biology4alevel600

There are social implications related to using genetically modified organisms in food production. modified crop plants become agricultural weeds and invade crop habitats intoduced gene(s) may be transferred by pollen:              - to wild relatives --> more invasive hybrid offspring              - to unmodified plants on farms with organic certification modified plants can be toxic and produce allergies --> fatal to humans and animals that eat it herbicides will leave toxic residues on crops genetically modified seeds are as expensive as herbicides --> no advantage growers need to buy new seeds every season loss of traditional varieties 19.3 Genetically modified organisms in agriculture  The ability to manipulate genes has many potential benefits in agriculture, but the implications of releasing genetically modified organisms (GMOs) into the environment are subject to much public debate in some...

Genetic technology can provide benefits in, for example, agriculture and medicine, but has the associated risk of the escape of the gene concerned into organisms other than the intended host. Herbicide resistant crops Fields of crops are sprayed with herbicide to kill weeds that compete for space, light, water, and ions to increase crop yield . Oil seed rape a source of vegetable oil and biodiesel fuel modified oil seed rape is resistant to the herbicide glyphosphate (inhibits the synthesis of 3 amino acids: phenylamine, tyrosine, trytophan)              - glyphosphate is absorbed through leaves and is transported to growing tips the gene transferred into crop plants come from a strain of the bacterium Agrobacterium Tobacco resistant to herbicides: sulfonylurea and dinitroaniline genes taken from other plant species Effects on the environment: the GMed plants become agricultural weeds pollen will transfer the gene to wild relatives, producing hybrid...

Gene therapy: treatment of a genetic disorder by altering a person's genotype (insert functional alleles of genes into cells) Common vectors: virus : retrovirus, lentivirus, HIV, adeno-associated virus (AAV) liposomes - small spheres of phospholipids naked DNA - retrovirus: inserts genes randomly into host's genome. If the gene is inserted into another gene or regulatory sequence of a gene, it could activate a nearby gene and cause cancer - lentivirus: inserts genes randomly into host's genome, but this virus can be modified to inactivate replication e.g.: HIV - adeno-associated virus (AAV): does not insert genes into host genome --> gene is not passed to daughter cells when a cell divides --> the virus can be used successfully with long-lived cells Severe combined immunodeficiency (SCID)  a crippled immune system sufferers may die at infancy due to normal infections inability to make adenosine deaminase (ADA) --> T-lymphocytes of sufferers are removed and n...

Genetic engineering is improving the quality (nutrition) and yield of crop plants and livestock  --> therefore is solving the demand for food in the world 1. Golden Rice - genetically modified rice produces large quantities of β-carotene in endosperm --> human cells convert β-carotene to Vitamin A - Golden Rice has same yield, pest resistance and eating qualities as the original varieties - normally: deficiency of Vitamin A can lead to blindness and death (due to a weak immune system) Vitamin-A is fat soluble: found in oily-fish, dairy, liver,... Pro-vitamin A is present in the aleurone layer, not in the endosperm in rice -genes for carotene production is taken from:   and inserted into rice daffodils common soil bacterium Pantoea ananatis *ethical implications? Some organisations condemn Golden Rice: It is the wrong way to solve poverty . Solving political, cultural and economic issues will help lower poverty, as people will be given a more varied diet From question...

Genetic screening: analysis of a person's DNA to check for the presence of a particular allele * available for adults, fetus, embryo,... - BRCA1 and BRCA2 : faulty alleles that lead to breast and ovarian cancer in females and breast cancer in males ---> elective vasectomy - pre-implantation genetic diagnosis (PGD) : carry out the IVF procedure (sperm and egg in a dish) when it reaches the 8-cell stage, remove one cell and analyse the DNA for disease alleles               - disease allele absent: embryo chosen for implantation               - disease allele present: embryo is discarded ---> avoid pregnancies with haemophilia, sickle cell anaemia, Huntington's disease, cystic fibrosis,... provides information about the increased risks of people having genetic conditions people prepare for the late onset of genetic conditions like Huntington's disease identify whether embryos from IVF will develop genetic cond...

