Germs, Viruses + Fungi Unit: DYI bacteria model

Bacteria are a fascinating microbe with lots of special parts that each perform a specific job. Let’s create a larger model of a bacteria so we can examine the parts and learn what they each do.

What you need:
What to do:

Begin by cutting three equal-size pieces of cardboard (about 5-6 inches across), roughly in the shape of a kidney bean.

Stack and glue the pieces together to make a thicker piece.

Use the cardboard shape as a stencil to cut two similar pieces out of contrasting pieces of craft foam.

Cut out the middle of one of the pieces, leaving an edge, about half an inch thick.

Glue these over the top of the cardboard shape, like you:

The pink edge represents the cell wall, and the yellow foam represents the cytoplasm. Cut strips of another color of craft foam to the thickness of your model.

Hot glue these on to create an outer edge, which represents the bacteria’s capsule:

Using yarn, create a border inside the outer layer of foam. This represents the bacteria’s plasma membrane.

Glue a different color yarn into a bundle in the middle of your bacteria, which will represent the nucleoid (DNA). Next, glue beads in the middle as well to represent the ribosomes.

Use the same color yarn as you used to outline the center of the bacteria to create two small circles in the middle (the plasmids) and a sort of fringe around the bacteria (the pilus). Finally, cut a wiggly piece of foam (the same color as the outer edge) and glue it on to one end to represent the flagellum:

You may also wish to make a stand for your bacteria using scrap cardboard:

Here’s a brief outline of what each of these parts does:

  1. cell wall: The cell wall has multiple functions during bacterial growth, including maintaining bacterial cell integrity and shape as well as resisting internal turgor pressure. Furthermore, it must remain flexible to accommodate the remodeling that is required for cell division and growth. (source)
  2. capsule: An outer layer of polysaccharides that covers the cells of many different bacterial species. Capsules act as a sort of magic cloak, protecting bacteria from toxic compounds and desiccation and allowing them to adhere to surfaces and to escape the immune system of the host. (source)
  3. plasma membrane: The plasma membrane regulates the transport of materials entering and exiting the cell. (source)
  4. nucleoid (DNA): Responsible for controlling the bacteria’s activity and reproduction. (source)
  5. ribosomes: The site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins. (source)
  6. cytoplasm: The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out. (source)
  7. pilus (plural: pili): These surface structures provide bacteria with a link to their external environments by enabling them to interact with, and attach to, host cells, other surfaces or each other, or by providing a conduit for secretion. (source)
  8. plasmid: A plasmid is a small circular DNA molecule found in bacteria and some other microscopic organisms. Plasmids are physically separate from chromosomal DNA and replicate independently. (source) They act as delivery vehicles, or vectors, to introduce foreign DNA into bacteria. (source)
  9. flagellum: Bacterial flagella are long hairy structures that help in their ability to move from one place to another. (source)

For additional help, you can watch this video demonstrating how to build the bacteria cell.

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Published by The Learn + Live Letter

The Learn + Live Letter is a play- and project-based homeschool curriculum for children ages 3-12.