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52 Cards in this Set
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Evolution defintion? |
The process of change that occurs in living organisms over many generations as a result of the environment's natural selection of favourable variations. Hence it pressures on species to evolve in order to develop favourable characteristics that help them to survive and reproduce. |
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Impact on the evolution of plants and animals of changes in physical, chemical and competition |
Physical: e.g. temperature and availability of water. Plant: australias plants have evolved water-saving mechanisms to adapt to increasingly dry climated arising as a consequence of continental drift. Animal: peppered months in england. Unpolluted areas, pale moths are camoflagued on pale tree-trunks to hide from predators, whilst dark moths are more visable. Chemical: e.g. water salinity and soil salinity. Plant: salt tolerant plants have evolved to inhabit areas with high salinity. Animal: mosquitoes. DDT was intially used to kill tben but they graduall gained a natural resistance and survived to pass on these characteristics. Competition: e.g. reproductive, food and water. Plants: potted in the same pot may compete for water and the weaker one may die. Animal: cant toads: they were introduced, and bread rapidly as they have no major predators. Thus, are a selective agent in the envrionment by placing competitive pressure for food, shelter, and breeding sites on native species. |
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Theories of evolution: - paleontology and transitional forms - biogeography - comparative embryology |
Paleontology: study of fossils. Supports evolution by providing evidence that organisms have changed over time. Transitional forms: examples of organisms that indicate the development of one group of organisms from another/from a common ancestor. E.g. fossil record such as jawless fish bony fish amphibians reptiles birds mammals. Biogeography: study of distribution of living things. -supports evolution by providing evidence on divergent evolution. E.g. rattites are found all over the southern hemisphere, and include animals like emus, Kiwis, cassowaries. Comparative embryology: the study of the similarities/differences in the embryos of organisms. Supports evolution by providing evidence of common ancestry, as embryos of different species can be very similar e.g. human embryos possess gill pouches despite not being aquatic. |
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Theories of evolution: - comparative anatomy - biochemistry |
Conparative anatomy: study of the similarities/differences in the structure of organisms. - supported by evidence of common ancestry. E.g. most land vertebrates have pentadactyl limbs. Biochemistry: branch of science concerned with chemical processes in organisms. - uses chemical processes to provide evidence of similarities in DNA, indicating evolutionary relationships. E.g. comparstive DNA sequencing. You compare similar gene sequences, scientists can measure the extent of variation between and within populations. |
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Darwin and wallaces theory of evolutions: account for divergent and convergent evolution |
Darwin and wallaces theory: in any population there are variations within individuals and in any generation there are offspring that do not reach maturity and reproduce. Their characteristics are removed from the population. So the organisms that survive and reproduce are well adapted and have favourable variations. Convergent evolution: when species living in similar environments develop similar adaptations despite not sharing a recent common ancestor. E.g. sharks and dolphins share a similar envrionment as they both live on open sea. Divergent evolution: when groups of a single species are geographically separared into isolated populations in different environments, and devlop different adaptations as a result. E.g. darwin found 14 different species of finches on the galapagod and cocos islands. They all had grey/black feathers, similar calls, Nests, eggs and courtship displays (indicating a common ancestor). But, their habitats, diets, body sozes and beaks were all dofferent (indicating divergence) |
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DNA hybridization and hos advanced have changed scientific thinking about evolutionary relationships |
DNA hybridization: used to identify similarities in DNA between organisms, and thus establish evolutionary pathways. DNA hybridization on primates shows that humans are more closely related to chimpanzees than to gorilla. Step: 1. Heat unwinds and separates the strands that make up the doubke helix. 2. Segments of DNA from two different species are cooled together. 3. On cooling, hydrogen bonds reform between complementary base pairs. 4. The degree of bonding reflecrs the degree of genetic similarity between species. 5. The degree of bonding is determines by fhe temperature necessary to separate the mixed strands again. |
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Comapre structure of a range of vertebrate forelimbs |
Crocodile: short, 5 digits (pentadactyl) and angle appropriate for water and land. Human: long, 5 digits (pentadactyl), and many functions including balance. Bat: thin, 5 digits (pentadactyl), bones suggest that they fold when resting, and help with light. Whale: dense and long, 5 digits (pentadactyl) and whole limb moves as one swimming. Frog: long and thin, 5 digits (pentadactyl), and help with balance by pushing off ground. |
