2020 Biology HSC Gentic-Change-Genetic-Technologies-Notes PDF

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2020 Biology HSC Gentic-Change-Genetic-Technologies-Notes...

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Genetic Technologies Processes and Outcomes of Reproductive Technologies Selective breeding involves mating a male that displayed at least one desirable characteristic with a female that displays another, in the hope that some offspring will inherit the desired traits from both parents. Offspring with both desirable traits are then selected for further breeding. Disadvantages- potential of inheriting desirable and undesirable traits together that might cause issues. E.h. hybrid cows from Friesian x Jersey might grow large udders→ making walking difficult and causing ulcers. It is also a time consuming and costly method, involving transport and such.

Artificial insemination- involves collecting sperm from a chosen male and artificially introducing it into several selected females. Mechanical collection → stored in straws → frozen and chilled in liquid nitrogen → thaws and placed in a ‘gun’ → gun is inserted into vagina. Advantages Transporting overcomes moving large animals, while being cost-effective and reducing the danger to animals of injury. Many females can be inseminated and so one male can sire offspring with several females. Due to freezing, offspring can be produced years after death. This technique is also used in conservation, by preserving populations. Semen evaluation, and also choosing the best time for conception. Prevents disease as well. Disadvantages It is costly due to specialised equipment and is also time consuming. It can also potentially injure the female and most of all, reduce genetic diversity within populations throughout the world, since favourable traits are more represented but there is an increased susceptibility to disease for a larger proportion of the population. Artificial pollination Process- involves removing stamens of a flower and dusting the pollen onto, either stigma of the same flower/another flower on the same plant (self-pollination), or a flower on a different plant (cross-pollination). This enables the creation of new varieties of plants, but can lead to a reduction in biodiversity.

Advantages- greater control of alleles. Artificial population can also increase genetic variability due to creation of hybrid species; new allele combinations are introduced into the gene pool e.g. Purple Straw 14A and Yandilla created Federation. Disadvantages- compared to insect pollinated plants, hand-pollinated plants had smaller fruit and lesser seed germination rates. Due to declining bee populations, drone pollinators with sticky surfaces are being looked at for replacements. In vitro fertilisation - differs from artificial insemination in the sense that an egg is fertilised by sperm outside the mother’s body (usually in Petri dish). Fertilisation → zygotes are cultured to early developmental stage → transferred into biological mother or stores in liquid nitrogen. Often used when there is decreased fertility in one or both of the parents. Genetic Diversity is reduced due to production of large numbers of viable embryos from a small selection or parent animals. Genes for infertility- are inherited by offspring, thus breeding infertility into a population due to reproductive technologies. Sperm banks- choosing certain donor genes within the population can increase/decrease and eliminate genes and another important alleles may be lost. Cloning Gene cloning- occurs at a cellular level, involves producing identical copies of one gene. Scientists select a gene, remove it from the source DNA and insert it into the DNA of another organism to make identical copies of that gene. Done using restriction enzymes. Polymerase chain reaction (PCR) - in vitro DNA cloning, widely used in research with many applications. It amplifies particular DNA sequence and make multiple copies. Whole-organism cloning (aka reproductive cloning)- involves creating a genetically identical organism, using somatic cell/s from another mature organism. It is a form of asexual reproduction and so it is considered a reproductive technology. Extremely costly process.

Somatic cell nuclear transfer - involves three animals. 1. One that donates the nucleus 2. One that acts as an egg donor 3. One that plays the role of surrogate mother Rate of success is still quite low → expensive technology The nucleus of a somatic cell is transferred into the cytoplasm of an egg with its nucleus removed, where the somatic cell is reprogrammed by the cytoplasmic factors to become the nucleus of a zygote. Dolly the sheep was created using SCNT. Embryo twinning- inexpensive technique. A short time after fertilisation, the embryo is split into two before the cells become specialised; this is done in the lab and the split embryos are then implanted into a surrogate for development (embryos are genetically identical). Horticulture- p lant propagation involves using a cutting of an existing plant and growing it to form a new plant that is genetically identical. The technique conserves variety and is faster than growing another plant from seed. Tissue culture involves growing small portions of plant tissue until they are ready to be transplanted. Has allowed for great discoveries about plant cellular structures and functions. Used to produce vaccines. E.g. Callus culture- a callus (unspecialised, unorganised mass of cells that divide) is produced after culturing cells (e.g. culturing tumour tissue). The culture is sustained on a gel medium and grown until they can reach the point of organ differentiation.

