VIRUSES lesson 8: Viruses Inside Cells
This lesson brings together many things we’ve learned in past lessons. We are finally ready to go through the entire life cycle of a virus! We’ll look at two very different life cycles, one inside the nucleus and one outside. It makes sense to divide this lesson into two parts. Part (a) will be a DNA virus (herpes simplex) and part (b) will be an RNA virus (polio.)
Part (a): Herpes Simplex, a DNA virus
(Video runs about 60 minutes, but that includes coloring time.)
Here is the drawing template page you will need for 8(a):
Please note there are two info pages for 8(a). You will want to have the second page (list of events in the life cycle) handy while doing the drawing.
Info pages for Virus lesson 8a
If you need to see the final drawing, here is the one I did on camera:
Part (b): Polio, an RNA virus
(Video runs about 40 minutes.)
Here is the drawing template page you will need for 8(b):
Here is the info page for 8b:
Info page for Virus lesson 8(b)
If you need to see the final drawing, here is the one I did on camera:
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ACTIVITY IDEAS:
Activity 8.1: “VIRAL CRIMES and MISDEMEANORS”
Here is some bonus information that would not fit into the lessons. You’ll learn some of the ways that these evil geniuses interfere with cell processes, especially processes that are aimed at them! And to make it fun, we’ll draw each virus as a silly cartoon. (I use just a regular pencil, no colors needed.) Here is the link to the template page you will need: Template for Viral Crimes and Misdemeanors
Here is the link to the video, which runs 33 minutes: https://youtu.be/AtPgVvSUbzE
If you need a copy of the finished drawing, you can download it here: Finished sample of Viral Crimes and Misdemeanors drawing
Activity 8.2: Bonus information on Polio: How it is being used to treat disease
This is a very short video, only 6 minutes. I explain that bit of extra info at the bottom of the 8(b) info page. I very briefly explain the difference between the Salk and Sabin vaccines and how researches took the Sabin idea a step further and swapped out the polio IRES with a different one, rendering the polio virus a useful tool for attacking tumor cells that express the CD155 receptor on their surface.
Video link: https://youtu.be/fmr2N17-GiQ
Activity 8.3: A fun review quiz game
This is a “Jeopardy” type game, with multiple choice answers. You can play by yourself, or compete with one or more players. (The questions are very general and not super difficult. Meant to be easy review.) If you need a printed copy, there is a “print” option.
https://jeopardylabs.com/play/2020-05-08-497
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SUPPLEMENTAL VIDEOS:
You will recognize all the information in this video! However– this video gives you a different ending to the story. The virion will exit by going through the “secretory pathway” meaning through the ER and Golgi body. There might be different types of exits for different types of herpes viruses. Viruses from within one “family” can have distinct differences. So this might be the correct ending for one of the other types of herpes.
This video shows the processes of transcription and translation. (If you have already studied this you don’t have to watch.) To keep the words straight, think of “transcription” being a scribe making a copy of a manuscript (script/scribe) like they did in the Middle Ages. Think of translation as going from one language to another language. The first language is the language of nucleic acids and has the letters A,T, U, C, G, and the second language is the language of proteins where the words are the names of amino acids. The bilingual translator’s name is “tRNA.” The rRNA molecule understands DNA/RNA code and can apply the correct amino acid.
https://www.youtube.com/watch?v=8_f-8ISZ164
Here is another short (3 min) video on translation, with a really nice animation showing how fast a ribosome works (“in real time”).
REVIEW OF PLAQUE ASSAY TEST:
Do you remember plaque assays from way back in lesson 4? D’Herelle used this technique a century ago, and today it is still the best test to do if you want to find out how many virions it takes to cause an infection. Not all virions will be able to infect a cell. There are hundreds of things that can go wrong in the copying and manufacturing process, and most virions produced are defective in some way (good news for us!). Also, the body is pretty good at fighting back and it often takes quite a few virions to make us sick. One lonely influenza virion entering out body probably won’t make us sick.
So how do virologists determine how many truly infectious virions are produced by certain viral species? Let’s listen to an expert virologist explain how they count viruses with a plaque assay.
Ready to take the quiz?
If you can’t access the online quiz or need a printed copy for any reason, here is a pdf version you can use (includes the answer key).
(NOTE: There aren’t any questions on the quiz about the info from the activities.)
