Genetic engineering + Gene therapy- Module 6 Flashcards
Genetic engineering-
Genetic engineering- manipulation of an organism’s DNA to make a transformed organism.
Recombinant DNA
DNA formed by joining DNA from more than one source.
Transgenic organism.
An organism that has been genetically engineered to include DNA from another organism.
Part one of Genetic engineering obtaining DNA containing the desired gene
Need a DNA fragment that contains the desired gene isolated using restriction enzymes.
*Can isolate mRNA for desired gene and use enzyme reverse transcriptase to produce a strand of complementary DNA easier to identify desired gene. E.g beta cells in pancreas make insulin so make lots of insulin mRNA molecules.
Part 2 of Genetic engineering-Making recombinant DNA
( 4 steps)
1) Vector DNA is isolated
2)-vector DNA cut open using the same restriction enzyme used to isolate DNA fragment containing desired gene
-This means that the sticky ends of the ends of the vector are complementary to the sticky ends of the DNA fragment containing gene
3) The vector DNA and DNA fragment are mixed together with DNA ligase
-DNA ligase joins the sugar-phosphate backbones of the two bits of DNA. Process called ligation
4) New combination of bases in the DNA (vector DNA + DNA fragment) is called recombinant DNA
Part 3 of Genetic engineering- Transforming the cells
The vector with the recombinant DNA is used to transfer the gene into the bacterial host cells.
If a plasmid vector is used, the host cells have to be persuaded to take in the plasmid vector and its DNA.
This could be done by using electroporation.
Bacteriophage vectors infect the host bacteria by injecting its DNA into it. The phage DNA will integrate into the bacterial DNA.
Electroporation process
A suspension of bacterial cells is mixed with the plasmid vector and placed into an electroporator.
When it is switched on, an electrical field is created in the mixture which increases the permeability of the bacterial cell membrane (as pores open) so they take up the plasmids.
-Pores then reseal after electric pulse ends. DNA remains in cell
Technology transfer is…
is the sharing of knowledge, skills and technology.
A patent is …
a document giving you legal protection to an invention, for example a genetically modified product.
Process of creatinginsect resistant soy bean plants
1)Desired DNA isolated from Bt (bacterium containing gene that codes for a protein that is toxic to some insects) Using restriction enzymes and is inserted into the plasmid
2)plasmid put back into
3)Soybean plant cells infected with bacteria.
Desired gene inserted into plant cells DNA
=GM plant
Positive ethical issues of using GM plants
-Will reduce amount of chemical pesticides farmers use on crops which can harm the environment
-GM plants can be designed to be more nutritious
Negative ethical issues of using GM plants
-May encourage monoculture which decreases biodiverdity, making the entire crop vulnerable to disease as all grenetics are identical
-GM soybeans could interbreed with wild plants and produce superweeds - weeds that are resistant to herbicides
Negative ethical issues of using GM plants
-May encourage monoculture which decreases biodiversity, making the entire crop vulnerable to disease as all genetics are identical
-GM soybeans could interbreed with wild plants and produce superweeds - weeds that are resistant to herbicides
positive ethical issues of Pharming
Drugs are made in large quantities compared to other methods
=More available
negative ethical issues of Pharming
ETHICS
-harmful side effects for animal?
-Reinforce idea that animals are assets to use
Positive ethical issues of Using Pathogens for research
-Reduce suffering because previously untreated diseases now treated
Negative ethical issues of Using Pathogens for research
-Researchers infected by pathogen they’re researching + cause outbreak
-GM version of pathogen could convert back into original form + cause outbreak
-Biowarfare
(these are unlikely as there are strict protocalls)
Gene therapy
Gene therapy involves altering alleles to cure/ease the symptoms of genetic disorders e.g cystic fibrosis.
during Gene therapy, If disease is caused by a recessive allele a _____ _____ allele is added.
working dominant
during Gene therapy, If disease is caused by a Dominant allele, the allele is ………
silenced by adding a non-coding section of DNA into it.
Autosomal –
A non sex chromosome (in Humans chromosomes 1 – 22).
Recessive
Two copies of allele are needed to show the phenotype.
Mutation –
A change in the base sequence of DNA. Can be deletion, addition or substitution.
Gene
A section of DNA that codes for a polypeptide.
Gene Therapy Can be _____cell or ____ ____.
somatic or germ line.
How can we insert DNA into a cell?
Use a vector!
Plasmids
Virus
Liposomes ( spheres made of lipids)
Somatic cell therapy
Involves altering alleles in body cells, particularly those most affected by the disorder.
It does not affect the offspring
E.g In CF, somatic therapy targets the epithelial cells lining the lungs.
Germ line therapy
Altering the alleles in the sex cells. Means that every cell of any offspring produced will be affected by gene therapy so won’t inherit the disease.
Currently, germ line therapy is illegal in humans.
4 Advantages of gene therapy
Could prolong lives of people with life-threatening genetic disorders
Can give people with genetic disorders a better quality of life- eases symptoms
GL therapy would allow carriers of genetic disorders to conceive a baby without disorders
Could decrease the number of people with disorder in population less people require treatment so less strain on NHS
any 4 from Disadvantages of gene therapy
Body could start an immune response against vectors
Allele could be inserted in the wrong place, causing more problems e.g cancer
An inserted allele could get overexpressed, producing too much of the protein which can cause other problems
Effects of treatment may be short-lived with somatic therapy so may have to undergo multiple treatments
May be difficult to get the allele into specific body cells
Could potentially be used in ways other than medical treatment e.g anti-ageing treatments
Potential to do more harm than good
Expensive- could it be better spent on treatments that have passed clinical trials?
explain how scientists can determine the success of inserting the plasmid into the bacterium
Use of a marker gene
(genes for) fluorescence
(examine fluorescence under) UV light
or
Antibiotic resistance gene
Grow on agar containing antibiotic
what needs to be done with the mRNA tha codes for insulin in order for the rest of the genetic modification to take place
-Make single stranded DNA/Complementary DNA
-Using reverse transcriptase
-Make double-stranded DNA using DNA polymerase
state one valid concern that people have about the GM of bacteria
(increase in antibiotic) resistance
explain how inserting a new gene into a chromosome could affect her functioning of other genes in that chromosome
-Frameshift
-Altered triplets
-Adjacent/nearby genes (on same chromosome) switched on/off
-idea that new gene could disable a functioning gene if inserted into it
Huntington’s disease is lethal and caused by a dominant allele that codes for a protein huntingtin
Suggest why gene therapy is unlikely to work as a treatment for Huntington’s disease
protein/ Huntingtin still synthesized/present
*( Alleles are dominant because they synthesize a particular protein and would continue to do so in presance of healthy allele
Huntington’s disease is lethal and caused by a dominant allele that codes for a protein huntingtin
Suggest why gene therapy is unlikely to work as a treatment for Huntington’s disease
protein/ Huntingtin still synthesized/present
*( Alleles are dominant because they synthesize a particular protein and would continue to do so in presence of healthy allele