Bioinformatics is the  collecting , processing and analysis of biological information and data using computer software. Bioinformatics build databases which hold gene sequences and sequences of complete genomes . These sequences can be matched --> calculate degrees of similarity (close similarities indicate recent common ancestry) human genes may be found in other organisms and are used to model for investigating the way in which such genes have their effects e.g.: Plasmodium genome: used to find new methods to control parasites             ---> reading the gene sequences provides information to develope vaccines for malaria Advantages of using human proteins produced from recombinant DNA 1. Insulin  reliable supply available for increasing demand is not dependent on factors e.g.: meat trade acts faster than animal insulin or slower over a long period of time 2. Factor VIII - genetically modified hamster cells produce factor VIII F...

Genetic markers uses enzymes that produces fluorescent substances. There used to be antibiotic resistance gene markers, but there was the chance that they would spread the antibiotic resistance to other new strains of bacteria. Genetic markers Green fluorescent protein (GFP) from jellyfish: gene inserted into plasmid --> taken up by bacteria shine UV light --> identify genetically modified bacteria β-glucuronidase (GUS) from E.coli: transform into incubated with colourless/non-fluorescent substrate          ---> transform into coloured/fluorescent products          ---> detect activity of inserted genes Microarray identify genes present in an organism's genome find out which genes are expressed within cells        ---> microarrays contain thousands of gene probes 1. Genome analysis : compare genes present in two different species DNA collected from each species, cut to fragments and denatured ...

The polymerase chain reaction (PCR) and gel electrophoresis both work with molecules. Both these procedures are needed for forensic science. Polymerase chain reaction (PCR) - rapid production of a large number of copies of a particular DNA fragment DNA is denatured at 95 degrees Celcius --> separate DNA strands to expose bases attach primers to ends of single-stranded DNA at 65 degrees Celcius elongation : DNA polymerase builds new strands of DNA against exposed ones at 72 degrees Celcius         * Taq polymerase - 1st heat-stable polymerase used in PCR              - not destroyed in denaturation: no need to be replaced after each cycle              - high optimum temperature to maximize efficiency                    --> temperature doesn't need to be dropped for annealing process Gel electrophoresis  - to separate different molec...

Genetic engineering involves the manipulation of naturally occurring processes and enzymes. Recombinant DNA ( rDNA ): DNA made by joining pieces from two or more different sources Genetic engineering: extraction/syntheses  a gene(s) from one organism transfer gene(s) into another organism (of same or different species) --> gene is expressed in new host Plasmids as vectors in gene cloning Plasmids are small, circular pieces of double-stranded DNA small --> easy to use exist naturally in bacteria --> bacteria take up plasmids from surroundings can be produced artificially   double stranded: can insert genes from prokaryotes and eukaryotes replicate independently in bacteria can be transferred between different bacterial species Promoters  - control expression of genes --> ensure high levels of gene expression Promoter binds to DNA strand allows RNA polymerase to bind to DNA ensures RNA polymerase recognizes which is the template strand ---> promoter r...

19.1 Principles of genetic technology 19.2 Genetic technology applied to medicine 19.3 Genetically modified organisms in agriculture The discovery of the structure of DNA by Watson and Crick in the early 1950s and discoveries since have led to many applications of gene technology in areas of medicine, agriculture and forensic science. This section relies heavily on prior knowledge of DNA structure and protein synthesis studied in the section on Nucleic acids and protein synthesis. Where possible, candidates should carry out practical work using electrophoresis, either with DNA or specially prepared dyes used to represent DNA or proteins.  Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts. Learning outcomes  Candidates should be able to: 19.1 Principles of genetic technology  Genetic engineering involves the manipulation of naturally occurring processes and enzymes.  Genome sequencing gives in...

 1 Gene technology involves altering the genes in an organism, which is then said to be genetically modifi ed.  2 The usual way of genetically modifying bacteria is to insert a plasmid containing the desired gene into them.  3 The steps involved in the production of bacteria capable of synthesising human insulin are:    identifying the human insulin gene;    isolating mRNA and making cDNA using reverse transcriptase;    cloning the DNA using DNA polymerase;    inserting the DNA into a plasmid vector using restriction enzymes and DNA ligase;    inserting the plasmid vector into the host bacterium;    identifying the genetically modifi ed bacteria;    cloning the bacteria; and harvesting the human insulin.  4 The main advantage of treating diabetics with human insulin produced by gene technology is that it is chemically identical to the insulin that they would have produced had they not been diabetic...