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Historical developments in the theory if evolution |
1. Lamarck: inheritance of aquired characteristics. That individuals would lose/gain characteristic depending on need. Evidence: noticed variation within populations e.g. giraffes with long necks) and believed that when giraffes had to stretch their necks to reach food, they passed this trait of long-neckedness on to their offspring. Sociopolitical influences: mocked by contemporaries. Seen as threatening creationist views propogated by the church, causing religious controversy. Darwin and wallaces theory: theory of evolution. Evidence: finches on galapagos islands. Sociopolitical influences: opposition by religious groups. - darwins theory caused great furore in the society at the time. Great debates were fought out by evolutionists and creationists. - darwin was also blamed for many catastrophes in history, as people continued to wrongly apply the "survival of the fittest" to normal life. - darwin has been blamed for the destruction of religion and the rise of atheism, fascism, communism and even the second world war, as people like Karl Marx base their philosophies on the orgin of species. Mendel: law of independent assortment and random segregation: Inheritance of a trait determined by 'factors' passed on to offspring unchanged. - individual inherits one factor from each parent for each trait. - recessive traits may be passed on in genotype. Evidence: segregation: ratios of F1 and F2 provided evidence that the genes paired into homozygous dominant, homozygous recessive, and heterozygous groups. - combinations of genes present in neither parent promote idea that oairs of allels are passed on independently. Sociopolitical: not thought vaild because he was a monk. |
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Difference b/w allelle and gene |
Gene: a section of DNA that codes for a particular characteristic. Transferred from one parent to another (e.g. gene for eye colour). Allele: alternative forms of a gene. They occur in pairs and vary in effect, depending on the pairing. (E.g. the allele for blue eyes) |
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Distinguish b/w homozygous and heterozygous |
Homozygous: identical genes in their gene pairs (a.k.a 'pure breeding) Heterozygous: two different alleles making up their gene pair. The allele that is expressed is known the 'dominant one' |
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Relationship b/w dominant and recessive alleles and phenotype, using examples |
Genotyoe: the allels present on an organisms chromosome, for particular trait. Phenotype: the outward appearance of an organism, based on the dominant genotype. - a tall plant definitely has a phenotype of 'tall'. - its genotype is less certain, however. It could be homozygous, with two alleles telling it to be tall (TT) or heterozygous, with just one fene (the 'dominant' one) telling it to be tall (Tt). |
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Describe outcomes of a monhybrid crosses involving simple dominance using mendel's explanations |
Monohybrid cross: a breeding experiment looking at tge inheritance of only one characteristic. - a cross involving a homozygous tall plant (TT) and a homozygous short plant (tt) would produce offspring that are all tall, and with the genotype (Tt). |
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Genetic definition and Experiments carried out by gregor mendal |
Genetics: the study if heredity and variation. - mendel was known as the 'founder of genetics', carried out the first studies of inheritance using the garden pea. -he worked with true-breeding (homozygous) plants that produced all offspring identical to the parents, and concluded that there must be factors that are dominant and recessive. - when two true-breeding plants were cross-bred, only the dominay factor appeared in their offspring the F1 generation. - when the F1 generation was cross-bred, the recessive factor appeared in their offspring 1/4 of the time. |
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Describe the aspects of the experimental techniques used by mendel that lead to his success |
Controlling variables: avoided croo-breeding by removing stamens and pollinating by hand. - studied only one characteristic at a time - one independent variable. Reliabiltiy: repeated experiments many times. - used a large number of plants. - bred each variety for 2 years to ensure that the "character" was consistent. Accuracy: kept careful rwcord and counted the results he obtained. Logic: used peas (cheap, easily grown, produced new generations rapidly) - selected easily observable characteristics |
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Why mendel's work wasn't recognised |
Mendel published his results in a little journal in 1866, where it attracted little attention. Few reasons for this: - mendel was unknown as a scientist and thus had nobody to support or promotoe his findings. - at the time he published little was known about the cell. Indeed, darwins, whose theory already had been published, could not account for the variations he observed. - it was not until 1900, when more was known about the cell and chromosomes, and three scientists independently produced similar data, that mendel's work was recognised. |
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Describe an example of hybridisation within a species, and explain the purpose of this hybridization |
