Blueprint of life Miss Heretakis Start: 27/3 Past HSC questions : https://sciencegreystanes.wikispaces.com/HSC+Biology Miss Heretakis

Applications and implications of genetics 5. Current reproductive technologies and genetic engineering have the potential to alter the path of evolution The term reproductive technology applies to any use of technology to assist and improve reproduction. At first, humans obtained food by hunting and gathering; they then began raising their own animals and growing their own crops and soon realised the advantage of selecting seeds from the best crops and breeding the best quality animals, to improve the quality and yield of future generations. This was the start of selective breeding or artificial selection. 27/3

Applications and implications of genetics As time went by, early agriculturalists discovered that cross-breeding different varieties of organisms resulted in stronger, healthier offspring than inbreeding— a phenomenon known as hybrid vigour. The trend to ‘manipulate’ the phenotype of offspring to achieve desirable characteristics has continued over many hundreds of years, becoming more sophisticated as technology has improved.

Investigating hybridisation and its genetic effects Completed in booklet 2 process information from secondary sources to describe an example of hybridisation within a species and explain the purpose of this hybridisation The term hybridisation means the cross-breeding of two genetically non-identical individuals. This may mean crossing parents of: Same species, who show genetic variation (intraspecific hybridisation) e.g. Labrador x poodle = labradoodle Different species (interspecific hybridisation) e.g. Horse x donkey = mule Interspecific hybrids are bred by mating individuals from two species, normally from within the same genus. The offspring display traits and characteristics of both parents, but are often sterile, preventing gene flow between the species. Sterility is often attributed to the different number of chromosomes between the two species. For example, donkeys have 62 chromosomes, horses have 64 chromosomes, and mules have 63 chromosomes. Mules, and other normally sterile interspecific hybrids cannot produce viable gametes, because differences in chromosome structure prevent appropriate pairing and segregation during meiosis, meiosis is disrupted, and viable sperm and eggs are not formed.

Investigating hybridisation and its genetic effects Completed in booklet 2 Successful hybridisation leads to hybrid vigour —increased strength, better health and greater fertility in the hybrid individuals than is usually found in the homozygous individuals from which they were bred. Hybrids often display advantages that are not present in either of the parental varieties, as a result of the compounded effects of their new gene combinations, giving new phenotypes on which natural selection can act.

Investigating hybridisation and its genetic effects Completed in booklet 2 Advantages of hybridisation Increases genetic variety. May combine best features of each parent, resulting in hybrid vigour. Disadvantages of hybridisation May combine weaker features of each parent, resulting in the offspring having less stamina, less resistance to disease or changes in the environment, lower crop yields, and so on. It is a costly procedure. Sometimes the hybrid offspring are infertile

Investigating hybridisation and its genetic effects Completed in booklet 2 Wheat hybridisation in Australia See previous notes on wheat hybridisation (or read page 217) and then complete the secondary source investigation.

Reproductive technologies and the gene pool identify how the following current reproductive techniques may alter the genetic composition of a population: artificial insemination; artificial pollination; cloning Current reproductive techniques include artificial insemination, artificial pollination and cloning. With these techniques, humans can artificially create variations in gene combinations and chromosomes and therefore alter how the offspring looks and performs and also the proportion of genes in the population.

Reproductive technologies and the gene pool Selective breeding techniques are reproductive technologies that may be used to achieve hybridisation. Selective breeding can be thought of as a form of artificial selection imposed by humans, when they conduct deliberate crosses of living organisms to obtain a combination of desirable characteristics in the offspring.

Reproductive technologies and the gene pool Selective breeding in plants - Artificial pollination This requires fertilisation. Pollen from a selected breed of plant with desirable traits is artificially transferred to the female stigma. This creates new hybrid species and so alters the genetic composition of a population. This process gives the breeder a greater degree of control over the breeding process. Was used by Mendel in his experiments with pea plants and also by Farrer to create hybrid wheat. Artificial pollination is still used today.

Reproductive technologies and the gene pool Selective breeding in animals Selective breeding in animals, in its most basic form, involves mating a male that displays one desirable characteristic with a female with another desirable characteristic in the hope that some offspring will inherit both characteristics. E.g. crossing a male of the Friesian variety (produces large quantities of milk) with a Jersey cow (produces creamy milk) will create some offspring who produce large amounts of creamy milk. Offspring that reflect this desirable trait are then selected for further breeding. However, selective breeding also has its disadvantages. 27/3 Disadvantages: The breeding of undesirable side effects, for example, when Friesian cattle are crossed with Jersey cattle to produce cows that produce large quantities of creamy milk, some of these hybrid cows have such large udders that they can hardly walk Selective mating is time-consuming and costly. It involves the transport of large animals over long distances, risking putting them together with a breeding partner of the opposite sex, hoping they will not injure each other and then waiting for them to mate.

