Lesson Plan

Prokaryotes: The Simplest Forms of Life


In this lesson, students will learn that prokaryotes are the simplest cells, yet show all the characteristics found in living things. Students will observe prokaryotic cells under a microscope and hypothesize about their structures. Students will:

  • mount, stain, and observe bacteria cells under a microscope.

  • make a model of a typical prokaryotic cell and explain how each part functions within the cell.

  • relate the structure and function of prokaryotic cells to the common characteristics of living things.

Essential Questions


  • Archaea: Unicellular prokaryotes that have cell walls that do not contain peptidoglycan.

  • Archaebacteria: Kingdom of unicellular prokaryotes whose cell walls do not contain peptidoglycan.

  • Bacteria: The most abundant and most studied group of prokaryotes.

  • Capsule: Including the slime-layer, made of polysaccharides (or proteins) that aid in attachment and protects the cell from dehydration and being engulfed or digested by enzymes. It also sometimes stores nutrients.

  • Cell Wall: Formed from peptidoglycan (polysaccharide and protein), protects the cell from osmotic lysis (taking in too much water and bursting) and gives the cell shape.

  • Cytoplasm: Mostly made of water, this is where all internal structures are found and where all chemical reactions take place.

  • Flagellum: (plural, flagella) A long whip-like attachment made of protein that is used for movement. It originates in the cytoplasm, just below the plasma membrane. Prokaryotes may have one, two, or many flagella.

  • Nucleoid: The central portion of the cytoplasm that contains the circular genetic material contained in the plasma membrane. It is not separated from the cytoplasm by a membrane.

  • Pilus: (plural, pili) A hollow protrusion made of protein. Pili are part of the plasma membrane and aid in attachment to other cells or surfaces, and in sensing the environment. The sex pilus allows the transfer of genetic material during conjugation. Also called fimbria.

  • Plasma Membrane: Phospholipid bilayer imbedded with many proteins that are used in the transport of ions, nutrients, and wastes across the membrane. Also called cell membrane.

  • Plasmid: Small circular double-stranded genetic material. They are transferred to another bacterium during conjugation. Some plasmids carry genes for antibiotic resistance or form toxins.

  • Prokaryote: Single-celled organism that does not contain a nucleus or membrane-bound organelles.

  • Ribosomes: Small inclusions that translate the genetic code into protein.

  • Unicellular: Organisms made up of a single cell.


2 ½ hours/3 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.


  • beaker

  • distilled water

  • eye dropper

  • methylene blue

  • toothpick

  • light microscopes (one/group), or high-powered light microscopes (if available)

  • slide and slip cover (one/group)

  • prepared slides of prokaryotic cells (if available)

  • non-latex gloves

  • goggles

  • empty water/soda bottles (one/group)

  • resealable plastic bags, sandwich bags, or large non-latex balloons (one/group)

  • yarn, ribbon, and string

  • beads, seeds, and beans

  • straws or coffee stirrers

  • toothpicks

  • glue or hot glue

Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

  • beaker

  • distilled water

  • eye dropper

  • methylene blue

  • toothpick

  • light microscopes (one/group), or high-powered light microscopes (if available)

  • slide and slip cover (one/group)

  • prepared slides of prokaryotic cells (if available)

  • non-latex gloves

  • goggles

  • empty water/soda bottles (one/group)

  • resealable plastic bags, sandwich bags, or large non-latex balloons (one/group)

  • yarn, ribbon, and string

  • beads, seeds, and beans

  • straws or coffee stirrers

  • toothpicks

  • glue or hot glue

Formative Assessment

  • View
    • Monitor students throughout microscope activity, providing feedback on proper culture set-up and antiseptic techniques.

    • Generally assess understanding through group work and lecture.

    • Collect lab sheets, worksheets, and models for individual assessment.

    • Elicit responses that relate structures to the processes and characteristics common to all organisms throughout lecture to assess general understanding of prokaryotic structures and functions.

    • Join in on the gallery walk and use the Gallery Walk Questions worksheet to assess it.

