Structure and Reproduction of Bacteria, Viruses, Fungi and Parasites

Bacteria are single-celled organisms.
Their basic structure includes a cell membrane, a cytoplasm, ribosomes, a nucleoid (DNA material), and some have a capsule for protection.
They replicate or multiply through a process called binary fission, an asexual process where one cell divides into two identical cells.
The shapes of bacteria include Cocci (round), Bacilli (rod-like), and Spiral.
Some bacteria are beneficial, such as those in the gut flora, while others can cause diseases.

Viruses are tiny infectious agents that need a host cell to replicate.
They contain genetic material (either DNA or RNA) surrounded by a protein coat, known as a capsid. Some have an additional layer, the envelope.
Viruses infect a host cell and take over its machinery to replicate, producing numerous virus particles.
These new virus particles release from the host cell to infect more cells.
Viruses cause a range of diseases across various species, from influenza to rabies.

Fungi are eukaryotic organisms and can be single-celled or multicellular.
They have a complex structure which includes a cell wall, a nucleus, cytoplasm, and organelles.
Fungi reproduce both asexually (through budding or spore formation) and sexually (through fusion of haploid cells, followed by meiosis).
Fungi include yeasts, moulds, and mushrooms. Some are helpful, like yeasts involved in bread production, others cause diseases (ringworm, athlete’s foot).

Parasites are organisms that live on or in another organism (the host) and benefit at the host’s expense.
They can be unicellular like protozoa, or multicellular like worms and arthropods.
Parasites exhibit a wide range of reproductive strategies, depending on their species. This includes asexual reproduction (binary fission, budding, or schizogony) or sexual reproduction.
Parasites cause different diseases in animals. For example, ticks can transmit Lyme disease, while fleas can transmit parasitic worms.
Control and prevention of parasites are of utmost importance in animal management.