Viruses

Viruses are tiny infectious agents that can only replicate inside the cells of living organisms. They are not considered to be living organisms because they do not meet all the criteria for life, such as the ability to carry out metabolic processes or reproduce on their own. Instead, viruses hijack the cellular machinery of their host organisms to replicate and spread.

Structure of Viruses

Viruses consist of genetic material, either DNA or RNA, surrounded by a protein coat called a capsid. Some viruses also have an outer lipid envelope. The genetic material contains the instructions for making new virus particles, while the capsid protects the genetic material and helps the virus attach to host cells.

Replication of Viruses

When a virus infects a host cell, it injects its genetic material into the cell. The viral genetic material then takes over the host cell's machinery, forcing it to produce new virus particles. These new viruses can then infect other cells and continue the cycle of infection.

Types of Viruses

Viruses can infect all types of organisms, including animals, plants, and bacteria. They come in various shapes and sizes, and can cause a wide range of diseases, from the common cold to more severe illnesses such as Ebola and COVID-19.

Study Guide

1. What are the main components of a virus?
2. How do viruses replicate inside host cells?
3. What is the difference between RNA and DNA viruses?
4. Give examples of diseases caused by viruses.
5. What are the characteristics of viruses that distinguish them from living organisms?

Hope this study guide and explanation helps you understand the topic of viruses better!