Parts of Bacteria
4 Minutes
Bacteria structure and nutrition for kids: learn about bacterial cell parts, prokaryotes, and how bacteria feed. A science lesson in English.
- Size of single-celled bacteria and what cell walls do
- Parts like flagella, cytoplasm, ribosomes, plasmids, and nucleoids
- How bacteria feed using photosynthesis, chemicals, or hosts
What this lesson teaches
Bacteria are single-celled microorganisms measuring between one and five micrometers in size that live almost everywhere in the world. They are classified as prokaryotes because their cell structure contains a nucleoid without a surrounding membrane rather than a true nucleus.
Where bacteria live and how small they are
Bacteria are present in every environment, including the air around us, the food we consume, and inside animals and humans. While humans are large because our bodies are built from many cells, bacteria are made of only one cell. Because a micrometer is vastly smaller than a millimeter or centimeter, these single-celled organisms are extremely tiny.
Cell wall, flagella, and cytoplasm
- The cell wall surrounds the bacterium like a compound wall around a house, controlling which substances can enter and leave.
- The flagella is a tail-like part that bacteria use to move around, functioning much like legs do for humans.
- The cytoplasm is a gel-like fluid inside the cell wall that houses the internal working parts of the bacterium.
- The ribosome is a type of protein structure inside the cytoplasm that repairs the cell if it becomes damaged.
Plasmids and the nucleoid
Human cells contain a nucleus wrapped in a protective membrane, but a bacterium has a nucleoid with no surrounding membrane. Organisms that have a nucleoid rather than a membrane-bound nucleus are called prokaryotes, meaning all bacteria are prokaryotes. Bacteria also have circular rings of extrachromosomal DNA called plasmids. Plasmids carry genetic material from one bacterium to another, which is where traits like antibiotic resistance are held.
Three ways bacteria obtain food
- Photosynthesis: Photosynthetic bacteria, such as green cyanobacteria, make their own food using light just like green plants do.
- Chemosynthesis: Chemosynthetic bacteria do not use sunlight, but instead produce their food using chemicals such as sulfate, ammonia, and hydrogen.
- Symbiotic feeding: Some bacteria get their food directly from other organisms, such as E. coli residing in the intestines and taking nutrients from the food humans eat.