Gene Therapy. Flashcards
Define gene regulation?
The ability for a gene to be turned on or off.
Define a somatic cell?
Any cell within the body that is not a sex cell.
Define transfection?
The process of deliberately inserting genetic material into a eukaryotic cell.
Define a transgene?
A genetically modified gene.
What is gene therapy?
A molecular biology tool that can be used to treat disease by modifying genes within the patient.
What kind of diseases can be treated via gene therapy?
Genetic and acquired diseases.
What process does gene therapy usually involve?
Inserting a normal gene directly into a cell.
How does inserting a normal gene into a cell help correct a genetic disease?
The normal gene will produce normal gene products and this can correct or prevent a pathological process.
How is normal DNA inserted into a malfunctioning cell?
Normal DNA is isolated from a normal cell and is then packaged into a vector and inserted into the cell.
What vector is often used for gene therapy?
A modified virus.
What is germline gene therapy?
It involves inserting a transgene into an unfertilised egg.
What are the 3 major techniques that can be used to insert transgenic genes into an organism?
Germline therapy.
Germinal therapy.
Somatic therapy.
What happens in germline therapy after the transgene has been inserted into an unfertilised egg?
The egg can be fertilised allowing the egg cell to divide and form new cells, all of which contain the transgene.
What is germinal therapy?
It inserting a transgene into a blastocyst.
In germinal therapy, which cells of the blastocyst will exhibit the DNA from the transgene?
A blastocyst is multicellular and only a single cell will take up the DNA of interest.
Therefore, only cells that are formed from this particular cell will display the transgene.
Does germinal therapy allow for all the cells of the blastocyst to exhibit the transgene?
No.
This method only allows for the transgene to be present in some of cells.
What kind of structure is created by germinal therapy?
A mosaic gonad.
Why is a mosaic gonad created by germinal therapy?
Because the transgene is not present in every cell in the body.
Are the genetic changes that arise from germline and germinal gene therapy heritable?
Yes.
Can the traits that arise from transgenic DNA be passed down to offspring?
Yes.
What does the heritabloe nature of transgenic DNA mean?
It means that any negative traits that have been corrected will not be transmitted to offspring.
Why has germline and germinal gene therapy not been carried out on humans?
As they both have issues over the ethics of inserting foreign genes into unwilling participants.
What is somatic gene therapy?
It involves introducing a transgene into a somatic cell that has been affected by disease.
What happens in somatic gene therpay once the transgene has been incorporated into the somatic cells genome?
The cell will replicate the new genetic material every time it divides.
This creates a number of cells that do not exhibit the disease and this allows for the disease to be cured.
Are the genetic changes that arise due to somatic therapy are heritable?
No.
The effects of somatic gene therapy are confined to who?
To the patient.
Will the effects of somatic gene therapy affect every cell within the body?
No.
What must happen with somatic gene therapy if the effects are to be long lasting?
The process may have to be repeated at in the future for the effects to be maintained.
What can the process of using somatic therapy to insert the DNA of interest into a cell be thought of as?
As infecting a cell with new DNA.
What are the 2 outcomes that can occur after using somatic gene therapy to infect a cell?
The creation of an integrated gene.
The creation of an episomal gene.
What is an intergrated gene?
A gene that is incorporated into the genome of the cell.
What is an episomal gene?
A gene that is not incorporated into the cellular DNA and is left in the cytoplasm of the cell.
The creation of what kind of genes are most desirable in somatic gene therapy?
The creation of integrated genes, as these cells will utilise the gene of interest to correct any cellular abnormalities.
What happens when somatic cells with an intergrated gene divide?
They will copy the gene of interest and this allows creates new cells that are free of abnormalities.
Will the abnormalities be corrected in cells that contain episomal genes?
No, as these cells can not utilise the gene of interest and this means that cellular abnormalities will persist.
How can the abnormalities cells with episomal genes be corrected?
By inserting a new gene of interest into the nucleus.
When cells containing episomal genes divide, will they copy the episomal gene?
No.
What is in vivo gene therapy?
Where normal genes are inserted into the DNA of human cells whilst they are in the body.
What is ex vivo gene therapy?
Where cells are removed from the patient and new genes are transferred into these cells.
The modified cells are placed onto growth media where they can replicate and form a collection of modified cells.
These modified cells can then be inserted into the patient.
During ex vivo gene therapy, how can scientists tell if the gene of interest has been inserted into the cells in growth media?
Via selectable markers that can show which cells have taken up the modified DNA.
What happens in in vivo gene therapy after the modified DNA has been inserted into cells?
The cells will replicate and create new cells that contain normal genes.
This allows for normal cells to replace a population of damaged or defective cells.
What is involved in the process of gene augmentation therapy?
It involves inserting a normal gene into a non-specific location within the genome.
What is gene augmentation therapy used for?
To replace a non-functional gene with a newly inserted normal gene.
What can gene augmentation therapy be used to treat?
Inherited genetic disorders that are caused by the loss of function of a gene.
What characteristic must a genetic disorder have if its effects are to be cured by gene augmentation therapy?
The condition must be reversible or this strategy will have no effect on the patient.
What specific condition is gene augmentation therapy often used to treat?
Adenosine de-aminase deficiency (ADA) which is an autosomal recessive disorder.