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BacteriaBacteria

  • Subject:
  • |
  • Grade(s): 9-12
  • |
  • Duration: Two class periods

Lesson Plan Sections

Objectives


Students will understand the following:
1. Reproduction in bacteria may occur asexually by a form of cell division called fission or sexually by a transfer of genetic material from a donor bacterium to a recipient.
2. Bacterial reproduction occurs in a number of stages.
3. Bacterial reproduction differs from mitotic reproduction in a single human cell.

Materials


For this lesson, you will need:
Research materials on bacteria and bacterial reproduction
Computer with Internet access
Clay for constructing models

Procedures


1. Review with your students what they have learned about cell reproduction, concentrating on reproduction in bacteria.
2. Using print materials and the Internet, students should discover that reproduction in bacteria may occur asexually by a form of cell division called fission or sexually by a transfer of genetic material from a donor bacterium to a recipient.
3. Instruct students to take careful notes and make diagrams as they do their research.
4. In class, encourage students to share their research findings.
5. Have each student construct a clay model of one of the bacterial reproduction processes he or she has learned about. Each model should be labeled and accompanied by a paragraph identifying and describing the process illustrated by the model.
6. More advanced students can extend the project by writing paragraphs comparing and contrasting reproduction in bacteria with mitotic reproduction in a single human cell.

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Adaptations


Rather than having students do their own research on reproduction in bacteria, explain the process to them, using simple terms and diagrams.

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Discussion Questions


1. Discuss ways that life on Earth depends upon bacteria.
2. Compare bacteria to other single-celled organisms. How do they differ? How do they compare to viruses?
3. Discuss the beneficial uses of bacterial toxins in medicine.
4. Explain how bacteria change and adapt to new environments.
5. Discuss how the widespread use of antibiotics in society has contributed to problems in daycare centers and hospitals.
6. Explain the importance of genetic research in understanding microorganisms.
7. Discuss how, in your daily living, you can protect yourself and others from contamination by pathogenic microorganisms.
8. Discuss how microorganisms are economically important to humans.

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Evaluation


You can evaluate your students on their models and paragraphs using the following three-point rubric:
 
Three points: model accurately constructed and clearly labeled; paragraph accurate, complete, clearly written
 
Two points: model adequately constructed and labeled; paragraph accurate but incomplete and lacking in clarity
 
One point: model inadequate and insufficiently labeled; paragraph incomplete, lacking in clarity, and containing inaccuracies
 
You can ask your students to contribute to the assessment rubric by determining what a viewer should be able to learn from a model.

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Extensions


Bacteria in the News
Some interesting bacteria in the news are leprosy, Lyme disease, and Pfiesteria piscicida —the toxic organism responsible for killing fish along the Atlantic coast. Have students investigate these or choose another infectious disease of an animal or plant. Students' investigations should cover the following: history, symptoms, pathogen, treatment, epidemiology (disease control). Students should include as many media sources as possible.

Oil Spill Lunch
Bioremediation is a process by which certain bacteria are used to degrade hazardous substances in the environment. Invite students to research the process of bioremediation as it has been applied to the treatment of oil spills. How does this natural process work? What are the growth requirements for the bacteria used? What conditions limit their population growth? What problems may arise if these populations of bacteria increase in the environment? What guidelines has the Environmental Protection Agency established for this practice? Have students present their case studies to the class.

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Suggested Readings


Virus X: Tracking the New Killer Plagues out of the Present and into the Future
Frank Ryan, M.D. Little, Brown and Company, 1997.
Join the author as he describes today's dangerous outbreaks of Hantavirus, Ebola, Marburg, "mad cow," and the flesh-eating diseases, and then go into research laboratories and hospitals to see scientists and doctors who are trying to understand and contain these catastrophic epidemics.

Man and Microbes: Disease and Plagues in History and Modern Times
Arno Karlen. Jeremy P. Tarcher/Putnam Book, 1995.
Modern life has altered the environment, changed the relationship between humans and microbes, and generated new diseases. The author uses case studies and stories of medical detection to show the causes of these diseases and how scientists and doctors are working together to conquer this global crisis.

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Links


Do You Have What It Takes to Fight Germs?
Current medical information on fighting germs and the current antibacterial soap business.

The Microbe Zoo
A digital learning center for microbial ecology that would appeal to all ages.