Hybridisation: the scientific production of an individual from two genetically unlike parents. Hybrid vigour: combining the best features of each parent to produce an offspring with a better chance of survival. - hybrids occur in nature and assist in increasing genetic variety. - created artificially by ensuring that the sex cells fertelized are from two different organisms. - e.g. csiro mandarins - merbeingold 2350: - parental organisms: imperial mandarin and ellendale tangor. - adv: produces sweet, juicy and easy-to-peel fruits that are seedless, are attractice to customers, and well-suited for export. - dis: expensive, take a long time to perfect, and hybrids cannot reproduce. |
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Rolde of sutton and boveri in identifying the importance of chromosomes |
Boveri: worked on sea urchins. Concluded: chromosomes are not all the same. All chromosomes are required for normal development. Sutton: worked on grasshoppers. Concluded: chromosomes carry heredity information. If two characteristics are on the same chromosome (linked genes), they will be inherited together. |
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Chemical nature of chromosomes and genes: |
Chromosomes: long strands of heredity information containing genes. 40% DNA and 60% protein. Genes: composed of DNA - ' deoxyribonucleic acid' made of repeating units called 'nucleotides', phosphate and sugar. |
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Identify that DNA is a double-stranded molecule twisted into a helix |
- A binds to t and c binds to g. - sugar is what directly binds the directlt to the bases not phosphate. |
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Define meiosis, crossing over, random segregation and independent assortmemt |
Meiosis: when a cell divides twice to produce 4 offspring, each with half the amount of genetic information of the parent cell. Crossing over: the swapping of genetic material between homologous chromosomes during metaphase. Random segregation: when chromosomes seperate during meiosis, it is random which gamete they end up in. This produces many gene combinations, which are different from the parents. Independent assortment: when alleles are randomly segregated, they are distributed independently of other alleles of other genes. I.e. (if you inherit gene X, you will not necessarily inherit gene Y, unless their linked.) |
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Relationship between the structure and behaviour of chromosomes durin meiosis and the inheritance of genes |
Behaviour of chromosomes: - parent cell undergoes two meiotic divisions to generste four haploid cells. These 'daughter cells' are genetic combinations of the parental genes. - this combination arises from crossing over, random segregation and independent assortment. What it means for inheritance of genes: - when chromosomes replicate during meosis, so do genes. Because chromosomes are made of DNA, and genes are coded with DNA. - when chromosomes are 'crossed over', so too are the genes that are on them. Thus, the behaviour of chromosomes have a direct influence on the inheritance of genes. |
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Role of gamete formation and sexual reproduction in the variability of offspring |
The events that create variation in sexual reproduction are: - random segregation: during meiosis, genes on different chromosomes sort independently. They can line up in the middle of the cell in many different ways. This produces many gene combinations, which are different from the parents. Crossing over: crossing over of genetic material during meiosis results in the exchange of genes b/w chromosome pairs. The combinations of alleles of the gametes will vary across cells and differ from the parent. Random fertilisation: when the male and female mate, the two different gametes randomly fuse. Many different combinations are possinle, and this causes variation. |
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Work that morgan did that led to the identification of sex linkage |
- morgan cross-bred red-eyed and white-eyed fruit flies (dorsophila), and when he looked at the unexpected ratios of eye colours that resulted in offspring, he realised that they weren't just simple mendelian crosses, and found that: * cross-breeding homozygous white-eyed males with homozygous red-eyed females lead to all their offspring being red-eyed. This is expected, and means the red-eyed trait is dominant. - but then crossing these red-eyed offsprinf resulted in a non-mendeliam ratio of results. Where normally we'd expect 75% to have red-eyes and 25% to have white eyes, 50% of offspring had white eyes, and - significantly - these were all males. Hence: - males have white eyes if they inherit just one recessive allele for white eyes. In order to inherit white eyes, they need to have two recessive alleles for white eyes. Conclusion: - males have only 1 X chromosome, so if they have the gene for an X-linked characteristic they always express it - they cannot be 'carriers'. - females have 2 X chromosomes, so they may not express an X-linked characteristic if they have just one copy - they can be 'carriers' - genes can also by Y-linked, but this is much rarer. |
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Describe inheritance of sex-linked genes that do no produce simple mendelian ratios |
