What is Bacteria?

Study Notes

Bacteria are small, single-celled organisms found almost everywhere on Earth.
They are vital to the planet's ecosystems and can live under extreme conditions of temperature and pressure.
The human body contains more bacterial cells than human cells, with most being harmless and some even helpful.

Bacteria are classified into four major groups based on their cell shape and physical structure:
- Spherical (cocci)
- Rod (bacilli)
- Spiral (spirilla)
- Comma (vibrios)

Bacteria reproduce through binary fission, an asexual mode of reproduction.
A single bacterium divides into two identical daughter cells.
Replication of DNA within the parent bacterium marks the beginning of the fission.
The rate and timing of reproduction depend on conditions like temperature and availability of nutrients.

Not all bacteria are harmful to humans; some are beneficial in different ways:
- Convert milk into curd (Lactobacillus)
- Ferment food products (Streptococcus and Bacillus)
- Help in digestion and improving the body's immunity system (Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria)
- Produce antibiotics (Soil bacteria)

Bacteria cause diseases in plants and animals, leading to indirect human impacts.
Bacteria cause many human diseases, entering the body through openings, air, food, and water, or through skin wounds.
Bacterial diseases harm people in two ways:
- Interfering with normal body tissue function
- Releasing toxins that directly attack the host
Additionally, bacteria are linked to:
- Cancer
- Food spoilage
- Allergies and chronic inflammation
- Flesh-eating diseases
- Infectious diseases like pneumonia, tuberculosis, and tooth decay
- Cellulose degradation, destroying textiles and wooden articles