the rate of alcoholic fermentation in yeast.  In an optional extension activity students can use their yeast mixture to make a small roll of bread. • Moldy Jell-O • Students design experiments to determine how substrate and environmental conditions influence growth of common molds. • All can be found with Student Handouts and Teacher Preparation notes at: • http://serendip.brynmawr.edu/sci_edu/waldron/

38. Accommodations • Ensure that peer helpers are available when students are working in small groups. • Provide handout sheets with specific skill instructions. • Help students create data charts into which they record information. • Advise special education staff in advance when students are working on major assignments. • Record key words on the board when students are expected to make their own notes. • Allow students to report verbally to a scribe (teacher or student) who can then help in note making. • Permit students a wide range of options for recording and reporting their work to utilize student strengths (e.g., drawings, diagrams, flow charts, concept maps). • Timelines may need to be extended to give students more time to process language and put their thoughts into words. • Where an activity requires reading, give it in advance to students or provide a selection of materials at different reading levels. From SBI3C Course Profile, www.curriculum.org

39. ESL/ELL Accommodations • Where an activity requires reading, give it in advance to students. • Have the teacher-librarian identify resources with appropriate reading level when research is required. • Advise ESL/ESD staff in advance when significant written work is required. • Permit the use of a translation dictionary on assessments. • Have students keep a science dictionary of terms using pictures and first language words. • Provide additional time on assessments for dictionary use and processing language. From SBI3C Course Profile, www.curriculum.org