Gene Upregulation/Overexpression

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scienceluvr
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Gene Upregulation/Overexpression

Post by scienceluvr » Fri May 08, 2009 12:16 am

Hi,

Can someone please explain to me what gene overexpression or upregulation is in laymen's terms? I am doing a science fair project on a similar topic and am having difficulty explaining it in a simple way.

Thank you so much!

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Post by MrMistery » Fri May 08, 2009 1:46 pm

you make more mRNA for that gene. In upregulation, you transcribe the gene more in response to some signal. this is a natural operation performed by a cell. Overexpression is usually used to refer to an experimental approach: by using simple biotech approaches, a researcher can artificially modify the gene so that the cell makes more mRNA from it.
More mRNA usually leads to more protein from that gene.

Laymen's terms enough?
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Re: Gene Upregulation/Overexpression

Post by scienceluvr » Fri May 08, 2009 7:29 pm

Thanks.

One more question: So for overexpression: if you add a plasmid to a cell that already has organism's genomic DNA, you would be overexpressing the particular gene on the plasmid because more of the gene implies it will make more of the mRNA?
The gene on the plasmid also exists within the genome of the organism (a yeast).
Thanks,
Scienceluvr
Last edited by scienceluvr on Sat May 09, 2009 1:41 am, edited 1 time in total.

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Post by MrMistery » Fri May 08, 2009 11:21 pm

i think yeah, technically a plasmid is still in the genome.
And regarding your first question: depends on what kind of promoter the gene on your plasmid has. It will only be overexpressed if the promoter actually makes it get transcribed.
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Re: Gene Upregulation/Overexpression

Post by scienceluvr » Sat May 09, 2009 1:29 am

Thank you for your help :)
A few more things...

How can I check if the promoter will make the gene be transcribed? Or can I check at all?

Also, one more question: If I am simply explaining gene expression, not overexpression, how should I go about that?

I'm trying to explain it without using the word express in it; it seems like a basic concept to me, but that is the reason I'm having difficulty explaining it without using the words "gene expression".

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Post by MrMistery » Sat May 09, 2009 9:32 pm

gene expression=making a protein from your gene.

Regarding your promoter question: yes, but it's hard. if you put it there specially to have it expressed, then obviously you have an active promoter (unless you're utterly stupid). But there are plasmids that do not have promoters at all: they are only meant to make the bacteria copy the gene, not to express it. if you have the name of your plasmid, you can usually check with the manufacturer, they will have a map that will tell you what your promoter is. if it's a viral promoter then you're all set. If it's not, you don't really know unless you search the literature for it. Generally speaking though, a promoter WILL express your gene - that's what a promoter does. It's just that a lot of promoters aren't active all the time. For example, the lac promoter is not active if the bacterium doesn't have a CAP protein.

I'm sorry, did i totally confuse you just there? This is kinda the nitty-gritty work of molecular cloning, there's no simple right or wrong answer.
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