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Module 6: Genetic change - Coggle Diagram
Module 6: Genetic change
Mutations
Mutagens
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Chemical Mutagens
- Chemicals that cause mutations if cells are exposed to them at high frequencies.
- Chemical mutagens cause a change in DNA that alters the function of proteins.
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Types of mutations
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Chromosomal
Deletion
-Occurs when a section of DNA is removed and not replaced. Leads to a reduced number if genes in the Chromosome
Often the result of exposure to heat, radiation or viruses. Generally fatal
Duplication
Involves replication of a section of a chromosome that results in multiple copies of the same genes o that chromosome
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Inversion
Involves a section of the Sequence breaking off the chromosome, rotating 180° and reattaching to the same chromosome. May involve as few as two bases or may involve several genes.
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Variation related to fertilisation, meiosis and mutation
Biotechnology
Past, present and future biotechnolgy
Past uses
Domestication of plants and animals
- Domestication began over 10,000 years ago.
- Rice, barley and wheat were some of the first domesticated plants.
- Wild animals were tamed to provide milk or meat.
- There were also used to help with farm duties such as ploughing and guarding the farm.
Fermentation
- Led to improvements in preservation and an increased range of foods including beer, wine, cheese, yoghurt and soy products.
- Process where microorganisms (yeasts, moulds and bacteria) convert sugars into energy.
Agriculture and Aquaculture
- Agriculture and aquaculture are used for selective breeding of crops and animals.
- Aquaculture is the farming of aquatic organisms such as fish, molluscs, crustaceans and aquatic plants.
- Has led to improvements in quality and quantity of food.
Medical Uses
- Some traditional medicines used organisms. An example of this is in ancient Egypt used honey for respiratory infections or for wounds. The honey acts as an antibiotic.
- The Chinese used mouldy soybeans curds to treat boils.
- Recent developments include antibiotics, vaccines and drugs such as aspirin.
Selective breeding
- Early forms of selective breeding started with mating organisms with desirable traits to enhance these traits in their offspring.
- Corn is one example of selective breeding as it has been enhanced to make it a better food source.
- Dog breeds are another example. all of the different dog breeds have resulted from selective breeding. Dogs have been bred for specific jobs and to enhance traits such as size, shape, agility and colour.
Present uses
Gentically engineered cotton - Herbicide Tolerance
- Pests feed on parts of the developing cotton called squares, blooms and bolls.
- Bt cotton includes a gene from Bacillus thurengeiensis which contains a protein that is only activated in the high pH insect gut.
- When it is activated, it produces a toxin that naturally kills pests.
Golden Rice
- Golden rice was scientifically created to improve human health, particularly in underdeveloped countries.
- Golden rice contains beta-carotene which is needed for Vitamin A production.
- Three genes were used to create Golden Rice, 2 from daffodils and 1 from a bacterium that is capable of catalysing 4 biochemical reactions.
Salt Tolerant Wheat
- Less than 20% of the Earth can be used for agriculture.
- However, some crops have been genetically altered to allow them to grow in conditions like high salinity, cold and drought.
- The discovery of the genes responsible for sodium uptake has led to plants being able to grow in high salt environments.
Biofuels
- Agriculture provides the feedstocks for fermentation and refining of bio-oils, -diesels and -ethanol.
- Genetic engineering is being used to create better feedstock for a more efficient and higher output of the resulting fuel products.
- This reduces the costs for the productions of bio-fuels.
Improved Taste, Texture or Appearance of Food
- Can be used to slow down spoilage rate of food.
- Fruit can ripen for longer, makes transport easier.
- Improving these factors will also extend the useable life of the fruit.
Example: Tomato's - These were the first GMO food product and it delayed the ripening, making it transportable.
Genetically Modified Animals
- Atlantic Salmon is the only animal that has been genetically modified and used for food.
- They have a growth hormone gene from chinook salmon that makes them grow much faster than standard Atlantic salmon.
- They also consume 20% to 25% less food per gram.
Future uses
DNA Sequencing
- Advances in DNA sequencing and technologies have led to developments of synthetic biology.