Reproductive technologies and the gene pool Selective breeding in animals - Artificial insemination This requires fertilisation but NOT mating. Sperm from a selected breed with desirable characteristics is removed from the male (using mechanical stimulation). This fluid is then chilled and transported to be artificially transferred to several selected females through the process of insemination. 29/3 Disadvantage: many offspring arise from one father, leading to reduced genetic variability. Advantages: Transporting frozen sperm overcomes the problem of transporting large animals over long distances, is cost effective and reduces the danger to animals of injury in transit or during mating. Many females can be inseminated and so one male can produce offspring with several females. Since the semen can be frozen indefinitely, a male can be dead but still produce offspring. It is being used in conservation, to increase the numbers of endangered species e.g. sharks

Reproductive technologies and the gene pool In vitro fertilisation (IVF) is an artificial reproductive technology where fertilisation occurs OUTSIDE the mother’s body. The zygotes are cultured until they have progressed to an early stage of development and they can then be transferred into the biological mother into a surrogate mother. IVF can be used for couples where one person (or both) is sterile. Genes that would have been lost in natural populations will be passed onto offspring and remain part of the population. Sperm banks are created, from which people can choose desired characteristics, thereby increasing the proportion of certain genes in a population. 29/3

Reproductive technologies and the gene pool Artificial pollination, insemination and IVF allow humans to manipulate combinations of alleles and increase the frequency of those seen as ‘favourable’ within a population. They do not allow humans to determine the exact combination of genes that will be passed on; favourable traits may be linked to unfavourable ones that may bring discomfort or suffering to, animals. There is a short-term increase in the genetic diversity when new hybrid species are created, but in the longer term the continued breeding of the same hybrid lines decreases genetic diversity. 29/3 Was used by Mendel in his experiments with pea plants and also by Farrer to create hybrid wheat. Artificial pollination is still used today.

Reproductive technologies and the gene pool Cloning – taking the ‘unknown’ out of selective breeding Reproductive cloning does not require fertilisation. Cloning involves making an individual genetically identical to the organism that already exists using single cells. Identical twins are natural ‘clones’ of each other Plant cuttings are commonly used to ‘clone’ plants 29/3 Botanists have been using plant cuttings, the splitting of bulbs and other forms of asexual reproduction to propagate plants over many centuries. Animals were first cloned a century ago when two-celled embryos of sea urchins and salamanders were split.

Reproductive technologies and the gene pool Types of cloning: Reproductive cloning: involves asexually creating a genetically identical, fully developed whole organism, using a cell (or a few cells) from another mature organism. Therapeutic cloning: involves using cells from an individual to produce a cloned early embryo, which is then used as a source of embryonic stem cells to replace degenerating adult tissues or to repair damage. Gene cloning: involves producing identical copies of DNA segments using recombinant DNA therapy. 29/3 Botanists have been using plant cuttings, the splitting of bulbs and other forms of asexual reproduction to propagate plants over many centuries. Animals were first cloned a century ago when two-celled embryos of sea urchins and salamanders were split. Therapeutic cloning - https://www.youtube.com/watch?v=eNnmpu4apK4 Gene cloning - https://www.youtube.com/watch?v=dRW9jIOdBcU

Reproductive technologies and the gene pool Embryo-splitting leading to multiple births occurs naturally and can be fairly easily replicated in a laboratory. Cloning from adult cells (of living or deceased organisms) is not a phenomenon that occurs in nature. In 1996, Dolly, a sheep, was the first mammal to be artificially cloned from an adult cell. 29/3 Botanists have been using plant cuttings, the splitting of bulbs and other forms of asexual reproduction to propagate plants over many centuries. Animals were first cloned a century ago when two-celled embryos of sea urchins and salamanders were split.

Reproductive technologies and the gene pool Cloning alters the genetic composition of a population Cloning is used as a form of selective breeding once an ideal hybrid has been obtained, e.g. when growing seedless grapes. The advantage is that cloning reduces the ‘unknown’ element in selective breeding. If many clones are produced from one parent, the effect would be to reduce the variability of the population. The disadvantage of cloning is that if all members of a species are identical, the population is less likely to survive sudden environmental changes and would be vulnerable to foreign pathogens. 29/3

Methodology of cloning Read pages 223-225 process information from secondary sources to describe a methodology used in cloning Somatic cell nuclear transfer (SCNT) The nucleus is removed from an unfertilised egg cell. The nucleus of a body cell is injected into the enucleated egg cell. 29/3 https://www.youtube.com/watch?v=-Qry1gYYDCA

Methodology of cloning Read pages 223-225 process information from secondary sources to describe a methodology used in cloning Somatic cell nuclear transfer (SCNT) The cell is cultured then implanted into a surrogate mother. When it is born, the organism is a clone to the sheep that donated the somatic cell. Continued… https://www.youtube.com/watch?v=-Qry1gYYDCA

Biotechnology, genetic engineering and transgenic species outline the process used to produce transgenic species and include examples of this process and reasons for its use Biotechnology is any technique that uses living organisms to make products. In ancient times, people were unaware that they were employing biotechnology, e.g. using yeast for the fermentation of wine In modern times, biotechnology has come to be associated with genetic modification (genetic engineering) of living organisms – i.e. manipulating the DNA of living organisms to artificially combine specific qualities of different organisms.

