Jul 5, 2009
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operons in prokaryotic genes (not sure for eukaryotic) have 1.promoter,2,operator 3, gene clusters and I'm wondering where is the place for a repressor protein attach to prevent transcription to control gene expression?

is it operator or promoter?

Thanks in advance!1
 
May 22, 2009
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promoter is where DNA polymerase would attach. Operator is where repressors would attach. Where are the gene clusters???
 

Sugafoot79

10+ Year Member
Feb 3, 2009
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promoter is where DNA polymerase would attach. Operator is where repressors would attach. Where are the gene clusters???
I'm confused...

During transcription, in initiation, the RNA polymerase (not DNA polymerase. DNA polymerase is used in DNA replication) attaches to the promoter region of the DNA and begins to unzip the DNA into two strands.

From Wikipedia:
An operon is a functioning unit of key nucleotide sequences of DNA including an operator, a common promoter, and one or more structural genes, which is controlled as a unit to produce messenger RNA (mRNA), in the process of transcription by an RNA polymerase.

perons occur primarily in prokaryotes but also in some eukaryotes, including nematodes. An operon is made up of several structural genes arranged under a common promoter and regulated by a common operator. It is a set of adjacent structural genes whose mRNA is synthesized in one piece, plus the adjacent regulatory signals that affect transcription of the structural genes.5[1] The regulators of a given operon, including repressors, corepressors, and activators, are not necessarily coded for by that operon. The location and condition of the regulators, promoter, operator and structural DNA sequences can determine the effects of common mutations. The first operon to be described was the lac-operon in Escherichia coli.[2]
Operons are related to regulons and stimulons. Whereas operons contain a set of genes regulated by the same operator, regulons contain a set of genes under regulation by a single regulatory protein, and stimulons contain a set of genes under regulation by a single cell stimulus.
 
May 22, 2009
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I'm confused...

During transcription, in initiation, the RNA polymerase (not DNA polymerase. DNA polymerase is used in DNA replication) attaches to the promoter region of the DNA and begins to unzip the DNA into two strands.

From Wikipedia:
An operon is a functioning unit of key nucleotide sequences of DNA including an operator, a common promoter, and one or more structural genes, which is controlled as a unit to produce messenger RNA (mRNA), in the process of transcription by an RNA polymerase.

perons occur primarily in prokaryotes but also in some eukaryotes, including nematodes. An operon is made up of several structural genes arranged under a common promoter and regulated by a common operator. It is a set of adjacent structural genes whose mRNA is synthesized in one piece, plus the adjacent regulatory signals that affect transcription of the structural genes.5[1] The regulators of a given operon, including repressors, corepressors, and activators, are not necessarily coded for by that operon. The location and condition of the regulators, promoter, operator and structural DNA sequences can determine the effects of common mutations. The first operon to be described was the lac-operon in Escherichia coli.[2]
Operons are related to regulons and stimulons. Whereas operons contain a set of genes regulated by the same operator, regulons contain a set of genes under regulation by a single regulatory protein, and stimulons contain a set of genes under regulation by a single cell stimulus.
Yea sorry it's RNA polymerase that binds when you're doing transcription.

DNA polymerase binds to "transcription origins" with help of helicase, single-strand DNA binding proteins and topoisomerases, right?
 
OP
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Jul 5, 2009
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operon is only for prokaryotes or for both pro and eukaryoktes?
 
May 15, 2009
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operon is only for prokaryotes or for both pro and eukaryoktes?
It's a cluster of genes only found in prokaryotes!
 

sfrice80

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Jun 11, 2009
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It's a cluster of genes only found in prokaryotes!

Thats incorrect because its found in nematodes as well and nematodes are eukaryotes. If you want to generalize it for the DAT, its probably smart to keep it limited to prokaryotes but its also seen in some eukaryotes.
 
May 15, 2009
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Thats incorrect because its found in nematodes as well and nematodes are eukaryotes. If you want to generalize it for the DAT, its probably smart to keep it limited to prokaryotes but its also seen in some eukaryotes.
I didn't know that!
I said that based on what's mentioned in most review books. Most of them limit operons to prokaryotes. Although as you mentioned there are probably exceptions like nematodes, which are eukaryotes.

 
May 22, 2009
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I'm pretty Eukaryotes have Operons too. It's just much more complicated and involved multiple enzymes usually. It can be a far distance upstream or even downstream of the promotor, but it's definitely there.

I mean how else would you have gene regulation?
 
OP
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Jul 5, 2009
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Thats incorrect because its found in nematodes as well and nematodes are eukaryotes. If you want to generalize it for the DAT, its probably smart to keep it limited to prokaryotes but its also seen in some eukaryotes.
so it's safe to say 'operon' is only for prokaryotes only in DAT...anybody got hurt for this statement in DAT???