10 Answered Questions for the topic lab techniques

07/27/19

How does formaldehyde/PBS or methanol fixation of cells affect lysosomal pH?
**The question** is fairly simple - does formaldehyde or methanol fixation in preparation for immunocytochemistry/immunofluorescent staining affect the pH of the lysosomes?**Some background:** I'm... more
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Lab Techniques Microbiology Materials

07/22/19

Help with preparing Congo Red TSA?
So I want to make Congo Red TSA. My instructor gave some hints but I still have some questions: 1. I start by making two stock solutions: 20 mg/ml of congo red and coomassie in two different... more
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Lab Techniques Biochemistry Dna Dna Isolation

06/26/19

What are the roles of guanidine-HCl and ethanol in binding of DNA to silica?
I'm trying to understand how exactly the binding to silica gel (in kits) step works and I cannot find any papers which provide an explanation of the physics or chemistry; especially on the way that... more
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06/21/19

Using ion-exchange chromatography to purify DNA from a cell extract - Is DNA more negatively charged then RNA?
When applying this method we have a glass or plastic column of resin which is positively charged. Then we pour cell extract into the column in order to capture the negatively charged particles... more
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06/17/19

Role of calcium chloride during competent cell preparation?
I am aware of the fact that $CaCl_2$ settles down on the cell wall making it less negative may be by forming bond with Teichoic acid. Also due to the positive charge it attracts DNA (DNA is... more
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Lab Techniques Biochemistry Sds Page

06/13/19

What kind of "size" does SDS-PAGE separate by?
What is the exact property of the protein that affects migration of bands in SDS-PAGE; is it length, volume, or mass?For example, will `GGGGGGGGGG` (glycine 10-mer; mw <600) migrate more or less... more
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Lab Techniques Genetics Snp Molecular Biology

05/30/19

What method would you use to genotype SNPs in low quality samples?
What method would you use to genotype SNPs in low quality samples? I ideally want to genotype hundreds of SNPs in hundreds of scat samples (very low amount of target DNA, potentially degraded and... more
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05/28/19

What are the advantages and disadvantages of using beta-galactosidase compared to luciferase as a reporter gene?
In the University labs, we have used Beta-galactosidase as a reporter gene to quantify the expression initiated by the stress-response promoter in yeast. This was done by exposing one of the two... more
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Lab Techniques Biology Cell Western Blot

03/19/19

Procedure for doing western blot?
I am writing a step by step guide for doing a western blot for a class. It is intended for any one with basic Biology lab skills. I am hoping people will review my draft and give feedback on how... more
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03/14/19

Why should I degas my gel solution for polyacrylamide gels?
In protocols for polyacrylamide gel electrophoresis (PAGE) I often see instructions to degas the gel solution by putting it under vacuum for 10-15 minutes before polymerizing the gel. I usually... more
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