Microbe Mission B/C

Test your knowledge of various Science Olympiad events.
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Re: Microbe Mission B/C

Postby sciduck » October 19th, 2017, 8:02 pm

Got it, thanks.
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Re: Microbe Mission B/C

Postby whythelongface » October 19th, 2017, 8:45 pm

Name one example of a granulocyte and its function in the human body.
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Re: Microbe Mission B/C

Postby Alex-RCHS » November 2nd, 2017, 9:23 pm

No idea, and it's been a while so here are some unnecessarily difficult* microscopy questions:

1. Explain what a dichroic mirror is and what types of microscopes use one. Also, explain what two light beams pass through the dichroic mirror and what those two beams will eventually hit.

2. Briefly describe Rheinberg Illumination. (How does it work, how does the image appear, etc.)

3. Explain the difference between an achromat and plan objective lens. How is each one corrected? Note: There is such a thing as a plan-achromat lens, but I'm asking you to ignore that for now.

4. I have a compound light microscope that I can only use to view in brightfield. What part do I need to be able to view in darkfield?

*In my defense, I believe that 4 is a reasonable question to ask on a test. The other three are hard, perhaps unreasonably so. I'm curious as to what you all think.
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Re: Microbe Mission B/C

Postby whythelongface » November 3rd, 2017, 3:56 pm

No idea, and it's been a while so here are some unnecessarily difficult* microscopy questions:

1. Explain what a dichroic mirror is and what types of microscopes use one. Also, explain what two light beams pass through the dichroic mirror and what those two beams will eventually hit.

2. Briefly describe Rheinberg Illumination. (How does it work, how does the image appear, etc.)

3. Explain the difference between an achromat and plan objective lens. How is each one corrected? Note: There is such a thing as a plan-achromat lens, but I'm asking you to ignore that for now.

4. I have a compound light microscope that I can only use to view in brightfield. What part do I need to be able to view in darkfield?

*In my defense, I believe that 4 is a reasonable question to ask on a test. The other three are hard, perhaps unreasonably so. I'm curious as to what you all think.
What

I remember reading about dichroic mirrors, but I don't remember them now. I think that it's permissible to search this up.
Dichroic mirrors have different reflective properties at different wavelengths. For that reason, there are used in fluorescence microscopy (including confocal). Light at wavelength A is reflected onto the sample. Fluorescent dyes absorb and re-emit light at wavelength B, which travels through the mirror (which is less reflective at wavelength B than A) and then observed through either a traditional lens setup OR a pinhole, in the case of a confocal microscope.

IDK about any of the others, although I think I SHOULD know #4.
WEST WINDSOR-PLAINSBORO HIGH SCHOOL SOUTH '18
EMORY UNIVERSITY '22
SONT 2017 5th Place Medalist [Microbe Mission]

"One little Sciolyer left all alone,
He went out and hanged himself and then there were none."

Congratulations to WW-P South for winning 14th place at Nationals!

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Re: Microbe Mission B/C

Postby Alex-RCHS » November 3rd, 2017, 6:37 pm

No idea, and it's been a while so here are some unnecessarily difficult* microscopy questions:

1. Explain what a dichroic mirror is and what types of microscopes use one. Also, explain what two light beams pass through the dichroic mirror and what those two beams will eventually hit.

2. Briefly describe Rheinberg Illumination. (How does it work, how does the image appear, etc.)

3. Explain the difference between an achromat and plan objective lens. How is each one corrected? Note: There is such a thing as a plan-achromat lens, but I'm asking you to ignore that for now.

4. I have a compound light microscope that I can only use to view in brightfield. What part do I need to be able to view in darkfield?

*In my defense, I believe that 4 is a reasonable question to ask on a test. The other three are hard, perhaps unreasonably so. I'm curious as to what you all think.
What

I remember reading about dichroic mirrors, but I don't remember them now. I think that it's permissible to search this up.
Dichroic mirrors have different reflective properties at different wavelengths. For that reason, there are used in fluorescence microscopy (including confocal). Light at wavelength A is reflected onto the sample. Fluorescent dyes absorb and re-emit light at wavelength B, which travels through the mirror (which is less reflective at wavelength B than A) and then observed through either a traditional lens setup OR a pinhole, in the case of a confocal microscope.

IDK about any of the others, although I think I SHOULD know #4.
Ah yes, in my midnight ramblings I thought those might be reasonable questions, but now I see that they are probably too hard. Well, I don’t know... rule 3d1 somewhat covers questions 2 and 4 and maaaaybe 1 or 3. They’re definitely pretty difficult.

If anyone else wants to answer, please go ahead. Otherwise I’ll post the answers soon.
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Re: Microbe Mission B/C

Postby sciduck » November 4th, 2017, 7:40 am

4. I have a compound light microscope that I can only use to view in brightfield. What part do I need to be able to view in darkfield?
To make a bright field microscope into a dark field one, you add something to block out the middle of the light source. I think it's called a patch stop, but I can't remember (maybe filter or mask?)
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Re: Microbe Mission B/C

Postby Alex-RCHS » November 4th, 2017, 9:49 am

1. Whythelongface is correct. Dichroic mirrors are used in CLSM because they reflect some wavelengths and allow others to pass through them. The excitation wavelength reflects off the mirror but the emission wavelength passes through it and is detected by the microscope. 
2. Rheinberg Illumination works by placing a filter in front of the light source. The outer ring of the filter (annulus) is one color, and the inner part (the stop) is another. Therefore, the specimen is stained the color of the inner ring and the background is the color of the outer ring. Scroll down this page for some really cool examples: http://www.quekett.org/resources/rheinberg
3. A plan objective lens has complete flat-field correction. That means the entire field appears in focus, as opposed to other objectives in which the outer ~40% of the field appears out of focus. Side note: semi-plan objectives have partial correction, so that only the outer ~20% appears out of focus. An achromat lens is corrected for spherical and chromatic aberration. I don’t remember what spherical aberration is, but chromatic aberration is when different wavelengths are refracted differently and therefore one color appears shifted or out of focus. TBH, I don’t understand this too well. 
4. Sciduck is correct, you need a patch stop for this. It blocks out the middle light so the only light hitting the sample does so at such an oblique angle that the light passing through does not hit the objective. The background appears dark because of the shadow of the patch stop.
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Re: Microbe Mission B/C

Postby The48thYoshi » November 8th, 2017, 7:13 am

I guess I’ll post a question if no one else wants to.
Explain the relationship between HDV and HBV.
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Re: Microbe Mission B/C

Postby Unome » November 8th, 2017, 8:38 am

HDV coinfects with HBV. I think it exacerbates symptoms, but wouldn't know for sure without my notesheet.
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Re: Microbe Mission B/C

Postby The48thYoshi » November 8th, 2017, 9:45 am

HDV coinfects with HBV. I think it exacerbates symptoms, but wouldn't know for sure without my notesheet.
HDV can not infect a cell without HBV. It can infect cells already infected by HBV in a superinfection, or a coinfection with both viruses simultaneously. Either way,  it does exacerbate symptoms as you said.
Your turn.
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