Edexcel A2 Biology Unit 5 (6BIO5) - 22/06/2011- OFFICIAL THREAD !

Primary response will be that you have the old Macrophages recognizing the pathogens antigens as being 'non-self', undergoes phagocytosis and the macrophage will present the antigen by becoming a APC (forms a major histocompability complex MHC)

T-helper with complementary receptors bind to APC and releases cytokines, and this stimulates clonal selection of the B-lymphocytes.

B-lymphocytes specific to that pathogen will differentiate into plasma cells secreting complementary antibodies, and of course there will be some memory cells.

Now the main thing is that, perhaps in the first infection the "taxicab will release its payload" however, when it comes to secondary infection:

The memory cells are present and can respond quickly to the same pathogen, thus reducing the chance that the second dose of gene therapy will work.

thanx but what do they mean with 'taxi cab'?? i never understood that

Blood and urine of athletes are routinely tested at every competition.Suggest why two samples are taken of each blood and urine????

1. For reliability purposes.... if they take two repeat measurements, and the results are concordant more likely that the data is representative and more likely that other people will believe the tests
2. To make sure that there wasnt any false positives or negatives

for the realibiliy why would they not repeat it with urine sample?they repeat the test with blood sample for the second............still for reliablity>
they

Stressing so much about this exam!
Does anybody know what the core practicals were in these two topics, and whether we need to know them like we did in the other exams? I can remember some of the practicals we done in class, but not whether they were core ones or not!
I'm going to trawl through the thread later, but it seems like the pre release will be based on a lot of genes, muscles and gene therapy, right?

Stressing so much about this exam!
Does anybody know what the core practicals were in these two topics, and whether we need to know them like we did in the other exams? I can remember some of the practicals we done in class, but not whether they were core ones or not!
I'm going to trawl through the thread later, but it seems like the pre release will be based on a lot of genes, muscles and gene therapy, right?

Well, I've still to revise it!
Although from what I can remember so far:
Transcription factors regulate gene expression. They normally bind to DNA at specific gene sites (different transcription factors bind to different genes).

By binding to the DNA strands they either promote or inhibit transcription of the gene. They do this by preventing the DNA strand from unwinding - RNA ploymerase therefore can't 'read' the strand, or they promote the unwinding of the strand instead and RNA polymerase is free to transcribe at a rapid rate.

Therefore, the rate of protein synthesis is eventually regulated because the amount of mRNA being created is regulated by the above.

habituation of snails, the spirometer/lung volumes one and measuring the rate of respiration of woodlice (with the soda lime and the respirometer)