Biotechnology, genetic engineering and transgenic species Genetic engineering allows specific desirable genes to be moved from one species to another. Genes can be ‘cut and pasted’—removed from the cells of one organism and inserted into the genome of another organism, where they become part of the new organism’s genetic make-up and are passed on to its offspring.

Biotechnology, genetic engineering and transgenic species A transgenic organism is one whose normal genome has been altered by introducing a gene from another species (transgene) into it in such a way that the organism can pass on this transgene to its offspring during reproduction. /3/17

Biotechnology, genetic engineering and transgenic species See diagram on page 227 Process of producing transgenic species CUT: a gene for a favourable characteristic is removed from the cell of an organism using restriction enzymes COPY: multiple copies of the gene are made (gene cloning)—usually carried out in bacteria PASTE: the genes are inserted (injected) into an egg cell of another species and after fertilisation become part of the newly formed organism’s DNA The egg develops into a mature organism (a transgenic species) with the new gene ‘switched on’ to function. Genetically modify: add or remove genes To assess whether the gene has been incorporated: A gene for a fluorescent protein from jellyfish is now used to determine whether an individual has successfully incorporated a transgene. This gene is used as a marker and is attached to the desired gene that will be inserted into prospective transgenic organisms. The gene with attached marker is injected into an egg cell and the resulting offspring fluoresce under certain lighting conditions.

Biotechnology, genetic engineering and transgenic species Example: Transgenic cotton (Bt cotton plants) REASON FOR THE PRODUCTION OF BT COTTON Over the years, traditional pesticides used on cotton plants had to be made stronger and be applied more frequently to eradicate insect pests such as the caterpillar of the Helicoverpa zea moth, which destroy hundreds of millions of dollars worth of cotton each year. With increased sprayings, these pests were building up immunity to the pesticides due to natural selection.

Biotechnology, genetic engineering and transgenic species The insertion of the Bt gene into the cotton plant has reduced the need to use pesticides to kill the caterpillar, which is better for the environment and reduces the development of pesticide resistance in the caterpillars.

Biotechnology, genetic engineering and transgenic species See pages 228-229 for more detail PROCESS USED TO PRODUCE OF BT COTTON Normal cotton seedlings cut into small pieces and grown into embryo Bt gene is extracted from Bacillus thuringiensis bacteria using restriction enzymes Agrobacterium tumefaciens bacteria acts as a vector to insert Bt genes Cotton plant embryos are dipped in a solution of the vector Agrobacterium and extracted Bt genes – the vector bacteria injects the Bt genes into the cotton cells Embryos grown in tissue culture Resulting plants are now a transgenic species

Biotechnology, genetic engineering and transgenic species See pages 228-229 for more detail

Ethical issues arising from the use of transgenic species analyse information from secondary sources to identify examples of the use of transgenic species and use available evidence to debate the ethical issues arising from the development and use of transgenic species Read pages 230-232 6/3/17

Impacts of Impact f technologies on genetic diversity Read pages 232-235 discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered Questions and answers - https://wikis.engrade.com/a121biology2012/currenttechnology Notes: Reproductive technologies can have a positive and negative affect on the diversity of species. For example in Australia new varieties of tomatoes have been genetically altered to have a longer shelf life and a greater taste. This in a sense is a positive because if the tomatoes are a success in the market place they will continue to be genetically engineered while other tomatoes will be discarded. This in turn produces a larger yield of tomatoes for the farmer. The negatives for the production of these tomatoes are that they are all genetically similar. This in turn limits genetic variation within a population of the tomatoes. This also makes the crop susceptible to disease, which in turn could wipe out a whole crop. Tomatoes that are not genetically modified have a greater chance of spreading their desired characteristics from one generation to the next. An animal example that has been genetically modified is transgenic sheep. These sheep have had cysteine inserted into their egg, this egg develops into a sheep, which produces high quality wool and the cysteine gene is passed on from generation to generation. Once again a positive for the development of this species is that high quality wool is being produced for the market place. The negatives for this transgenic species are that there is a lack of genetic variation within the population causing a lack of diversity. This species maybe susceptible to disease causing a decrease in wool production and the loss of money.

Impacts of Impact f technologies on genetic diversity Read pages 232-235 discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered Modern biotechnology gives humans the potential to alter the path of evolution by artificially combining the qualities of organisms that once were separate species (e.g. creating transgenic species). This could increase biodiversity in the short term because it slows genes to be moved from one species to another to produce new gene combinations This could also decrease biodiversity in the long term if large numbers of identical organisms (clones) are produced and bred, or if organisms are selectively in-bred to maintain parent lines of hybrids that benefit us in terms of their agricultural produce. This can occur to the point where the original genes may be lost forever.