• Question: what is the structure of a virus, and are they living things?

    Asked by anon-244767 on 29 Apr 2020.
    • Photo: Alena Pance

      Alena Pance answered on 29 Apr 2020:

      A virus is a tiny capsule, like a a polyhedral cup made of lipids (fatty molecules) that contain the genetic material. This can be DNA or RNA and it codes for all the information the virus needs to penetrate a cell and replicate within it. The amount of DNA or RNA it has is very small, as an example the COVID19 virus has a genome of 30000 bases of RNA, which is tiny compared to the 3 billion base pairs of DNA every one of our cells has! So viruses generally hijack the machinery of the cell it invades to make more copies of itself.
      As to whether they are living things, that is a very good question indeed. On one hand they have genetic material and invade cells, replicate themselves and invade new cells, which is a feature of living parasite really. At the same time, they don’t have enough genetic material to be able to perpetuate themselves without the host cell and can crystallise and remain in suspended animation as it were for long periods of time, which are not features of living things. So viruses don’t really fit into the existing biological classification.

    • Photo: Emilio Garcia

      Emilio Garcia answered on 30 Apr 2020:

      Viruses are generally made up of three parts: genomic information in the form of DNA or RNA, a protective protein shell called the capsid, and an outer layer called the envelope. Some viruses, however, can be non-enveloped. Viruses are generally not considered living things because they don’t adhere to the characteristics used to define life: “the properties of life”.

    • Photo: Sophie Pritchard

      Sophie Pritchard answered on 30 Apr 2020:

      You can find some great information and diagrams about virus’ and their structure here: https://www.khanacademy.org/science/high-school-biology/hs-human-body-systems/hs-the-immune-system/a/intro-to-viruses

    • Photo: Olivia Edwards

      Olivia Edwards answered on 30 Apr 2020:

      Viruses are very small structures consisting of a protein ‘shell’ with some genetic code inside. This code can be made of either DNA or RNA, and will include instructions for the virus to be able to divide and infect its host.
      Viruses sometimes contains another outer coating called an envelope, and this is made from ‘fats’ (phospholipids) and proteins.

      A virus is not considered to be living, this is because on it’s own it is unable to copy itself. Living cells will contain proteins and other molecules inside them which are needed for it to divide, and viruses need to get inside these cells and ‘borrow’ these to copy itself. Once it has made many more copies of itself they will then escape from the cell and go and infect others. Often this will cause the cell it is in to be destroyed.

    • Photo: Sandra Greive

      Sandra Greive answered on 30 Apr 2020:

      I love this question! And all the great answers.

    • Photo: Marta Dazzi

      Marta Dazzi answered on 30 Apr 2020:

      A virus is a tiny particle that is a lot smaller than a living cell. It consists of packets of nucleic acid and protein and can only “live” inside a host cell. It makes use of the cell’s resources to reproduce, essentially making the host cell into a virus factory! Since it can only live when inside a cell, it is not considered to be living.

      There are large varieties of viruses and their structures differ but in general they have genetic material (DNA or RNA) encapsulated by a protein shell (capsid). The capsid is made up of many proteins joined together called capsomers. It’s the virus’ genetic material that provides instructions on how to make capsids. Capsids can come in different shapes and sizes. For example, it can be in the shape of a soccer ball, a long cylinder or made up of a combination of a cylinder and soccer-shaped body. Some viruses also have a membrane called the envelope. Envelopes contains proteins produced by the virus that can help them bind to host cells and cause infection.

    • Photo: Angela Downie

      Angela Downie answered on 30 Apr 2020:

      This is a very good question indeed! And as you have probably gathered from the previous responses one that is quite hard to answer! I would agree with previous answers saying that viruses are not living things because they need other cells to carry out their basic functions, however I will say that viruses make us think really hard about what we consider a living thing.They are annoyingly hard to classify because they are right on the edge of what we consider living or not living and don’t really fit 100% into either side.