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Artistic enhancement of a transmission electron microscope image of the COVID-19 virus. |
- In June of 1973, I began teaching biology at Monte Vista High.
- If this “story” wasn’t part of my first year’s teaching, it arrived soon thereafter.
- Originally presented on a chalkboard, then a whiteboard, then via an overhead projector, and in the 1990s and beyond as Apple's early presentation software then PowerPoint, the original diagrams were hand-drawn.
- Mercifully for you, the diagrams in this PPT are not.
- Of course, although you do get better visuals, you don't get the "show" that my lecture was. <snicker>
This post is long in scrolling, but not in verbiage. Hang in there.
An important aside
This is important information because
Viruses
- are not made up of cells.
- reproduce only in a host using their cellular equipment.
- DO have DNA or RNA.
- don't grow or develop.
- use a cell's energy, not their own.
- don't respond to their environment, except to go dormant.
- don't control anything about their internal or external environment.
- DO mutate DNA or RNA. HIV and other viruses mutate so frequently that the chance of developing a vaccine for them is LITTE TO NO CHANCE.
Conclusion of the Aside:
- A LIVING ORGANISM MUST "DO" ALL 8 LISTED ITEMS.
- VIRUSES "DO" ONLY TWO OF THEM.
- VIRUSES ARE NOT ALIVE. YOU CANNOT KILL THEM.
The Saga of Victor the Virus
Hosts of viruses tend to be species or scientific classification group-specific. They don't infect every organism they make contact with.
This comic strip illustrates how a bacteriophage (a virus that attacks bacteria) works.
Viruses that attack your cells function in the same way. In fact, it's easier for a virus to enter your cells because your cells don't have cell walls.
If you think about what kinds of molecules cells need to function (Hint: Include protein in your list!) and what the outside of a virus is made of, you might be able to figure out why viruses can enter your cells easily.
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| Victor is a Bacteriophage-a type of virus that attacks only bacteria. Cold viruses are Adenoviruses. A retrovirus contains RNA, not DNA. It mutates after every few replication cycles of each version of the virus. |
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| Additional types of viruses. |
A viral particle approaches a bacterial cell wall.
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| Yellowish shapes are bacteriophages. |
All viruses, as you should recall, do only one thing VERY WELL: reproduce. However,
Aside #2.
End of Aside #2
the virus must be inside a host cell or it cannot reproduce.
To get inside the host bacterium, the contractile sheath contracts, and the viral DNA is injected into the bacterium. Aside #2.
- Your cells have membranes as their outer border, not cell walls.
- Viruses that infect your body don't need to inject anything into your cells because the outer covering of viruses contains proteins.
- When viruses "land" on your cells, your cell membranes recognize the virus as a source of protein.
- Sensing the protein as food, the cell membrane engulfs the virus and brings it inside the cell.
- The virus does nothing to gain entrance exept land on the cell membrane.
End of Aside #2
Sometimes the viral DNA attaches to the bacterial DNA. This temperate phage is replicated every time the bacterium divides. The herpes viruses that cause cold sores in you are like this. The virus can remain inside the bacterial hosts, or your lip cells, for years.
But isn't an intact virus more than DNA?
Correctamundo!
Now that we find out that "Victor" is a lot like Clark Kent. Just like inside Clark is Superman, inside the protein coat of the virus is the functioning part: DNA.
DNA must enter the host or nothing will happen. Once inside the bacterium, two possible endings to the story exist. Bacteria (or your lip cells) are not aware that they are infected. Pretty boring.
Now that we find out that "Victor" is a lot like Clark Kent. Just like inside Clark is Superman, inside the protein coat of the virus is the functioning part: DNA.
DNA must enter the host or nothing will happen. Once inside the bacterium, two possible endings to the story exist. Bacteria (or your lip cells) are not aware that they are infected. Pretty boring.
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Under certain conditions, like radiation from the sun at the beach, can cause the virus to "escape" from its place in the bacterial DNA. When the virus escapes, it leads to …
An environmental signal can trigger the virus DNA to exit the bacterial chromosome and switch to the lytic mode.
For example, when triggered
An environmental signal can trigger the virus DNA to exit the bacterial chromosome and switch to the lytic mode.
For example, when triggered
Herpes simplex-1 --> Cold sores
Exposure to ultra-violet radiation in sunlight is one trigger of Herpes simplex-1 to begin the lytic cycle that ends in cold sores.
Using the host bacterium's (or your lip cell's) enzymes and energy sources, the viral DNA replicates itself. The multiple copies of the viral DNA direct the ribosomes of the cell to begin making viral coat protein.
Something, scientists do not know what triggers the virus sub-parts to combine, or how virus sub-parts assemble into virus particles. One of my professors said that step convinces many researchers of the existence of God.
During the lytic cycle, the host cell is destroyed (lysed). An enzyme is produced which weakens the cell membrane (and wall if the cell is a plant, fungus, or bacterium) of the host. The cell boundary ruptures.
Thousands of newly assembled virus particles are released into the environment to infect other cells.
Vaccines usually damage viral DNA. Since damaged DNA cannot function properly, these attenuated viruses cannot infect and lyse hosts.
Radiation is used to damage viruses. Just like radiation is harmful to the DNA in your cells, it is harmful to viral DNA as well. That is why many hospitals use ultra-violet lights in operating rooms between surgeries.
One use of the word "kill" I don't like at all is when it's used in reference to viruses. There are ways to damage viruses and reduce or eliminate their ability to infect cells and use those cells' internal structures to replicate.
Closing Aside
Since viruses are not alive, antibiotics do not have any effect on most viruses. There are anti-viral drugs, of course, but medicine used for first aid or bacterial infections are useless against viruses.
Remember that the outer coating of a virus is protein, sometimes phospholipids, also found in your cell membranes, are present, too. If conditions exceed the range where a virus can function, the proteins begin to denature. They unfold from their functional form to a non-function form. Non-functional protein is recognized by your cells and is not ingested like functional proteins are.
An egg white is made of proteins When a raw egg is cracked, the white isn't white, it's opaque. When you cook the egg white, nothing happens until the temperature reaches the critical temperature.
Denaturation is the physical changes in protein when it is exposed to abnormal conditions in the environment.
Mechanical agitation, heat, acid, high salt concentration and alcohol can cause proteins to denature.
(Denaturation can only occur in protein foods)
When proteins are denatured, what happens is that the protein bonds are broken down and the natural state of the protein structures is unraveled and becomes a single strand of amino acids. http://aifujita-moleculargastronomy.weebly.com/denaturation-and-coagulation.html
Egg white protein coagulates, this occurs after denaturing, between 144° F and 149° F (62.2° C and 65° C). I couldn't find agreement among various websites for the temperature extremes that are functional limits for the COVID-19 virus.
Bottom Line
- Avoiding or limiting time in areas where COVID-19 might be found and washing your hands are your best protective actions against this disease.
- Dawn is an excellent choice to combine with water because Dawn helps dissolve the outer layer of the virus making it less appealing to your cell membranes.
- In addition, it washes easily off your skin, taking whatever it traps with it. That's why they use it on oil-covered animals after oil spills.
Many illustrations in this post are from a PowerPoint Copyright 2008, Pearson Education, Inc., publishing as Pearson Benjamin Cummings. If you'd like to see the entire PPT or a version that goes into more depth, email me for either or both URLs.
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