BIOL 100-Meyer

Start

The Biological Science Behind COVID-19

Image Credit: https://www.geeksforgeeks.org/characteristics-of-living-things/#

Defining life and its properties

What is life and how do we know if something is living? We can all understand that humans are living things, but what about something such as a tree? Although we can't see it moving or operating in the same ways that humans do, it is considered a living thing too. It eats, breathes, reproduces, etc. just as we do. In order for something to be considered living there is certain criteria it must meet and properties it must possess. However, information from Khan Academy states that a thing cannot only have some of these properties to be considered living, it must have them all. These properties are: 1: Organization-contain specialized parts that work together to create/maintain life (ex. our heart and lungs) 2: Metabolism-consuming of nutrients and use of energy to continue living 3: Homeostasis- must be able to regulate internal conditions needed for proper cell function 4: Growth- must be able to produce cell growth and/or division of cells 5: Reproduction-must be able to create new life (ex. pollenated seeds create new trees) 6: Response-must be able to respond to stimuli (ex. such as pain from a hot object) 7: Evolution-cells adapt to needed changes over time in order for a living thing to become more equipped for their environment

Image Credit: http://www.clipartpanda.com/clipart_images/classification-gif-26308044

Viruses-Living or non-living?

Viruses have long been categorized as non-living. As we covered in the information from Khan Academy on the previous slide, there are 7 points of criteria something must meet in order to be considered living. A virus, however, does not meet all of these points. First, a virus cannot reproduce on its own-it needs a host cell in order to replicate. Secondly, a virus cannot regulate its own temperature. Lastly I would like to mention that a virus does not need to consume nutrients or burn energy to survive.However, even though a virus is categorized as non-living, are they really dead? This is a question that many have asked and it seems to still be a topic of controversy and even somewhat of a blurry area. Even though a virus is not able to reproduce, it is able to replicate using host cells. Another reason there may still be controversy is because even though there are the properties of life, there seems to be no definite agreed upon definition of life.

Image Credit: GraphicsRF.com / Shutterstock.com

What are viruses?

Viruses are tiny, microscopic organism, that contains either RNA or DNA, which is surrounded by a protein coat called a capsid. A virus cannot thrive or reproduce without infecting a host cell to multiply. Once a virus multiplies, it bursts out of the host cell, resulting in the death of the host cell. The virus then looks for other host cells to infect in order to continue to multiply. (Microbiologysociety.org).

When looking at this information and trying to determine if a virus should be classified as living, I still believe they should not be thought of as living. In order to live virus cells are dependent on invading a host cell for all functions such as metabolizing and growth. A Prokaryotic cell, on the other hand is able to grow and reproduce on its own without a host cell.

Image Credit: NANOCLUSTERING / SCIENCE PHOTO LIBRARY

Image Credit: @ Getty Images

vs

Prokaryotic cells do contain cytoplasm, ribosomes, and also have cell structure.

Prokaryotes

A virus cell has no organelles, no cell structure and do not contain ribosomes or cytoplasm.

Virus Cell

Structural Differences

Image Credit: https://cdn-acgla.nitrocdn.com/bvIhcJyiWKFqlMsfAAXRLitDZjWdRlLX/assets/static/optimized/rev-5131b73/wp-content/uploads/2021/01/1-2.jpg

Cell Energy

A cell is able to produce energy by nutrients that have been imported into the cell and metabolized. Cells are modified as needed, such as carbohydrates are broken down into sugars or gluecose needed for energy. A virus on the other hand is unable to obtain or create its own energy source. Instead a virus has to take energy from the cell it invades and does not necessarily need energy outside its host cell (Davidson, 2015). While continuing to research if a virus should be considered living or not, I still do not feel as though it should. A virus continues to show that it is unable to survive without a host cell and that host cells functions.

Image Credit: https://quizlet.com/356995308/cell-cycle-reproduction-diagram/

Cell Division and Reproduction

There are two main ways that cells divide and reproduce. This happens through mitosis or meiosis. In our text, Concepts of Bilogy, it tells us that in mitosis there are seven phases a cell goes through-Interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. Also during these steps there are checkpoints cells go through to ensure they are "good" copies. The end result is two daughter cells being produced. Meiosis has two ways of cell division and reproduction. These are meiosis 1 and meiosis 2. In meiosis 1 the chromosomes are halved, whereas in meiosis 2 genetic information is halved in the chromosomes. The end result for this is four daughter cells. Viruses reproduce differently than other cells. They are unable to reproduce on their own. Instead, they must insert their genteic material into a host cell and then depend on the host to replicate and reproduce the virus protein.

Image Credit: https://www.howitworksdaily.com/wp-content/uploads/2013/11/cell-mutation.jpg

Cell Mutation

Cells mutation happens when there is a change in the replication sequence. These mutations result from errors in replication during cell division, viral infections, and/or exposure to mutagens (NIH, 2023). Virus mutations depend on a host or many host to house and replicate faster to extend its lifecycle. Without having a host to carry out mutation and the replication process, the virus essentially will die. A virus must have something to connect to or invade to carry out mutation of its contents.

