general questions for the big day...

[golden]

In order for the transcription to take place, the enzyme that synthesizes RNA, known as RNA polymerase, must attach to the DNA near a gene. Promoters contain specific DNA sequences and response elements which provide a secure initial binding site for RNA polymerase and for proteins called transcription factors that recruit RNA polymerase. These transcription factors have specific activator or repressor sequences of corresponding nucleotides that attach to specific promoters and regulate gene expressions. - Wikipedia (Promoter (biology)).

How can promoters (the actual promoter itself) regulate gene expression?

[bar0029]

promotors don't themselves regulate gene expression
instead: it provides a binding site for dna signalling proteins, hormones, enzymes, etc. to bind to which can switch the gene on or off.

[golden]

promotors don't themselves regulate gene expression
instead: it provides a binding site for dna signalling proteins, hormones, enzymes, etc. to bind to which can switch the gene on or off.

In my notes which I wrote and I remember hearing/reading it from some source, promoters (quote from my notes) 'Are involved in regulating and in some sense the expression of a gene'. But I also have another definition which states that it 'helps with the initiation of transcription - RNA polymerase attaches itself to it during transcription.

I recall that a promoter can be placed in plasmids (etc.) as well to help regulate genes. But I'm not sure if these promoters are the same or the name for another aspect that is involved in that case as above (plasmids).

[Russ]

does anyone know how to do Q10 of MC from biol exam 2005.

Look at the offspring give. Recognise that there are two classes, recombinants and parentals. It's implied that the dwarf/pear plant was homozygous recessive, so only the gametes of the heterozygote matter.

Based on the numbers, parentals are tall/pear and dwarf/spherical
Thus the arrangement on the parental chromosome must be:

Dp
__
dP
Therefore, B

[bar0029]

promotors don't themselves regulate gene expression
instead: it provides a binding site for dna signalling proteins, hormones, enzymes, etc. to bind to which can switch the gene on or off.

In my notes which I wrote and I remember hearing/reading it from some source, promoters (quote from my notes) 'Are involved in regulating and in some sense the expression of a gene'. But I also have another definition which states that it 'helps with the initiation of transcription - RNA polymerase attaches itself to it during transcription.

I recall that a promoter can be placed in plasmids (etc.) as well to help regulate genes. But I'm not sure if these promoters are the same or the name for another aspect that is involved in that case as above (plasmids).

im 100% sure that the promotor provides a binding site, and what you've said above is exactly what im talking about because e.g. with the plasmid thing, the transgene will not be transcribed without the promotor because the promotor provides the binding site of which RNA polym. can bind to initiating transcription.
if that makes sense lol

[golden]

Maybe back then as I was writing the notes I had heard that promoters can act as regulators as a mutated promoter can stop gene expression. Thanks for the explanation.

[onerealsmartass]

ummm my definition of a promoter - non coding base sequences that signal the start of the signal, thus the binding site for RNA polymerase.

correct me if im wrong (:

[TrueLight]

binding of proteins like transcription factors etc can regulate transcription by binding to promoter regions or near them but the actual promoter sequence doesn't do anything unless something binds to it ...
but yes the promoter is where the rna pol binds ... and yes in eukaryotes you need different transcription factors to bind to different regions of the promoter for rna pol to bind...

[bar0029]

dna binding proteins are only in eukaryotes however
whereas in prokaryotes to regulate genes they have repressor molecules as seen in the lac operon

[Russ]

They have other types of moderation as well, the lac operon is just one example

[bar0029]

hence the e.g.

[Russ]

Your post doesn't have an e.g. in it, it sounds as if repressors are the only system

[TrueLight]

only found in eukaryotes?
dna binding protein= a protein that binds to dna
whats a repressor protein?

[bar0029]

i meant eg. by as seen
and repressor proteins are molecules such as tryptophan, you dont need to know their names specifically, it will be given in the question

[TrueLight]

tryptophan molecules are the corepressor
trp repressor is the repressor