Advantages and disadvantages of cloning: http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway_pre_2011/living/cloningrev2.shtml

Recombinant DNA technology: Transgenic Organisms Transgenic species are those that have been created by moving a gene ‘across’ species- taking a gene from one species and inserting it into the DNA of another

species, and the addition of this gene to the germline means it can be inherited. Agricultural uses of transgenic organisms - Can be used to increase yield from livestock, while also improving nutritional value - The production of lower fat, more nutritious animal products produced by transgenesis could enable improvements in public health. - Can be used to increase the efficiency of metabolic processes e.g. improving phosphorus utilisation by pigs to reduce phosphorus waste. This means less land and water resources are used, thus beneficial to sustainability as well. - For greater quality of yield, e.g.: using transgenic for greater quantity, nutritional value and greater levels or nutraceutical protein; using the technology for overexpression of beneficial proteins Medical uses of transgenic organisms - Can expand understanding of genes in development of diseases, while allowing for testing for treatments - Transgenic animals can be used to study how genes regulate specific body functions - Transgenic mice are often used to study a range of diseases since their tissues and organs are similar to humans. E.g. ‘knockout mice’, a lab mouse from whom an existing gene is replaced or disrupted with an artificial piece of DNA. this results in a phenotype change (behaviour, physiological processes, appearance etc), thus allowing for a greater understanding of how specific genes contribute to/cause disease. - Production of recombinant DNA is helpful in vaccine research for vaccine development and they are cheap to produce, while also having fewer side effects.

Benefits of Genetic Technologies Agricultural benefits - Allows for production of crop and animal varieties better suited to specific environments. - Plants can also be made pest resistant (e.g. Bt cotton). - The use of transgenic organisms provides an opportunity to increase the productivity of marginalised land and reduce post-harvest losses. - Genetically modified plants also enhance nutrient levels while also allowing for greater survivability. E.g golden rice, genetically modified with vitamin A to improve eyesight, especially in developing countries. Increasing lipid content of starch-rich plants can also improve the nutritional value, assist in animal feed production, and oil and fuel production. - Also allows for genetically modified animals to be used as food sources. Medical benefits

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Genomics has the potential to influence medical care by allowing individualised treatments. - Recombinant DNA is also useful, e.g. artificially produced insulin to diabetes patients. - Monoclonal antibodies artificially clone antibody-producing cells to target specific antigens, used in cancer treatment. Industrial benefits - Genetically modified plants can be used to reproduce eco-friendly chemicals to replace non-renewable products. e.g.CSIRO’s work on potato plant modification to produce starch and make products. - Recombinant DNA techniques have been used to manufacture enzymes used in the food industry.

Effects of Biotechnology on Biodiversity -

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Modern biotechnology gives humans the potential to alter the path of evolution by artificially combining qualities of organism and creating transgenic species. This can increase biodiversity in the short term → new gene combinations in populations and new genes in individuals. But, in the long term, biodiversity will be reduced if organisms with desirable characteristics are reproduced and bred, using cloning and selective breeding. Another concern is wild varieties of plants/animals cross-breeding with genetically engineered ones, which can affect biodiversity. Major disadvantage of biotechnologies is the potential to reduce genetic diversity in the long term and increase the risk of populations being wiped out in response to disease/environmental change. E.g. genetically modified soybeans that make them resistant glyphosate, thus allowing for greater manufacturing of goods and economic benefits. However, this means that glyphosate can be used freely, which is potentially harmful to sensitive organisms rainforest ecosystems, especially since large rainforest areas have been cleared for GM soybean plantations, and high levels have of pesticide have been found in soybeans.

Effect of Biotechnology on agriculture -

Biotechnologies can increase or decrease the genetic diversity of species depending on their use. In the short term, introduced genes expand the population’s gene pool in the long term, genetic diversity can decrease since there is a possibility that desirable genes will replace other genes.

Social, economic and cultural influences on Biotechnologies Social context

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DNA fingerprinting techniques used in forensic science and paternity testing. Short tandem repeat analysis is used - a type of sequence marker, where repeats in alleles are counted to determine shared alleles between samples. This allows for highly accurate sample matching and problem solving capabilities, but is time consuming and costly. - There is also potential for discrimination from biotechnologies; a general debate around the issue including cloning. E.g. privacy issues about obtaining genetic information Economic context - Patenting GM products potentially gives multinational corporations a monopoly, while domestic farmers may be unable to acquire such seed for their crops, exacerbating income inequality and wealth distribution between developing and developed nations - High costs of research and development to bring GM foods to consumers. Cultural context - Cloning- religious argument that humans are ‘playing God’. also concern for animal welfare, and the argument of equality (access for everyone). Unforeseen health risks and safety concerns. Moral and legal concerns about cloning humans. - Different cultures have different approaches to the issue- need for universal issue

Future directions -

Future aims to improve treatment of a variety of genetic diseases e.g. CRISPR to identify and treatment of cancers, Alzheimer’s and schizophrenia. Agricultural advances and green chemistry will be used to improve efficiency and yield Organ transplants, synthetic cell manufacturing, and genetic engineering are also being advanced. Future struggles are human testing and suitable legislation....