Image Credit: https://i.redd.it/i-have-the-sleep-like-horse-only-3-hour-a-day-v0-ll16yldqaoda1.png?s=41a524bb6781d7b65f666910dcfd6ba6a8fe5716

Immunity to diseases/viruses

With so many viruses floating around, why does it seem that some people naturally never get sick? Well according to the publication, Do Some People Have Naturally Stronger Immune Systems, the answer is genetics. Some people may have resistance to infections due to their genetic make-up. For those who are not as lucky, this is where vaccines come in and help the body fight off infections. Vaccines introduce antigens of a virus or disease to the system which prompts the immune system to respond. This response helps the body fight off future bouts of the infections.

Image Credit: https://news.clemson.edu/wp-content/uploads/2021/09/dna-example02-1130x636.jpg

DNA/RNA in a cell

In a cell, DNA is what provides the coding for the cell activity whereas RNA turns the code into proteins that help carry out cell functions. In other words DNA maintains information and RNA uses the information provided by DNA to help a cel produce protiens to help us function (Bioinformatics.org). When it comes to viruses, RNA is able to provide its own "genetic" coding and replicate and carry out functions itself through a host.

Image Credit: https://www.bnl.gov/today/body_pics/2021/07/evolution-of-viruses-1000px.jpg

virus evolution

Just like cell life, viruses evolve too except a virus does so through a host cell. Viruses may even evolve through natural selection. A change in the viruses make up, such as swaping of DNA or RNA may cause mutation or viruses swaping bits of genetic material results in recombination (Khan Academy). Through the process of natural selection and mutations, the virus is able to better adapt to the current environment, thus the result of this process is evolution of the virus.

Image Credit: https://www.merriam-webster.com/assets/mw/images/source-original/2020-05-04_16-59-08---a34f7be7bdc15c0fd40bff87bf4329f3.png

Differences in Bacterial and viral diseases

There are a few key differences between bacterial diseases and viral diseases. One of the main differences I found throughout the research for this presentation is that bacteria cells can exist and survive on their own. On the other hand, viral infections are only able to exist once a virus has taken over a host cell. Another difference is bacterial diseases can be treated with antibiotics whereas viruses cannot.

Image Credit: http://www.quickmeme.com/img/5b/5b61cec948418dff462cc606a4b53bc05c4fd7f4a47f4d1aad44fe26591a69c5.jpg

Conclusion

In concluding this presentation, I still believe that viruses are non-living. They do not respond to stimuli nor are they able to grow or reproduce on their own, along with other functions. A virus must have a host cell in order to do any of these things or it can not survive.Along the lines of the controversy of whether a virus is living or non-living, I do think that if there is a solid set of guidelines enacted and followed of what characteristics must be present in order to be considered living, instead of it being somewhat fluid, this could possibly cut down on the amount of confusion and disagreement of what "living" is that seems to exist.

References

Are viruses dead or alive? (article). (n.d.). Retrieved from https://www.khanacademy.org/test-prep/mcat/cells/viruses/a/are-viruses-dead-or-alive Concepts of Biology Direct textbook. OpenStax. (2013, April 25). https://www.directtextbook.com/isbn/9781947172036 Davidson, M. W. (2015, November 13). Virus Structure. Molecular expressions cell biology: Virus structure. https://micro.magnet.fsu.edu/cells/virus.html Evolution of viruses (article). Khan Academy. (n.d.). https://www.khanacademy.org/science/ap-biology/natural-selection/common-ancestry-and-continuing-evolution/a/evolution-of-viruses Gilchrist, D. A. (2023, October 27). Mutation. Genome.gov. https://www.genome.gov/genetics-glossary/Mutation#:~:text=A%20mutation%20is%20a%20change,mutagens%20or%20a%20viral%20infection. The DNA, RNA and proteins. (n.d.). https://www.bioinformatics.org/tutorial/1-1.html#:~:text=Functionally%2C%20DNA%20maintains%20the%20protein,to%20synthesize%20the%20particular%20protein.&text=protein%2Dencoding%20information-,a.,the%20cell%20produces%20the%20protein. Villarreal, L. P. (2008). Retrieved from https://www.scientificamerican.com/article/are-viruses-alive-2004/

References

Viruses: What is microbiology?. What is microbiology? | Microbiology Society. (n.d.). https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/viruses.html What is life? (article). (n.d.). Retrieved from https://www.khanacademy.org/science/high-school-biology/hs-biology-foundations/hs-biology-and-the-scientific-method/a/what-is-life Wilson C. (2023). DO SOME PEOPLE HAVE NATURALLY STRONGER IMMUNE SYSTEMS?. New scientist (1971), 257(3424), 40–41. https://doi.org/10.1016/S0262-4079(23)00215-4