Genetic engineering Flashcards
Chapter 1.#
What is genetic engineering?
It refers to the techniques and processes used to directly manipulate the genomics of organisms, allow scientists to transfer specific genes from one species to another to provide the target organism with the new desired traits.
How is it possible to transfer DNA between different species?
DNA is universal.
List some examples of its application to society.
Producing desired proteins like insulin or antigens for vaccines, improving plants (pest-resistant, drought-resistant) and improving animals - such as enhanced wool or milk production.
Why is genetic engineering favourable above selective breeding?
It is significantly quicker and more reliable with enhanced specificity.
What are the three types of genetic engineering?
- Genes are taken from one organism, altered, and returned to the original organism
- Genes are transferred from one organism to another
- A specific segment of DNA is artificially synthesised and transferred to an organism
When does the recipient cell express characteristics?
When it synthesises the protein coded for by the gene.
What is recombinant DNA?
When DNA from different sources are artificially combined.
What is transgenesis?
The process by which a desired gene is transferred between organisms through three common methods.
What are the three common methods of transgenesis? (and other three less common)
TI plasmids, viral vectors and micro-injection. Electroporation, liposome fusion and gene gun.
What is a bacterial plasmid?
An accessory loop of DNA in bacteria.
What are the steps of the DNA cloning process?
- Extract DNA from target cell containing the gene of interest
- Cut the DNA using a specific restriction enzyme (this produces multiple DNA fragments with sticky ends containing unpaired bases)
- Remove plasmids from bacteria
- Cut the plasmids with the same restriction enzymes (this produces complementary sticky ends)
- The DNA fragments are inserted into the bacterial plasmids and annealed using DNA ligase (forming recombinant plasmids, one of which contains the gene of interest)
- Bacterial cells take up recombinant plasmids in a process called transformation. This involves shocking them using electricity (electroporation) or high temperatures
- All transgenic bacteria are then cultured (DNA replication and binary fission occurs, leading to many copies of modified bacteria quickly)
- This exponential growth of bacteria results in multiple copies of the gene of interest being produced (i.e DNA cloning).
What are the main steps for genetic engineering?
- Extraction of DNA containing desired gene
- Identify the desired gene
- Isolate the desired gene
- Transfer genes between species
- Organisms express gene product
What is microinjection?
The physical method of gene transfer that is often used to transfer genes to animal cells. Many copies of the desired gene are injected directly into the nucleus of a fertilised egg cell through a thin micropipette.
Describe the process of microinjection.
- Numerous quantities of the desired gene are injected directly into a fertilised ovum (egg cell) by a microinjection
- The DNA of the fertilised ovum will incorporate a copy of the injected gene
- When the organism is developing, all the cells will contain the desired gene and express the specific characteristics
What is conjugation?
The transfer of plasmids through cell-to-cell contact. Conjugation is where bacteria will replicate the plasmid and pass it onto other bacteria through a structure called a pilus.
What are viral vectors?
Viruses are protein capsules enclosing DNA molecules; they can infect organisms by injecting their genetic material into the recipient cell.
Describe the process of using viral vectors.
- Desired gene is isolated and then packaged inside a virus capsule
- The virus can thus be used to infect target cells with the desired gene
- The virus infects and reproduces inside the target cell, cloning the desired gene
What is electroporation?
It uses an electric shock to puncture small holes in the cell membrane, allowing the gene to get into the cell.
Describe the process of TI (tumour-inducing) plasmids.
- T-DNA plasmid removed from bacterium
- Plasmid is cut using a restriction enzyme
- Foreign DNA cut with same restriction enzyme and inserted into plasmid (recombinant plasmid)
- T-DNA carrying inserted gene incorporated into plant cell chromosome
- Plant cells cultured
- A transgenic plant expressing inserted gene is generated
What are some benefits of genetic modification?
- Cure genetic diseases
- Produce vaccines/hormones without side effects
- Reduce the use of pesticides which is beneficial to the environment
- More efficient food production through disease-resistant crops and faster growing stock
What are some concerns of genetic modification?
- Genes may interrupt the food chain if it escapes into nature
- Can be misused to produce ‘designer’ babies with specific ideal characteristics
- Privacy concerns; should this information be accessible to others?
- There is concern regarding the suffering of animals involved in research and tests
- There may be unknown toxic effects
- Transgenic crops may outcompete native vegetation, destroying the habitat and consequent biodiversity of an ecosystem
What is CRISPR?
Enhances the specificity, affordability and speed of gene editing.
What are the two major molecules involved in CRISPR?
- Enzyme Cas9 which acts as a pair of molecular scissors to cut DNA at specific sites
- Guide RNA which ensures that the Cas9 cuts the right spots on DNA