Sex-linked: ex. Red-green colour blindnessm - as the gene is carried on the X chromosome, males only need one allele for colourblindness to exhibit the characteristic: * results in many more males being affected than females. * hence, simple mendelian ratios do not apply here. * for example, let H = allele for normal sight and h = allele for colourblindness. |
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Relationship b/w homozygous and heterozygous geneotypes and the resulting ohenotypes in examples of co-dominance |
Co-dominance: when both alleles are expressed in the phenotype. - normally traits are either dominant or recessive. In co-dominance, there is no recessive characteristic, as both characteristics are displayed and distributed phenotypically and genotypically. They are equals (e.g. in roan cattle): - red = RR - White = WW - Roan = RW * RR x WW = 100% RW - red cattle crossed with white cattle produces offspring that are all roan. * RW x RW = 25% RR, 50% RW, 25% WW |
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Outline ways in which the environment may affect the expression of a gene in an individual |
The envrionment can determine whether an individuals genotype is expressed as a phenotype. E.g. hydrangeas, due to ions in soil, are blue in pH<5, pink pH>7 |
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Process of DNA replication, and expain its significance |
- the significance of the ability of DNA to replicate itself exactly is that identical copies of genes can be made. - DNA replication is made possible because the molecule is a double helix, and because the nitrogenous bases only pair complementarily. The steps for DNA replication: - the parent DNA molecuke unwinds into 2 separate strands, at one end. - and the two strands become exposed, free nucleotides floatin in the nucleoplasm attach to the exposed bases, A with T and C with G. This ensures that the replication is exact. - the joining of nucleotides together is catalysed by DNA polymerse. Significance: genetic information is passed on from generation to generation (e.g. sexual reproduction, where the genetic code is replicated and half of this information passes into each gamete. Fertilisation gives gives the new organism half the genetic material from each parent). The DNA contains the gentic information required to make an entire organism. When a cell divides, it replicates exact copy of this genetic code. |
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Outline, using a simple model, the process by which DNA controls the production of polypeptides |
- Genetic information is organised into genes - certain sequences of bases. Each gene contains the coded information to make polypeptides for the cell. - DNA does not make proteins for the cell directly, but provides the information for the cell to synthesise polypeptides. It does this by transcription and translation. Transcription: information coded in DNA is copied into a strand of RNA. - DNA strand unwinds. - RNA polymerse links complementary RNA nucleotides to the unwound DNA - forming an mRNA stand. The 'start' codon (AUG) and the 'stop' codon (UAA/UAG/UGA) control the length of this strand. - mRNA strand is modified so that it contains only exons - regions that code for proteinsm - mRNA moves from the nucleus of the cell into the cytoplasm. Translation: information on RNA is used to make a polypeptide chain: - mRNA strand binds to a ribosome. - tRNA carrying anticodons binds to mRNA codons. - a Polypeptide chain is formed until the 'stop' codon is reached. - the newly-formed polypeptide chain is released into the cytoplasm. |
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Explain the relarionship b/w proteins and polypeptides |
- a Polypeptide is made up of a chain of many amino acids. - a protein is made up of polypeptides. |
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Beadle and Tatum's 'one gene-one protein' hypothesis and explain why this was altered to the 'one gene-one polypeptide' hypothesis |
One gene-one protein: that each gene is responsible for the building of a single, specific protein. Experiment: - in 1941, beadle and tatum used neurospora crassa (bread mould) to show a connection b/w genes and proteins by mutating the genes of neurospora crassa in such a way that there were unable to carry out specific enzymatic reactions. Hypothesis: a one-to-one relationship b/w genes and specific enzymes would make it possible to create mutants that are unable to carry out specific enzymatic reactions. Experimentation: exposed neurospora crassa to X-rays and UV radiation to study the resulting mutations. Results: each strain lacked the ability to produce one essential nutrient - caused by the absence of the necessary enzyme. Conclusion: by growing different strains, they were able to establish which enzyme was lacking in each strain. As a result, thy found that the genetic mutation was at a specific site on the chromosome, and each was associated with a different enzyme. - they worked neurospora crassa because: * easy to grow and maintain * easy and not unethical to indice mutation. * easy to identify and isolate mutants. - changed to one gene-one polypeptide as: * beadle and tatum presumed that every gene leads to the direct formation of a single protein, but we know from our knowledge of polypeptide synthesis that this is not the case - proteins are formed, but only indirectly. First, polypeptides must be formed by transcription and translation. - in calling it the one gene-one protein hypothesis, beadle and tatum were skipping this vital step, hence it was later changed |
