Anyone studying A2-level Edexcel Biology A Salters Nuffield??

How would you link GMOs to rates ??
For GMOs I was thinking more along the lines of describe ho you would genetically modify a plant,or bacteria or animal.
For the brain,I bet we will have one of the scanning techniques MRI,fMRI,CT and PET.
I would bet money on PET,since it is new spec.
Spirometer may not come up since it was mentioned in paper 2.
We have not done much on the heart so far ,I can easily see combination of what we learned about the heart from AS and A2 being on the paper,along with a few graphs.

Depressors are to do with muscles that contract to pull down part of the body such as the diaphragm to help increase the volume of air to the lungs.
Repressors are to do with slowing down the rate of transcription.

- At normal temperatures the thyroid hormone receptor acts a repressor so decreases the rate of transcription for the protein that can raise metabolic rate.
-At colder temperatures thyroxine binds to the thyroid hormone receptor, together this complex causes it to act as an activator which increases/promotes the rate of transcription for the protein that raises metabolic rate thus increasing the temperature of the body.

@bobby147 also you may have written in the part where you quoted me. Check the blue box in your comment above (1180). Half way through the quote you wrote in there by mistake "oh yeah,maybe thats why you use alcohol !I should of thought that thanks." Should probably edit that

Yes I bet PET scans will come up too. Which is typical because it's the one I know least about. Besides the fact that it gives images of the brain in real time and it uses a radioactive tracer I'm not actually too sure how it works! How does the radioactive tracer being absorbed in the tissues of the body build up a picture of the structure and function of the brain in real time?

Oh ,I had no idea there were depressor muscles.My notes puts inhibitors/depressors decrease the rate of transcription,fair enough.
I still think my explanation stands.If you are slowing down the rate of transcription,you are still making proteins,so it will bind to the promoter region.
If no protein is made at all,then the transcription factor will bind to the operator region.
Edit:This seems to be getting a bit complicated.The internet maintains transcription factors can bind to the operator while the book doesnt.I guess this is another thing we are taught swishy swashy at A level.
I think we should just say operator for lac repressor,promoter for everything else.I blame Edexcel for being crap at explaining this.
Ok,I will edit .

Radiotracers emit positrons,which is antimatter counterpart to the electron.
When a positron collides with an electron,it prroduces gamma rays which is picked up by the detector and is displayed on a computer.It the more look like this

What you see in a PET scan is NOT the radiotracer ,it is rather the gamma radiation produced by positrons and electrons colliding.
The more active the area of the brain,the more blood flow and so more radiotracer will build up in that area.Hence more gamma radiation will be emitted from that area,so the active areas of the brain will be the brightest.

Yes if a question mentions anything about bacteria (E.coli), $\beta$ - galactosidase, or lactose then you know you will have to mention the lac-operon model and how the operator region (as well as the promoter region) works.

For Eukaryotes I think we should stick to only mentioning the promoter region just to be safe.

Exactly! If a repressor/inhibitor binds to the DNA (at the promoter region) then the rate of transcription is decreased, but there are still proteins being made just as a slower rate (not as much is being produced).



Amazing!! That has cleared up so much!! Any chance you're hoping to study Radiography at University?

Yes if a question mentions anything about bacteria (E.coli), $\beta$ - galactosidase, or lactose then you know you will have to mention the lac-operon model and how the operator region (as well as the promoter region) works.

For Eukaryotes I think we should stick to only mentioning the promoter region just to be safe.

Exactly! If a repressor/inhibitor binds to the DNA (at the promoter region) then the rate of transcription is decreased, but there are still proteins being made just as a slower rate (not as much is being produced).


Amazing!! That has cleared up so much!! Any chance you're hoping to study Radiography at University?

Out of interest, what marks have people been getting in Specimen Paper 3?

I got 65%, marked fairly harshly

67% here :/ which for all we know be an A

Haha you have a lotttt of knowledge bobby, I thought for eukaryotes there wasn't a promoter or operator site, I thought RNA polymerase just binds to a start codon/start of a gene. Is this incorrect?

Eukaryotes do have a promoter and operator site.
Promoter is just a fancy word for where transcription factors bind to near the start of the gene they target.
Operator is just the word for where repressors bind to regulate gene expression by
supressing it.
RNA polymerase binds to the promoter region which is near the start of the gene.
Your are right with the start of the gene ,by mentioning promoter region,you are just being specific by mentioning where it takes place.

What are people doing to revise? Specimen papers, learning practicals and EMPAs maybe? The fact that the whole spec is being tested is so unfair

just to clarify for everyone promoter region is for eukaryotes and operator is for prokaryotes

Ok guys.Paper 3 on Monday.
Paper 1 was fine but Paper 2 was tough.Lets pull through and smash this Paper 3 since its 40 percent of our A level.
Ill be on this thread most of the time or on the chemistry thread.I will also be up here very late.
Lets help each other and do this !!

40%??? is it more than paper 1 and 2? i thought it was 33%

just to clarify for everyone promoter region is for eukaryotes and operator is for prokaryotes