A2 Biology OCR June 2015 Revision Thread

I've literally just woken up from a 20 minute turned 2 hour nap so if this is jumbled then I'm sorry haha.

A gene therapy is a therapeutic technique where the functioning allele of a particular gene is placed in the cells of an individual lacking in the functioning alleles of that particular gene.

Somatic Cell Gene Therapy has two types:
Augmentation (adding genes) is where a faulty allele for a gene may lead to the organism being unable to synthesise an important protein. Augmentation is where a functioning copy of the gene is inserted, and the protein can now be synthesised.
Killing cells is where cancerous cells can be engineered to produce a particular protein (e.g cell surface antigens), causing an immune response. This may lead to a new way to treat cancer.
It must be repeated regularly as it is a short term treatment as the specialised cells containing the gene will not often divide to pass on the allele.
It is difficult to get the gene into the genome in a functioning state. Liposomes have been trialled to do this, as they are made from the same lipid bilayer as the cell membrane, and can therefore pass straight through. Genetically modified viruses have also been tried but the host becomes immune to them so the cell will not accept the vector on following treatments.

Germline Cell Gene Therapy
The germline cells are the sex cells, sperm and egg, but this therapy can also work for zygotes too.
The functioning allele is introduced into germline cells so all cells derived from the germline cells will have a copy of the functioning allele. This means the patient could potentially pass on this allele to their offspring.
This, however, is considered unethical in humans because there could be unintentional changes that may damage the embryo, it raises ethical issues of whether we should genetically engineer embryos, we could interfere with human evolution in ways we do not know.

If there's anything incorrect, feel free to correct me anyone. I hope this helps

Hey guys. I was just wondering. How far is everyone with revision for F214 and F215?

Hey guys. I was just wondering. How far is everyone with revision for F214 and F215?

How do auxins cause cell elongation? Could someone please give a detailed response as the textbook is pretty vague with the detailsIf anyone's started past paper questions - what kinds of questions have you come across so far about auxins/ plant hormones in general?

Is there any revision packs or really good techniques to get full makrs?

It's actually surprisingly ok! You could honestly learn it on your own tbh

do we need to know sickle cell anaemia in detail? and what do we need to know about homeobox genes? so much to learn so little time

homeotic codes for body plans and are similar through multiple organisms (fungi, drosophila)
Homeotic genes have homebox sequences, which code for the transcription factor (homeodomain) that that binds to the operator.
It's the homeodomain that binds to the operator of the gene that acts as a repressor/activator.

If anyone has anymore to say or corrections to that, please add some in

Okay so I can't remember anything about chromosomes, where are they located in the cell lol?
diploid and haploid numbers, what does 2n and n mean?
Someone briefly explain all of that, would be fab

Chromosomes are found in the nucleus of the cell.
Haploid - half the number of chromosomes found in a normal cell, hence n. For example, in sperm and egg cells there are 23 chromosomes as they are half of the 46 chromosomes found in a normal cell.
Diploid - having a normal number of chromosomes in a cell, i.e a full set. This is where the 2n comes from as for normal human cells, it's 46 (which as you know, is double 23 so n must be 23 in the case of humans).

Hope this helps