Suggested Instructional Supports

  • View
    Active Engagement, Modeling, Explicit Instruction

    This lesson focus on the structure and function of prokaryotic cells. Structures found in bacteria represent those found in a typical prokaryotic cell. Students may be unfamiliar with the terms used in the lesson, so investing time in vocabulary attainment is necessary. Students will be evaluated on their observations in class and participation in the activities.


    Under the microscope, students will observe common bacteria found in yogurt, often referred to as “probiotics.” Their internal and external structures cannot be seen, so students will continue with an inquiry lesson using functions to determine the structures.


    Students will prepare their own slides to observe bacteria under the microscope. They will also work in groups to build a model of a prokaryote in an inquiry lesson.


    After the inquiry lesson, students will view other students’ models and rethink how they incorporated the structures on their model. They will revise their understanding of those structures as they relate the characteristics of living things to the structures found in a prokaryotic cell.


    Formative assessment is used throughout the lesson. You will observe student behavior in the lab and group activities, ask questions to check for understanding, and collect student work for individual assessment.


    Observing cells, building models, and doing a foldable activity provide students practice with vocabulary. An extension is given to accommodate students that go beyond the standards.


    The lesson is organized so that students will move from the concrete, observing bacteria under the microscope, to the more abstract themes of biology, how structure relates to function and the characteristics of living things.

Instructional Procedures

  • View

    Day 1

    Safety Precautions

    • It is helpful to go through the lab yourself before conducting the lesson.

    • Tell students that hot glue left in unintended places will result in a lower grade.

    Students will be studying the structures of prokaryotic cells and how these tiny organisms carry out all the functions of living things. This is not a classification lesson, so Archaebacteria and Eubacteria should not be discussed at this point.

    Begin the lesson by telling students that on May 20, 2010, scientists at the J. Craig Venter Institute in Maryland created the first synthetic (man-made) organism. Dr. Craig Venter hopes that Synthia, M. mycoides JCVI-syn1.0 (nicknamed “Synthia,”) can be programmed to make vaccines or biofuels in the future. Ask students: “How did Venter know Synthia were life forms?” They exhibit all the characteristics of living things. They are cells, which obtain and use energy, reproduce, maintain homeostasis, grow and develop, respond to stimuli and are adapted to their environment. Venter did not claim they were alive until they reproduced; however, the cells did exhibit these traits, except perhaps adaptations because they were grown in a laboratory.


    Tell students that Synthia is a prokaryote, the same type of organism they will observe. However, instead of observing the newest prokaryote, they will observe two of the oldest prokaryotes used by man, Streptococcus thermophilus and Lactobacillus bulgaricus, both of which are found in yogurt. Show students the following microscopic images (S-B-3-1_Prokaryote Pictures.doc).

    Sources: http://www.oley.org/images/Lactobacillus.jpg




    Hand out copies of the What Do Prokaryotes Look Like? worksheet (S-B-3-1_What Do Prokaryotes Look Like and KEY.doc).

    Demonstrate how to make a wet mount slide and stain the bacteria before allowing students to begin Activity 1. Refer to the following Web sites for instructions on preparing a wet mount slide:

    • Great Scopes
    • Microbus

    Activity 1: Observing Bacteria on a Wet Mount Slide

    Have students work in small groups of two or three. While students are working on the activity:

    • Ask students about their lab techniques and their observations.

    • Make sure the slides are very clean. It is difficult for students to tell the difference between dust and prokaryotic cells.

    • Make sure their drawings include magnification and the size is appropriately scaled to their field of vision.

    • After the activity, have students clean their slides and wash their hands.

    Bacteria are tiny and students may not be able to differentiate between the Streptococcus (spherical shape) and the Lactobacillus (rod-shaped). If available, you may want students to observe the cells with an oil emersion lens (1000X), or have a microscope set up in the classroom so that students can see the cells with the increased magnification.

    Discuss the students’ observations. Lead students to comment on the small size of the cells and how the cells did not have a nucleus. Tell students that prokaryotes are the simplest forms of life: “In fact, the name prokaryote means before nucleus (pro = before; karyote = kernel or nucleus). Prokaryotes are unicellular organisms that lack a membrane bound nucleus. They lack many of the structures that are found in the cells of plants and animals. Nevertheless, prokaryotes are a very successful group of organisms. They have exploited more habitats than any other group, including deep ocean vents, the gut of cows, and your skin.” On the board, write down some places bacteria live. Discuss “good” versus “bad” bacteria, and how they can both help and harm people.