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Develop a simple model for polypeptide synthesis |
Making proteins is kind of like writing a book: - letters are like bases - words are like codons - sentances are like polypeptide chains - chapters are like proteins (eg. Haemoglobin). - organisms are made of a whole lot of chapters, like a book. |
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Show that changes in DNA sequences can result in changes in cell activity |
A base being changed or shifter by processes such as deletion, substitution or insertion of a nucleotide results in the formation of a different amino acid codon that can form a dusfunctional enzyme that can disturb cell activity. |
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Explaim how mutation in DNA may lead to the generation of new alleles |
Mutation: changes in the DNA information on a chromosome. - any change, therefore, results in changes to the polypeptides that are produced, and a source of new alleles. * if mutation occurs in somatic cells (just your regular body cells), it won't be passed on. * if a mutation occurs in the gametes (sex cells), it will be passes on to offspring. * the word 'mutation' has a negative connotation, but most mutations are actually neutral - not affecting the phenotype at all. - mutations can accumulate, however. For example, several oncogenes, combined with the mutation of tumour suppressor genes can result in cancer A change in DNA sequence: - most mutstions are a change in DNA sequence. -the smallest type is point mutation, where only one base changes. - large changes can alter the shape of the chromosome: * Deletion: some of the DNA is lost from a chromosome. * Duplication: A section of the chromosome is copied on the same chromosome; that is, the same section of DNA appears twicem * Inversion: a section breaks off and is reattached the wrong way. * translocstion: a piece of DNA from one chromosome breaks off and attaches to a neighbouring chromosome. * amplification: a section of DNA os repeated many times; it is a form of duplication, except many more copies. - as changes in the DNA or chromosomes creates new proteins, this can in turn create new alleles of genes. - this increases variation. |
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Discuss evidence for tbe mutagenic nature of radiation |
Mutagen: an environmental factor that causes mutation in genes. E.g. radiation from atomic bonds and UV rays. - examples of radiation causing mutation are the evidence for this include:* * beadle and tatum used radiation to produce mutation in neurospora crassa. * human exposed to high dose of UV show increased incidence of skin cancer. *hiroshima bomb in 1945 caused many to die of lukaemia. |
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Explain how an understanding of the source of variation in organisms has provided support for darwins theory of evolution by natural selection |
- darwins theory of evolution if based on the idea that variation occurs amongest individual members of a species. - our knowledge and understanding of genetics tells us where this variation comes from: * random segregation during meiosis * crossing over during meios * random mutation of DNA - these variations that are the agents that selection acts upon (i.e. the variations deemed 'beneficial' will eventually become more prevalent as the individuals with them are avle to survive). |
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Describe the concept of punctuater equilibrium in evolution, and hoe it differs from the gradual process proposed by darwin |
Punctuated equilibrium: is the theiry where instead of gradual transitions over millions of years there have been periods of rapid evolutionary change followed by long periods of stability. E.g. new dinasours in the judith river area: -unchanged for 5 million years, then new species seemed to 'suddenly' appear 500,000 years later. - research revealed that sea levels rose and drowned the area. The dinasours living there had moved out and evolved to suit their new environments. Transitional have been found around the area. |
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Watson and crick collaboration in determining structure of DNA and the impact of the quality |
Work: they came up with a vague and unsupported model of DNA, but without adequate evidence they could not be sure. How ever after seeing franklin's findings, they knew their model was correct, and produced a 3D model of DNA structure, as well as a theory about the double helix - publishing their findings and recieving credit. Collaboration: they worked well as a team and used findings of other scientists in their research. E.g. they used edward chargraff's work on nitrogen bases to suggest that nitrogen bases were complimentary, and the "rungs of the ladder" of DNA. Impact: they collaborated very effectively, and were able to use each other's expertise to form scientific conclusions easier and more accurately. Impact on scientific community: Watson and crick are the main scientists credited with the discovery of the structure of DNA winning a nobel prize along with wilkins in 1962 |
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Franklim and wilkins importance in determining the structure of DNA and the impact of the quality of collaboration and communication |
