2.4. Summarise the characteristics of: • bacteria • viruses • fungi • protozoa

This guide will help you answer 2.4. Summarise the characteristics of: • bacteria • viruses • fungi • protozoa.

Understanding the characteristics of microorganisms helps maintain health and safety in health and social care settings. These tiny organisms can affect human health, causing diseases or infections. Let’s explore the defining features of bacteria, viruses, fungi, and protozoa.

Bacteria

Structure and Characteristics

• Single-celled organisms: Bacteria are unicellular, meaning they consist of just one cell.
• Cell wall: Most bacteria have a rigid cell wall that provides shape and protection.
• Shapes: They appear in various shapes such as rods (bacilli), spheres (cocci), and spirals (spirilla).
• No nucleus: Unlike eukaryotic cells, bacteria do not have a true nucleus. Their DNA floats freely within the cell.
• Reproduction: Bacteria reproduce asexually through a process called binary fission, where one cell divides into two identical cells.

Growth and Survival

• Conditions for growth: They thrive in various environments, some preferring heat, others cold. Many need moisture and nutrients.
• Survival mechanisms: Some bacteria form spores under harsh conditions, allowing them to survive until conditions improve.
• Benefits and Harm: While many bacteria are beneficial for human health, such as those in the gut, others can cause infections like strep throat or tuberculosis.

Viruses

Structure and Characteristics

• Non-cellular: Viruses are not considered true living organisms because they cannot reproduce independently.
• Simple structure: They consist of genetic material (DNA or RNA) surrounded by a protective protein coat, known as a capsid.
• Size: Viruses are much smaller than bacteria and require powerful microscopes to be seen.

Replication and Infection

• Host requirement: Viruses need a host cell to reproduce. They invade cells, take over their machinery, and produce new virus particles.
• Disease-causing: Many viruses cause diseases, such as the flu, HIV, and COVID-19.
• Transmission: Viruses spread through various means, including air, bodily fluids, and contaminated surfaces.

Fungi

Structure and Characteristics

• Eukaryotic organisms: Fungi have complex cells with a nucleus and organelles.
• Cell wall: Fungal cells have a rigid cell wall made of chitin, unlike the cellulose found in plant cell walls.
• Forms: They exist as yeasts (single-celled) or moulds (multicellular, thread-like structures).

Growth and Reproduction

• Nutrient absorption: Fungi obtain nutrients through absorption, often breaking down organic matter.
• Reproduction: They can reproduce sexually or asexually, often via spores that disperse through the air.
• Roles: Fungi play essential roles in nutrient cycling in ecosystems. However, some may cause infections, like athlete’s foot or thrush.

Protozoa

Structure and Characteristics

• Single-celled eukaryotes: Unlike bacteria, protozoa have a nucleus and organelles.
• Diverse forms: They come in various shapes and sizes, often larger than bacteria and viruses.

Movement and Feeding

• Locomotion: Many protozoa move using structures like cilia (tiny hair-like structures) or flagella (tail-like structures).
• Feeding: They often feed on bacteria, algae, or other protozoa, playing critical roles in aquatic environments.
• Reproduction: Protozoa reproduce mainly through binary fission but can also engage in sexual reproduction.

Health Impact

• Pathogenic protozoa: Some protozoa cause diseases such as malaria and giardiasis. They can be transmitted through contaminated water or insect bites.

Final thoughts

Understanding these microorganisms helps manage health risks and improve outcomes in care settings. Each has a unique structure and impact on human health, and addressing them appropriately is essential for maintaining a safe and healthy environment.