**Answer:**

**Viruses** do not have a regular cell structure.

**Explanation:**

**Viruses** are unique microorganisms that are distinct from other living organisms. They are considered as non-living particles or biological entities because they do not possess a regular cell structure. Here's an explanation of why viruses do not have a regular cell structure:

**1. Nature of Viruses:**
- Viruses are extremely small particles that are much smaller than cells.
- They are composed of genetic material, either DNA or RNA, surrounded by a protein coat called a capsid.
- Some viruses also have an outer envelope made up of lipids.

**2. Lack of Cellular Machinery:**
- Unlike other microorganisms such as bacteria, protozoa, and algae, viruses lack the cellular machinery required for independent metabolic activity.
- They do not possess the necessary organelles such as ribosomes, mitochondria, or the ability to carry out cellular respiration, protein synthesis, or other metabolic processes.
- Viruses are unable to generate energy, reproduce, or carry out any life processes on their own.

**3. Obligate Intracellular Parasites:**
- Viruses are obligate intracellular parasites, meaning they cannot replicate or carry out their life cycle without infecting a host cell.
- They invade the host cell and hijack its cellular machinery to replicate themselves.
- The virus uses the host's cellular machinery and resources to produce more virus particles, which eventually leads to the death or damage of the host cell.

**4. Classification as a Particle:**
- Due to their unique nature and lack of a regular cell structure, viruses are often referred to as particles rather than cells.
- They are considered to be on the boundary between living and non-living entities.
- Viruses exhibit some characteristics of living organisms, such as the ability to evolve and adapt, but they lack the ability to carry out independent life processes.

In conclusion, viruses are distinct from other microorganisms because they lack a regular cell structure and are dependent on host cells for their replication and survival.

A virus is an infectious agent which is very small and has a simple composition that can multiply only in living cells of animals, plants,etc.


Why it doesn't have a regular cell structure : Viruses do not have cells nor do they have a cell membrane. They have a protein coat that protects them .
Eg: Mitochondria