Work: franklin used X-ray crystallography to find the X-ray diffraction pattern from crystalline DNA- showing DNA's double-helix shape. She did not announce her findings, though because had inadequate evidence of their significance. Wilking showed watson franklin's work (without her permission) filling in the missing pieces of the puzzle for him. Collaboration: they didn't get along. They disliked each other and did not work collaboratively. Impact of collaboration: they did not collaborate effectively, and thus were unaware of the work each-other were doing. Because of wilkins' actiobs, franklin was never properly acknowledged for her contribution. Impact of collaboration on scientific community: wilkins received a nobel prize in 1962 despite having far less influence than franklin on the discovery. Franklin died at 37, and nobel prizes aren't awarded post-mortem, yet still, her very significant contribution has never been formally acknowledged. |
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Reproductive techniques: - artificial insemination - artificial pollination - cloning |
Artificial insemination: the injection of male semen into the vagina of a female without sexual intercourse. Artificial pollination: when humans take the pollen from one plant with desired features and place it on the stigma of another flower. Cloning: producing an organism with the identical genetic make-up of the parent cell. - these are all examples of artificial selection. - whilst this produces offspring that have more favourable characteristics, it also reduces genetic variability within populations over time by creatinf a 'monoculture' that is vulnerable of the environment changes. E.g. the irish potato famine was caused by a single fungus that was able to infect all potatoes, as they were all identical |
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Discuss the potential impact of the use of reproduction technologies on genetic diversity of species |
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Describe a methodology used in cloning organisms |
animals such as dolly (1997) have been cloned by nuclear transfer: - extract desired DNA from adult species. - implant DNA into a denucleated egg from another adult. - implanting embryo unto a surrogate female where it grows and divides, and is born like normal. - the offspring will be a genetic match with fhe donor DNA, not with the surrogate. |
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Processes used to produce transfenic species and include examples of this process and reasons fo its use |
Transgenic species: an organism containing inserted genetic material not normally present. Used to give organisms favourable characteristics for human use. - steps to produce transgenic species: 1. Useful gene is identifed. 2. Gene is 'isolated' from its DNA strand using restrictions enzymes that break the hydrogen bonds in the triplet; causing 'sticky ends'. 3. The sticky ends are annealed (connected) with the enzyme DNA ligase. 4. The new gene is inserted into the cell of an organism, sometimes using a vector. 5. The egg is allowed to develop - producing offspring that are transgenic. E.g BT crops: is a bacterium that naturally produces chemicals that kill specific insects. Genetically modified crops have genes of BT pesticide inserted - meaning they produce their own BT and no longer need to be sprayed with pesticides. Cold strawberries: a gene from salmon that allows it to survive in cold temperatures is inserted. The strawberries can survive and grow in cold temperatures as a result. |
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Transgenic species and debate the ethical issues arising from their development and use |
- implanting the bGH (bovine growth hormone) in salmon: * produces larger, faster growing fish (= more food + cheaper). * however, if these fish were to be released in the wild, they could disrupt natural ecosystems. - implanting the gene for lectin in potato plants: * Protects against insect attack (less vulnerable plants = safer food source). * however, 'escape' of transgenic potatoes into the wild could disrupt natural ecosysyems. - ethical issues: Postivies: - can create treatment for himan condition (e.g. diabetes using transgenic bacteria) - can create foods with higher nutritional value. - more crops (and therefore cheaper; useful in areas where there is starvation). Negatives: - release into the environment they could disrupt the food web. Due to their increased ability to survive. - reduces biodiversity - unkown health consequences |
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Define the terms health and disease (search for better health) |
Health: the state of physical, mental and social wellbeing - not just the absence of disease. Disease: the state of 'impaired' functioning; physical, mental or social. - difficult to define because there are many components, and they are all subjective. They can also vary b/w within individuals, depending on: * an individuals normal level of functioning. * what they expect their quality of life to be. - to demonstrate their subjectivity, consider that someone who has loved their whole life in a wheelchair mau still consider themselves to be healthy if they feel 'weel', whilst someone who is physically fit may believe themselves to be unhealthy if they have a cold. |
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Links b/w gene expression and maintenance and repair of body tissue (search for better health) |