    Day 2

    Note: If possible, before the lesson, obtain a copy of Bill Bryson’s, “A Short History of Nearly Everything” (see Related Resources).

    Read the first two paragraphs of Bill Bryson’s, “A Short History of Nearly Everything,” Chapter 20: Small World, p. 302, or have students read the first two pages of the essay. If you do not have a copy of the book, explain that bacteria are prokaryotes and their success has to do with their structure.

    Activity 2: Modeling Prokaryotes

    Before this activity, make a model or find a diagram of a typical prokaryotic cell to use for discussion after the activity (S-B-3-1_Prokaryote Cell.docx).

    Students will build and present a three-dimensional model of a typical prokaryote cell, knowing only names of the structures and their functions. Have students form groups of two or three, give students the Parts of a Prokaryote Worksheet (S-B-3-1_Parts of a Prokaryote Worksheet.doc) that describes the functions of each structure and have supplies available. Students are not allowed to look in the book or on the Internet to find pictures or diagrams of prokaryotes.

    Write the materials and steps for building their model on the board and have students write the steps on the handout.

    Step 1
    Discuss the structures and functions of the prokaryotic cell with your group and hypothesize where the structures are located. List the structures that belong at that location.

    Within the membrane

    Outside the membrane


    Step 2

    Make a sketch of your model. Label each part and what material you will use to represent it. Remind students that living things show order; structures are not haphazardly attached to the cell.

    Step 3

    Build and label the parts of the cell model. CAUTION: Hot glue is HOT and can burn the skin! If you choose to use hot glue, have the group show you a sketch before you give them the hot glue gun. Avoid using clay or water. Clay tends to end up on the bottom of shoes and students rarely make water-tight cell models.


    1. Which of these structures help bacteria to survive in harsh conditions, such as heat, and in the presence of disinfectants and antibiotics?

    2. What happens when bacteria become resistant to antibiotics?

    3. How do human activities increase our resistance to antibiotics?

    4. How can we keep this from happening as often?

    5. If you stop taking an antibiotic before you are finished with the prescribed regimen, can it affect others as well as you?

    Day 3

    Have students look at other groups’ cells in a gallery walk (S-B-3-1_Prokaryote Model Gallery Walk and KEY.doc). Post questions with each model. Have students record their responses to the questions posted at every model but their own. As you circulate amongst students during the gallery walk, listen for misinterpretations of the functions (e.g., the sex pilus is not for reproduction). Have students summarize their findings in their science journals or notebooks.

    Show students the teacher model or the diagram of a prokaryote and discuss differences that they observe. Discuss any misconceptions students revealed during the activity. For instance, the sex pilus is for the exchange of genetic material; it does not mean that the cell with the sex pilus is “male.” Also, some students may have put the cell wall inside the cell membrane because it is used for support (the human skeleton is used for support inside the body). Explain that the cell wall controls how much water enters the cell and it could not do that from inside the membrane. Finally, since prokaryotes are unicellular, all characteristics common to organisms are also the cell properties. Each part of the prokaryote cell helps to carry on the processes of living things. Ask how each prokaryotic structure relates to a biological characteristic. Have students complete the Prokaryotic Cell Structures and Functions Chart (S-B-3-1_Prokaryotic Cell Structures and Functions Chart and KEY.doc).


    • Students who may be going beyond the standards can investigate the optimum growing conditions (i.e., temperature, light) for bacteria collected from the soil, or lima bean water. Students will need several agar plates, one to grow their first culture and several for the test. Students should use proper antiseptic techniques while conducting this research. Have students share their findings with the class.

    • Students who may be going beyond the standards can answer the Extension Questions for the Modeling Prokaryotes activity on Day 2.

    • Students who may require more practice with the standards can label a diagram of the prokaryote cell with vocabulary tabs to help learn the names and functions of structures (S-B-3-1_Prokaryotic Review.doc).

Related Instructional Videos

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DRAFT 11/19/2010
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