Types of Bacteria - EP1
2 Minutes
Types of bacteria for students: learn how bacteria are classified by their four shapes with examples. An English science lesson.
- How bacteria are classified by shape, flagella, and respiration
- Rod-shaped Bacillus anthracis and spherical cocci variations
- Spiral Helicobacter pylori and comma-shaped Vibrio cholerae
What this lesson teaches
Bacteria are categorized into different types based on their shape, the presence and arrangement of their flagella, and how they respire to breathe. When classified by their physical appearance, bacteria fall into four main shape categories: rod-shaped, spherical, spiral, and comma-shaped.
Three ways bacteria are classified
- Just as human beings can be grouped by observable traits such as being tall, short, dark, fair, or chubby, bacteria are categorized step by step.
- Scientists classify bacteria by their physical shape, dividing them into four primary forms.
- Bacteria are also classified by whether they possess flagella, including how many flagella are present and how they are arranged.
- Respiration, which is how these organisms breathe, provides a third method for grouping bacteria.
Rod-shaped and spherical bacteria
Rod-shaped bacteria have an elongated appearance that resembles rolled-up chapati rolls, with Bacillus anthracis serving as an example of this group. Spherical bacteria look like tiny little balls and are broadly known as cocci. When these spherical cells appear in pairs of two balls joined together, they are called diplococcus bacteria. Spherical bacteria can also link together in a line like a chain known as streptococcus, like Streptococcus pneumoniae, or cluster together in bunches in one place called staphylococcus.
Spiral-shaped bacteria
- Spiral bacteria represent the third shape category used to classify bacteria.
- Bacteria belonging to this group have a shape that looks like a spring.
- An example of a spiral-shaped bacterium is Helicobacter pylori.
- Helicobacter pylori clearly displays this spring or spiral shape.
Comma-shaped bacteria
Comma-shaped bacteria form the fourth major category, possessing a curved outline that looks just like the punctuation comma people write in exams. An example of a comma-shaped bacterium is Vibrio cholerae, which matches the curved shape of a comma precisely. This specific bacterium is responsible for causing the very dangerous disease known as cholera. Because cholera is such a severe illness, this comma-shaped organism is described as putting a full stop to many people's lives.