Gene expression: the process by which inheritable information from a gene is made functional being 'switched on' and manipulated into a functional protein. - if mutation occurs, gene expression alters and the maintainence and repair of tissues is disrupted as protein synthesis, mitosis and the cell-cycle is also affected. (E.g. when you cut yourself, the gentic code in your cells is responsible for stimulating mitosis - forming new tissue to repair the damage done). Another example of this is when the mutation of the BRCA1 tissue to repair the damage done). Another example of this is when the mutation of the BRCA1 gene inhibits its normal function of tumour suppression, increasing the risk of breast cancer. |
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Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintainence of health (search for better health) |
All these processes occurr as a result of the proper functioning of genes. If the processes are impaired, then the organisms biological health may be impaired. Function of genes: heredity units passed from parent to offspring: *ensures the correct proteins are produced: in order to enable cellular processes. * proteins and polypeptides synthesis need to be controlled so that the correct proteins are produced at the right time, and in the right amounts. This is called gene expression. * gene expression is essential to maintain goo health, As if genes are faulty and the proteins/polypeptides they make are also faulty, then cell processes/structures may be abmormal, leading to disease. Mitosis: cell division that produces cells identical to the parent cell: * cells are important for repair, replacement and growth. * without mitosis, an organism cannot carry out these functions. Cell differentiation: when a cell changed from an unspecialised one to a specialised on: * differentiation if when a cell has many of its genes permanently 'switched off' and only uses some of them to perform specific functions; ex. Liver cells are called 'hepatocytes'. * undifferentiated cells can form tumors. Cell specialisation: when cells have differentiated to perform a specific function: * specialised cells have lost other functions (e.g. nerve cells only transmit and conduct messages). * specialised tissues work together in a healthy organism in a controlled and coordinated way to perform specific functions. |
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Describe b/w infectious and non-infectious disease (search for better health) |
Infectious: caused by an organism that can be transferred (dorectly or indirectly) from one person to another. E.g. influenza, malaria, herpes, measles. Non-infectious: not caused by organisms. Ofteb genetic and can be related to lifestyle or envrionment e.g. hemophilia, cardiovascular disease, skin cancer). |
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Identify the conditions under which an organism is described as a pathogen (search for better health) |
An infectious organism that can produce a disease e.g. mycobacterium tuberculosis, or salmonella enteritidis. |
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Explain why cleanliness in food, watee and personal hygiene practices assist on the control of disease (search for better health) |
Many pathogens are microscopic, and can be present in food, in water, and on the body wiithout us even knowing it. - these pathogens can enter our bodies by various routes and cause disease. - minimising the number of organisms in food/water (ex. Boiking water, good food sanitation) minimises the chance of a pathogen entering our body when we eat and drink. - good personal hygiene (e.g. washinf hands, cleaning wounds) ensures that body opeinings are clean so that the number of microorganisms that might enter is reduced. |
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Describe ways in which drinking water can be treated and explain how these methods reduce risk of infection from pathogens (search for better health) |
- water from catchment areas run into creeks or streams, which kead to several main dams managed by sydney catchment authority. - water passes through filtrarion plants which may remove pathogens e.g. protozoa. * flocculants are added to bind mocrobes, dirt and other suspended matter together, making it easier to remove them by filtration. - water is treated with chlorine or monochloramine to kill most organisms that may still be present. Any remaining cryptosporidium soores are inactivated by these chemicals. - samoles of sydneys drinking water are tested throughout all stages of treatment for things like coliform bacteria, colour and turbidity. |
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Describe the contribution of Pasteur and koch to our understanding of infectious diseases (search for better health) |
Pasteur: performed experiments the disproved theory of spontaneous generation by showing that micro-organisms come from pre-existinf micoorganisms. * determined cause of rabies, chicken pox, anthrax and cholera. * worked out the basics of fermentation. * his scientific method led to the development of new scientific branches like immunology. Koch: grew bacterial colonies on agar plates. - koch's postulates: linked specific micro-organisms with specific diseases. * the organism believed to cause the disease must always be present when the disease occurs. * isolate organism from the host with this pure microorganism. Does the host develop the same symptoms as the original sample. * isolate and re-grow the microorganism from step 3 - compare it to the microorganism from step 1. Is it identical? |
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Distinguish b/w types of pathogens and name one example of a disease caused by each (search for better health) |
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