Bugs in the News
Award winning site with well written articles and links in viruses and bacteria.

Cells Alive
State of the Art site on cells that covers all aspects of bacteria and viruses. Appealing to all ages.

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Vocabulary


Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    mutate
Definition: To change either the physical relation of chromosomes or the genetic sequence in an organism.
Context: Bacteria do what they do best—mutate—changing to adapt to new conditions in their environment.

speaker    microorganism
Definition: An organism of microscopic or ultramicroscopic size.
Context: We are destined to always live with microorganisms—from the friendly bacteria that help us digest food to the undesirable pathogens that make us sick.

speaker    pathogen
Definition: A specific causative agent of disease like a bacterium or virus.
Context: Pathogens, such as salmonella and streptococcus, cause untold human misery.

speaker    plasmid
Definition: An extrachromosomal ring of bacterial DNA that replicates autonomously.
Context: Plasmids hold genetic information.

speaker    enzyme
Definition: Any of numerous complex proteins that are produced by living cells and catalyze specific biochemical reactions at body temperatures.
Context: In order for a microbe to consume food from its environment, it has to make enzymes, which break down the food into usable molecules.

speaker    culture medium
Definition: A nutrient system for the artificial cultivation of cells or organisms, especially bacteria.
Context: There are many bacteria that can't be grown on culture media.

speaker    microbiology
Definition: A branch of biology dealing especially with microscopic forms of life.
Context: With the emergence of new technologies and new understanding about the functions of microorganisms, experts say this is the beginning age of microbiology.

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Standards


This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level: 6-8
Subject area: technology
Standard:
Understands the relationships among science, technology, society, and the individual.
Benchmarks:
Knows ways in which technology has influenced the course of history (e.g., revolutions in agriculture, manufacturing, sanitation, medicine, warfare, transportation, information processing, communication).

Grade level: 6-8
Subject area: geography
Standard:
Understands the characteristics of ecosystems on Earth's surface.
Benchmarks:
Knows the effects of biological magnification in ecosystems (e.g., the increase in contaminants in succeeding levels of the food chain and the consequences for different life forms).

Grade level: 6-8
Subject area: life science
Standard:
Understands how species depend on one another and on the environment for survival.
Benchmarks:
Knows ways in which species interact and depend on one another in an ecosystem (e.g., producer/consumer, predator/prey, parasite/host, relationships that are mutually beneficial or competitive).

Grade level: 6-8
Subject area: life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that hereditary information is contained in genes (located in the chromosomes of each cell), each of which carries a single unit of information; an inherited trait of an individual can be determined by either one or many genes, and a single gene can influence more than one trait.

Grade level: 6-8
Subject area: life science
Standard:
Knows the general structure and function of cells in organisms.
Benchmarks:
Knows that disease in organisms can be caused by intrinsic failures of the system or infection by other organisms.

Grade level: 9-12
Subject area: life science
Standard:
Knows about the diversity and unity that characterize life.
Benchmarks:
Knows how variation of organisms within a species increases the chance of survival of the species, and how the great diversity of species on Earth increases the chance of survival of life in the event of major global changes.

Grade level: 9-12
Subject area: life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows ways in which genes (segments of DNA molecules) may be altered and combined to create genetic variation within a species (e.g., recombination of genetic material; mutations; errors in copying genetic material during cell division).

Grade level: 9-12
Subject area: life science
Standard:
Knows the general structure and function of cells in organisms.
Benchmarks:
Understands the chemical reactions involved in cell functions (e.g., food molecules taken into cells are broken down to provide the chemical constituents needed to synthesize other molecules; enzymes facilitate the breakdown and synthesis of molecules).

Grade level: 9-12
Subject area: life science
Standard:
Understands the basic concept of evolution of the species.
Benchmarks:
Knows that natural selection leads to organisms that are well suited for survival in particular environments, so that when an environment changes, some inherited characteristics become more or less advantageous or neutral, and chance alone can result in characteristics having no survival or reproductive value.

Grade level: 9-12
Subject area: technology
Standard:
Understands the interactions of science, technology, and society.
Benchmarks:
Knows that technological knowledge is often not made public because of patents and the financial potential of the idea or invention; scientific knowledge is made public through presentations at professional meetings and publications in scientific journals.

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Credit


Lisa Lyle Wu, science teacher, Thomas Jefferson High School for Science and Technology, Alexandria, Virginia.

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