Genetics 8: Gene therapy Flashcards
What is biotechnology
The manipulation of organisms or their
component parts to make useful products (for humans).
Compare genetic engineering (recombinant biotechnology) with Traditional biotechnology
- Gen eng: Manipulates DNA and RNA In vitro (lab) and then reintroduction into the living organism so control of gene expression
whereas
Traditional biotechnology is selective breeding to exploit naturally occuring mutations so no control over gene expression.
2.Gen eng: precise choice over one or few genes whereas Trad: new combination of many genes
3. Gen eng: uses genes from any species but
Trad: only gene from related species
What are the methods used in traditional biotechnology for plants
Selective breeding, cloning and mutagenesis.
Mutagenesis uses chemicals or radiation to induce mutations and thereby enhance genetic variation.
Variation in chromosome number is also used to create new plant cultivars.
What are the pros and concerns about GMO plants
Pros: can engineer them to be resistant to weedkiller. Can be resistant to certain diseases
Cons: The sanctity of nature, GMO free image, safety, public health and environmental effects.
What is “personalised medicine” and what does it mean for future generations
Where a person’s genetic profile can inform them about diseases and conditions for which they may be at risk. For future generations, there might be sequencing of genome at birth bc next generation sequencing can be $1000 .
How are genetic disorders detected through genetic tests (eg sickle cell)
- The b globin gene is amplified by PCR after a blood sample has been taken
- The PCR product is bound to a solid membrane
- The DNA is made single stranded and hybridised with a tagged probe separately for both the normal sequence and the mutant sequence
- The amount of probe determined by how much tagging they see can tell if it has hybridised or not. Dark= hybrid
How does next generation/sequencing by synthesis sequencing work –> 10 million sequences obtained simultaneously
- Genomic DNA is fragmented into 300-400 bp
- Each fragment of double stranded is isolated with a magnetic bead
- In the Oil droplet on each bead a PCR reaction takes place that amplifies the (single stranded) fragment and attached to the bead by 5’ end.
- Each bead is put into a well with lots of DNA polymerase and primers
- Solution of each of the 4 nucleotides are added to the wells sequentially and then washed off and it is repeated.
- A chemical technique is used to identify which of the four nucleotides is added.
what is 3rd gen sequencing
Nanopore
What is Crispr cas 9 and what does it do
Cripsrcas9 is a protein from bacteria to attack phages. It can make targeted deletions, insertions and single nucleotide changes in a genome. Crispr makes a ‘guide RNA’ and the Cas9 nuclease will cut any double stranded DNA that is exactly complementary to the guide RNA.
It will also trigger a DNA repair system which can knockout a gene if there is no functional gene sequence template because random nucleotides are added back. But if there is template then it can be repaired.
What are the two applications of Crispr cas 9 for scientists
- Knock out genes to study the genes functional effects
2. Insert a normal normal allele of defective gene into the somatic cells of affected tissue in Gene therapy
What is the aim of gene therapy and how was it done up until recently
Aim: to insert the normal allele of defective gene into the somatic cells of the affected tissues
- insert RNA version of normal allele into retrovirus or other viral vector
- Let virus infect bone marrow cells that have been removed from the patient and cultured.
- Viral DNA carrying the normal allele inserts into chromosome
- Patients own bone marrow is radiated to kill it
- Gen engineering cells are then injected back into the patient
What is the cons of old way of gene therapy and what is a solution
Using a virus vector meant that they cannot control where the RNA was inserted into the genome and this could potentially cause harmful effects to other genes. However solution is crispr cas9 which allows controls to replace the specific gene
What is the technological limitations and ethics of using gene therapy
- Very invasive process
- radiating bone marrow leaves patient immune system compromised
- very expensive - who will get treated
- might affect the development of fetus in unexpected ways/ long term side effects not yet known.
- could be used for gene enhancement
- Only treats single gene diseases
