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You may find it convenient to dissolve the ampicillin in 50% ethanol at 100 mg/ml, which allows it to be stored at -20C while still liquid. This makes it far easier to add to culture medium while keeping it cold. The ethanol also keeps it sterile. I would also be using carbenicillin rather than ampicillin, to avoid the breakdown at 37C on longer incubations.
#136401 Ampicillin kills my hands!
Posted
on 25 June 2012 - 12:55 PM
#134960 A faster way to pick single colony clones for PCR screening?
Posted
on 23 May 2012 - 05:11 PM
I do it by setting up a plate or strip with 50 ul pure water in each well. Then I use a 10 ul tip on a pipettor to touch a colony. The tip is suspended in the water and scraped against the sides of the well. The same tip is used to deposit 3 ul of the water onto a gridded master plate, then discarded. Afer picking colonies, a multi-channel pipet is used to transfer 0.5 ul of the water into a 10 ul pcr reaction with one primer on the insert and the other on the vector backbone. The master plate is incubated and the correct colonies prepared from the colonies with successful PCRs. If you feel confident, you can grow up some 10 ml cultures from a small number of the picked colonies on the chance that one of them is correct, potentially saving some time.
#133825 Calvin* is back with new season of Pseudopedia :)
Posted
on 01 May 2012 - 12:40 AM
Dear all some more new biology cartoons here...you can can also check them at:
http://biologyfun.blogspot.in/
http://biologyfun.blogspot.in/
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#133808 Uni question
Posted
on 30 April 2012 - 12:29 PM
IF you give us your attempts at answering these, then we can help further - these questions are for your benefit, not ours!
The first one is simple mathematics and some equations you should have learn't in high school science.
The second is also chemistry... for a cryptic answer think Homer: mmmmm B...
The first one is simple mathematics and some equations you should have learn't in high school science.
The second is also chemistry... for a cryptic answer think Homer: mmmmm B...
#132225 how to design primers for 16sr RNA
Posted
on 02 April 2012 - 12:42 PM
Conserved hypothetical means that the protein is found in many other species. You may want to look for hypothetical proteins that are not conserved.
#131540 "What People Think I Do / What I Really Do"
Posted
on 22 March 2012 - 01:24 PM
and many funny others...just google them...
#125285 Simple question of dNTP's for PCR
Posted
on 12 December 2011 - 03:37 AM
That won't work- because if you are adding equal amounts of four 100mM solutions together, you are increasing the total volume by a factor of 4 and therefore diluting each dNTP 1/4.
What I do is add 10ul of each dNTP then make up to 100ul with nuclease free water for a 1/10 dilution.
What I do is add 10ul of each dNTP then make up to 100ul with nuclease free water for a 1/10 dilution.
#125105 DNA ladder running faster than samples during agarose gel electrophoresis
Posted
on 08 December 2011 - 06:25 PM
Hmmm, I would trust the gel over supposed band sizes, especially if you are doing PCR! Waht percentage gel are you running for bands over 500bp, and under waht conditions - voltage, buffer etc?
#122954 Self-plagiarism?
Posted
on 03 November 2011 - 05:50 AM
you can reference your old dissertation but i'm also sure that your current writing ability is more polished than it was before so you'll be doing more paraphrasing than plagiarizing.
#122978 Self-plagiarism?
Posted
on 03 November 2011 - 08:47 AM
What do you mean with "the chapter" of your thesis? Anyway if it's one chapter of several it should be okay, because an undergrad study can be a good starting point of a phd thesis. But it shouldn't be too much (the extent of repetition is critical here) and it anyway makes not much sense to do the same work again??
#110128 question on molecular
Posted
on 17 May 2011 - 04:43 PM
How about doing your homeowrk yourself... we are usually happy to check answers you have come up with, but won't just give you the answers.
#91239 safety of CTAB?
Posted
on 02 November 2010 - 08:41 PM
CTAB is a detergent. It is as dangerous as SDS.
Thus the solution is safe so long as you don't drink it or wash your eyes in it. Same as any other detergent.
And similar to any powdered detergent, work with CTAB powder should be done in a fumehood. Breathing in detergent powder of any kind is harmful to your lungs.