- Can read and write longer DNA sequences.
- This could allow for genetic background screening to be used to make personally tailored drugs.
Medical Applications
- Improvements to health, quality of life and length of life.
- Help to lessen stress on families with sick family members.
- Biotech will allow for greater understand of new materials for medicine .
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Social, economic and cultural contexts on a range of biotechnologies
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Genetic technologies
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Cloning
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- Begins with SCNT, somatic cell nuclear transplant, a process which removes a single set of chromosomes from the egg cell and replaces them with the nucleus of a somatic cell taken from the organism to be cloned.
- The egg cell is then allowed to divide in a process like natural fertilisation
- Once the embryo has developed, it is transferred to the uterus of a surrogate mother.
- Following gestation, an individual identical genetically to the organism from which the somatic cells were taken is born.
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Efficiency and ethics of whole organism cloning
- An ethical concern in the process of whole organism cloning is the quality of life and the shortened lifespan of the cloned animal, a likely reason for this is the shortened telomeres on chromosomes.
- The same techniques used to clone animals could be applied to clone humans, which raise issues about morality and religious, legal and social concerns.
- Religious argument that cloning is wrong as it means that humans are acting as God
- Reproductive cloning is an expensive procedure.
Advantages
- In agriculture it may be advantageous in that the ideal hybrid can be obtained and reproduced identically. characteristics bred can be controlled fully.
- Shorter timeframe for reproduction of those ideal characteristics.
Disadvantages
- Genetic diversity is reduced
- The combinations of certain genes become more frequent in a population. This is an issue as natural gene combinations that are not selected and thus disappear from a population.
- An identical population is less likely to survive sudden environmental change
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Plant cloning is achieved through the use of cutting and grafting techniques, where a section of a plant is cut/grafted and then repotted in another pot. When the new plant grows, it will be genetically identical to the original. This method is used both commercially and in home gardens.
Gene cloning is achieved by incorporating a gene into a plasmid, which is then introduced into a host and self-replicates, creating more copies of the gene. The two main techniques used for gene cloning are:
- In vitro gene cloning by PCR
- In vivo gene cloning via vector (plasmid or viral DNA)
Preparing a gene for cloning
- The target double stranded DNA of a gene from a eukaryotic organism, containing introns, is extracted.
- The process of transcription creates primary RNA molecules, as is normal in the process of gene expression.
- The introns are removed by restriction enzymes to form a mature mRNA that codes for the making of a single protein.
- The mRNA is extracted from the cell and purified
- Reverse transcriptase is added which synthesises a single stranded DNA molecule complementary to the mRNA.
- The second DNA strand is made by using the first as a template, and adding the enzyme DNA polymerase.
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This is similar to the natural process in which embryo twinning happens, in that the embryo splits into two in a laboratory petri dish.
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Benefits of using GT in agricultural, medical and industrial applications
Agricultural
- Allows for manipulation of the genome of plant/animal species in a variety of ways:
- Crop and animal species that are better suited, and able to thrive, in a hostile environment like drought or high salinity soil
- Pest resistant crops (Bt cotton)
- Transgenic organisms that increase productivity in low-quality areas and reduce post-harvest losses.
- GM plants that have increased vitamins/minerals, such as golden rice.
- GM animals that grow larger and faster, increased output rate.
Medical
- Has the potential to influence medical care through individualised treatments
- Reduce costs related to medicine and treatment through recombinant DNA technology (e.g, spider goats)
Industrial
- GM plants have the potential to replace non-renewables (plastics, fuel, paints) with environmentally friendly alternatives.
- Recombinant DNA technology has the ability to rapidly produce large quantities of enzymes, biological catalysts that have been widely used in food production & brewing for 6000 years. In modern times, this has the potential to enhance dairy production with enzymes targeted for specific substrates.
- GM plants and bacteria can be used to absorb heavy metals and other toxic materials from contaminated sites rapidly, such as in cleaning oil spills, or in remediation of land surrounding mines and other industrial sites, aiding in local ecosystem restoration.
Mutation, gene flow, genetic drift and gene pool