7- gene technology Flashcards
producing recombinant DNA
The production of recombinant
DNA involves the joining of DNA from two different sources.
role of restriction endonucleases
They recognize specific DNA sequences and cut the DNA at these sites, leaving sticky ends, thus allowing for the insertion of foreign DNA.
role of DNA ligase
They join the ends of two DNA fragments produced by restriction endonucleases by catalysing the formation of phosphodiester bonds between the DNA molecules.
steps of producing recombinant DNA
- DNA extraction: DNA is extracted from both the donor and the host.
- Cutting of DNA: The extracted DNA is cut into fragments using restriction endonucleases. The same enzyme is used to ensure the ends of the DNA fragments are complementary.
- DNA ligation: The donor DNA fragment is inserted into the host DNA using DNA ligase, creating a recombinant DNA molecule.
- Insertion: The recombinant DNA is introduced into host cells, which are then allowed to multiply, creating multiple copies of the recombinant DNA.
applications of recombinant DNA technology
• Production of genetically modified organisms.
• Gene cloning.
• Manufacturing of biopharmaceuticals.
• Study of gene function.
• Production of therapeutic proteins.
• Development of genetic tests.
insertion of recombinant DNA into cells- viral vectors
• Viruses have a natural ability to insert their DNA or RNA into host cells.
• A portion of the virus’s genome is replaced with recombinant DNA.
• The modified virus infects the host cells and delivers the recombinant
DNA.
insertion of recombinant DNA into cells- liposomes
• The small lipid droplets coat and surround plasmids with recombinant
DNA.
• They cross the cell membrane via endocytosis and enter the nuclear membrane.
insertion of recombinant DNA into cells- gene guns
• They bombard cells with tiny particles of heavy metals coated in recombinant DNA.
• The DNA-coated particles penetrate the cell membrane, delivering DNA to the cell.
insertion of recombinant DNA into cells- electroporation
• Electricity is used to make pores in the cell membrane of target cells.
• The cell takes up the recombinant
DNA and incorporates it into their own genome.
antibiotic resistance marker genes
• These genes confer resistance to specific antibiotics.
• They are typically included in the recombinant DNA construct.
antibiotic resistance marker genes method
• After insertion, cells are grown on a medium containing the antibiotic.
• Only cells that have taken up the recombinant DNA will be able to grow, while the non-transformed cells will be killed by the antibiotic.
replica plating
This is used to transfer colonies of cells from one agar plate to another identical plate, maintaining the same spatial pattern of colonies.
replica plating method
• The source plate has colonies. All bacteria in a colony are genetically identical.
• An imprint is taken by gently pressing down with a sterile piece of filter paper.
• The filter paper is pressed onto the surface of the replica plate.
knockout mice
• Knockout mice are mice in which specific genes have been intentionally deleted.
• They serve as a crucial animal model for studying gene function.
creation of knockout mice
• A specific gene is replaced or disrupted by an artificial piece of
DNA, through homologous recombination in embryonic stem cells.
• These genetically modified cells are introduced into mouse embryos.
• The resulting mice are chimeras, containing both modified and unmodified cells.
• Breeding them eventually produces offspring where all cells have the knocked-out gene.
how to use knockout mice to study gene function
• By observing their phenotype, the function of the knocked-out gene can be inferred.
• Any differences can be attributed to the lack of the knocked-out gene.
advantages of using knockout mice
• Physiological relevance: Mice share a high degree of genetic and physiological similarity with humans, making them a useful model for understanding human disease.
• Specificity: Knockout technology allows for the study of single genes, providing a precise way to investigate their roles in health and disease.
limitations of knockout mice
• Lethality: Some gene knockouts can result in embryonic lethality, preventing the study of gene function in adult mice.
• Compensation: Other genes may compensate for the loss of the knocked-out gene, obscuring the gene’s true function.
• Ethical considerations: The creation and use of knockout mice raises ethical considerations, including animal welfare and the justification for using animals in research.
gene modification of soya beans
This is often achieved through the introduction of foreign genes into soya beans using techniques like
Agrobacterium-mediated transformation or gene gun technology
herbicide resistance
• Glyphosate, a common herbicide, kills plants by inhibiting an enzyme unique to plants.
• A gene conferring resistance to glyphosate is introduced to soya beans.
• This allows farmers to spray their fields with glyphosate, killing weeds but leaving genetically modified soya beans unharmed, thus improving yield.
polyunsaturated fats in soya oil
• Are susceptible to oxidation, which makes it rancid.
• Have linoleic acid that is readily oxidised to produce trans fats.
Trans fats are harmful to health as they raise levels of LDLs and lower levels of HDLs, thus increasing the risk of heart disease.
genetic modification affect on polyunsaturated fats in soya oil
• Lower the proportion of linoleic acid.
• Increase the proportion of oleic acid.
this improves:
• Oxidative stability → the shelf life and heat stability of soya oil.
• The nutritional value of soya oil.
advantages on genetic modification of crops and other transgenic processes
• Improved yield: GM crops can be engineered to be more resistant to pests, diseases, and harsh
environmental conditions, potentially increasing agricultural productivity.
• Reducing post-harvest losses:
Some GM crops are engineered to have longer shelf lives, reducing food wastage.
• Nutritional enhancement: Genetic modification can be used to improve the nutritional content of crops, such as increasing vitamin or mineral content.
• Potential to address nutritional deficiencies.
• Potential to address food security.
disadvantages on genetic modification of crops and other transgenic processes
• Environmental impact: Concerns include potential effects on non-target species (such as butterflies and bees), development of
resistance in pests, and gene flow to wild relatives of GM crops, which could affect biodiversity.
• Health concerns: Some people worry about the potential impact of consuming GM foods on human health, despite scientific consensus that GM foods are safe to eat.
• Economic and social issues: Critics argue that GM crops can lead to increased dependence on certain agrochemicals and promote a system of agriculture that favours large corporations, potentially disadvantaging small farmers.