As far as harmful chemicals go, I would call CTAB a bench top chemical, especially the solution. CTAB powder can be kept in a closed container on the bench, but I would only open the container in a fumehood.
Thus the solution is safe so long as you don't drink it or wash your eyes in it. Same as any other detergent.
And similar to any powdered detergent, work with CTAB powder should be done in a fumehood. Breathing in detergent powder of any kind is harmful to your lungs.
As far as harmful chemicals go, I would call CTAB a bench top chemical, especially the solution. CTAB powder can be kept in a closed container on the bench, but I would only open the container in a fumehood.
#91190 Why God Didn't Get Tenure
Posted
on 02 November 2010 - 11:55 AM
Why God Didn't Get Tenure
1. He had only one major publication.
2. It was in Hebrew.
3. It had no references.
4. It wasn't even published in a refereed journal.
5. Some even doubt he wrote it himself.
6. It may be true that he created the world, but what has he done since then?
7. His cooperative efforts have been quite limited.
8. The scientific community has had a hard time replicating his results.
9. He never applied to the Ethics Board for permission to use human subjects.
10. When one experiment went awry he tried to cover it up by drowning the subjects.
11. When subjects didn't behave as predicted, he deleted them from the sample.
12. He rarely came to class, just told students to read the Book.
13. Some say he had his son teach the class.
14. He expelled his first two students for learning.
15. Although there were only ten requirements, most students failed his tests.
16. His office hours were infrequent and usually held on a mountaintop.
1. He had only one major publication.
2. It was in Hebrew.
3. It had no references.
4. It wasn't even published in a refereed journal.
5. Some even doubt he wrote it himself.
6. It may be true that he created the world, but what has he done since then?
7. His cooperative efforts have been quite limited.
8. The scientific community has had a hard time replicating his results.
9. He never applied to the Ethics Board for permission to use human subjects.
10. When one experiment went awry he tried to cover it up by drowning the subjects.
11. When subjects didn't behave as predicted, he deleted them from the sample.
12. He rarely came to class, just told students to read the Book.
13. Some say he had his son teach the class.
14. He expelled his first two students for learning.
15. Although there were only ten requirements, most students failed his tests.
16. His office hours were infrequent and usually held on a mountaintop.
#87179 E.Coli growth at 4 degrees?
Posted
on 17 September 2010 - 05:31 AM
This doesn't have anything to do with your refrigerator -- you're seeing satellite colonies arising on the plate.
When you plate a transformation mixture, it contains many cells that haven't been transformed, and (hopefully) some that have. Initially, these cells without a plasmid don't grow because of the ampicillin in the media. However, as the transformed cells grow, they secrete beta-lactamase (the enzyme that destroys ampicillin and confers resistance on the transformants). As this enzyme accumulates in the media and diffuses outward, the concentration of ampicillin drops, because the enzyme is destroying the ampicillin. Now the untransformed cells can grow, as the concentration of ampicillin remaining is too low to stop their growth.
So, yes -- E. coli does grow at 4 degrees, and you shouldn't store your transformation plates directly, rather you should pick your transformants to a fresh plate and store that.
When you plate a transformation mixture, it contains many cells that haven't been transformed, and (hopefully) some that have. Initially, these cells without a plasmid don't grow because of the ampicillin in the media. However, as the transformed cells grow, they secrete beta-lactamase (the enzyme that destroys ampicillin and confers resistance on the transformants). As this enzyme accumulates in the media and diffuses outward, the concentration of ampicillin drops, because the enzyme is destroying the ampicillin. Now the untransformed cells can grow, as the concentration of ampicillin remaining is too low to stop their growth.
So, yes -- E. coli does grow at 4 degrees, and you shouldn't store your transformation plates directly, rather you should pick your transformants to a fresh plate and store that.
#85221 Dilution with %
Posted
on 30 August 2010 - 11:34 AM
sansub, on 30 August 2010 - 10:14 AM, said:
I want to make 100 mls of 5% glutaraldehyde from 50% glutaraldehyde. Is it ok to take 10 mls of 50% glutaraldehyde and bring it to a final volume of 100 mls?
I want to confirm if this is correct.
Thanks!
I want to confirm if this is correct.
Thanks!
Yes, that's correct.
