15. Manipulating Genes In Organisms Flashcards Preview

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What barriers did scientists face in gene transfer?

๐Ÿ”น genes are normally transferred from parent to offspring and remain within the species.
๐Ÿ”น transfer of genes between species under natural conditions is not possible due to the species barrier, members of different species cannot mate and gametes of different species cannot fuse together.


GMOs definition

Organisms whose genome contain heritable changes created through the use of genetic engineering technology


Examples of gene alteration

The addition of a gene or a segment of DNA
Switching genes on or off
The silencing of a gene so that its function is lost
A foreign gene or DNA segment is added to the genome


Transgenic organisms

Organisms that carry in their genomes one or more genes artificially introduced from another species


Mice micro injection

๐Ÿ”น DNA of the gene concerned is injected into the fertilised egg of a mouse at a stage when the male and female pronuclei have not yet fused. Produces some mouse eggs with one or more copies of injected DNA that has randomly integrated into their genomes.
๐Ÿ”น a number of eggs are implanted in a surrogate female mouse, and life mouse pups will be born 19 days later.

๐Ÿ”น DNA micro injection of eggs is used when the aim is to add a gene to create Gm mice (eg. Human growth hormone)


Mice embryonic stem cells

๐Ÿ”น Silencing of a gene is achieved by creating a gene that is homologous to the target gene but which carries a defect in its base sequence that makes it non functional.
๐Ÿ”น This defective DNA sequence is injected into an embryonic stem cell and in some cells the defective gene replaces the functional target gene by recombination.
๐Ÿ”น The target gene in those cells is silenced or knocked out

๐Ÿ”น To silence or disable a specific target gene in order to identify its function by seeing what happens when the gene is inactivated.


Atlantic salmon

๐Ÿ”น First GM animal approved for human consumption. It has growth hormone gene from a chinook salmon, a promoter gene and terminator sequence from ocean pout (an eel like fish).
๐Ÿ”น To avoid interbreeding with native species the eggs are made sterile.

๐Ÿ”น To create salmon that can reach maturity in a shorter time frame. It is estimated that the time to market was reduced from three years to 18 months.



๐Ÿ”น The production of human recFSH occurs in transgenic hamster cells. These cells have been genetically engineered so that they contain the human gene that controls production of FSH.
๐Ÿ”น recFSH is made in larger quantities, it's supply more reliable and pure than urine derived product.

๐Ÿ”น Recombinant FSH is made available to women who cannot produce their own FSH


Goats and cows

๐Ÿ”น Some research has involved the production of transgenic cows and goats whose cells carry human genes for specific protein products.
๐Ÿ”น If these genes are expressed in the milk produced by these transgenic mammals, they function as mini pharmaceutical factories to produce particular protein products

๐Ÿ”น Cows produce human protein, serum albumin
๐Ÿ”น Goats produce protein which prevents blood clotting used in heart surgery.


Agrobacterium mediated uptake of DNA

๐Ÿ”น In nature these bacteria infect plants by inserting their ti plasmid into plant cells where a segment of the bacterial DNA is transferred into the plant genome causing diseases such as crown gall disease.
๐Ÿ”น Foreign DNA inserted into plasmid t-DNA region and bacteria modified to make them harmless and non tumour produced.


Ingard cotton

๐Ÿ”นThese cotton plants were genetically engineered to include the cry1Ac gene from bacterial species Bacillis thuringiensis. The cry1Ac gene encodes a protein, known as Bt that acts as an insecticide.
๐Ÿ”น Bt insecticide is non toxic, has a narrow target range and is not a contact insecticide- must be ingested by caterpillars to take effect.

๐Ÿ”น Bt insecticides are highly effective against the leaf feeding larvae of the cotton bollworm, major pests of the crop


Roundup ready canola

๐Ÿ”น The gox gene, from the bacterial species ochrobacterium anthropic, was engineered into canola plants using agrobactium as a vector.
๐Ÿ”น The gox gene encodes an enzyme that breaks down glyphosate, the active ingredient of roundup herbicide, into a harmless product.

๐Ÿ”น Spraying canola crops with this herbicide kills weeds and other plants that lack the gox gene but leaves Gm canola plants unaffected.


Gm tomatoes

๐Ÿ”น Genetic engineering of tomatoes involves silencing genes that are induced by the ripening hormone ethylene.
๐Ÿ”น suppression of these genes using a technique known as RNA interference

๐Ÿ”น delay ripening, reduce the rate of softening and extend the shelf life of tomats


Blue carnations

๐Ÿ”น The production of a blue carnation involves silencing some genes involved in the biochemical pathway of pigment production using RNAi. It also involves the addition of genes from a pansy and an iris


Golden rice 2

๐Ÿ”น Genome of golden rice variety has been genetically engineered by insertion into the ride genome of two additional genes into the pathway for the biosynthesis of carotene and the addition of a promoters sequence that keeps the pathway active in the cells of the rice endosperm.
๐Ÿ”น the genes added are PSY gene from daffodil which codes the enzyme phytoene synthase. Crti gene from soil bacterium which encodes the enzyme phytoene desaturase, catalyses multiple steps in the synthesis of carotenoids up to lycopene.

Purpose: provides beta carotene which can be converted to vitamin a. Lack of which is major cause of preventable blindness in children, death from infection.


Social implications of Gm crops

๐Ÿ”น Increased food supply, nutritional content and food quality
๐Ÿ”น Expanded range for growth of agricultural species
๐Ÿ”น Access to the technology, social equality/inequality
๐Ÿ”น Labelling and consumer choice
๐Ÿ”น Patents and pricing, control of access by biotechnology companies
๐Ÿ”น Costs to farmers


Potential benefits of gmos

1. Increase in crop yields, crops with more nutritional value and shelf life.
2. Decrease in use of pesticides, herbicides and animal remedies
3. Production of crops that are drought resistance or salt tolerant
4. Improvement in the health of the human population and the medicines used to achieve it
5. Development of animal factories for the production of proteins used in manufacturing, the food industry and health


Potential risks of GMOs

1. Possible uncontrolled spread of transcends into other species of plants or animals
2. Concerns that the release of gmos into the environment may be irreversible
3. Animal welfare and ethical issues. Gm animals may suffer poor health and reduced life span
4. Gmos may cause the emergence of pest, insect or microbial resistance to traditional control methods.
5. May create a monopoly and dependence of developing countries on companies who are seeking to control the worlds commercial seed supply.