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B5.2 - Biotechnology
Biotechnology - OCR A2 Biology
| Question | Answer |
|---|---|
| Define Clone: | A genetically identical organism. |
| Advantages of Asexual reproduction: | Quick. Can be completed if sexual cannot. All offspring have the Genetic Information to enable survival. |
| Disadvantages of Asexual reproduction: | No genetic variation. |
| Define vegetative propagation: | The production of structures in an organism that can grow into new individual organisms. |
| What is an Example of vegetative Propagation: | Root suckers produced by healthy Elm trees. |
| What does 'Taking Cuttings' involve? | A section of stem is cut between leaf joints. The cut end is then treated with plant growth hormones to encourage root growth and planted. |
| What does 'Grafting' involve? | A shoot section of a woody plant is joint to an already growing root and stem. this is genetically identical to the parent plant, but the rootstock is genetically different. |
| Describe Micropropagation by Tissue Culture: | Small piece of tissue called the Explant is removed. Place on nutrient growth medium. Forms a mass of undifferentiated cells called a Callus. Sub-divide callus. Place on Shoot and Root growth medium. Place in greenhouse, and then plant outside. |
| Advantages of plant cloning in Agriculture: | Costs reduced as all the crop is ready to harvest at the same time. They know what the crop plant will be like. Faster than selective breeding. |
| Disadvantages of plant cloning in Agriculture: | Genetically identical, so all susceptible to disease of environmental change. |
| Describe cloning by 'Splitting Embryo's': | High-value organisms egg and sperm cells are collected. Fertilised In Vitro. Embryo produced is split into several seperate segments. Implanted in surrogate mother. |
| Describe cloning by 'Nuclear Transfer': | Body cells are removed from one organism, and an egg cell from another. Egg cell is enucleated and combined with the body cell via electro-fusion. Left to culture in 'tied oviduct' of organism. Embryo removed and implanted in surrogate mother. |
| Advantages of Animal Cloning: | High-value animals can be cloned in large numbers. Rare animals can be cloned to preserve the species. Genetically modified animals can be reproduced in large numbers. |
| Disadvantages of Animal Cloning: | High-value animals are not necessarily cloned with animal welfare in mind (e.g. being unable to walk). Genetic uniformity makes them all susceptible to disease or environmental change. Cloned animals may live shorter lives. |
| What is Non-Reproductive cloning? | Using cloned cells to generate cells tissues and organs to replace those damaged by disease or accidents. |
| Advantages of Non-Reproductive cloning: | Genetically identical, so will not be rejected. Don't have to wait for a donor. Can be used to generate any type of cell as they are Totipotent. |
| Define Biotechnology: | Technology based on Biology and involves the exploitation of living organisms or biological processes, to improve Agriculture, food science, Medicine and Industry. |
| Why are Microorganisms often used in Biotechnological processes? | Grow rapidly in favourable conditions, can be engineered to produce specific products, can be grown anywhere regardless of climate, gan be grown using waste materials, purer products. |
| What is a Primary Metabolite? | Substances produced as a part of an organisms normal growth. (e.g. Amino acids, Proteins, Enzymes) |
| What is a Secondary Metabolite? | Substances produced not as a part of an organisms normal growth. (e.g. Penicillin) |
| What happens during the Lag phase? | Organisms adjusting to surroundings. Cells are active but not reproducing. Population = fairly constant. |
| What happens during the Log (exponential) Phase? | Population size is doubling each generation. Occurs until nutrients are depleted and space has run out. |
| What happens during the Stationary Phase? | Nutrient levels decrease and waste products build up. Rate of reproduction = rate of death. |
| What happens during the Death/Decline Phase? | Nutrients have run out, and toxic waste product concentration has increased to a point where the rate of death > rate of reproduction. |
| What conditions need to be controlled in a fermenter? | Temperature, pH, Oxygen concentration. |
| What is a batch culture? | Microorganisms are mixed with a specific quantity of nutrients, and left to grow for a fixed period. The products are then removed and the fermenter emptied. |
| What is a continuous culture? | Nutrients are added to the fermentation tank and products removed at regular intervals. |
| Why is the growth of unwanted microorganisms bad in a fermenter? | Compete for nutrients and space. Reduce yield of useful products. May spoil the product. Produce toxic chemicals. Destroy culture microorganisms. |
| Define Asepsis: | The absence of unwanted microorganisms. |
| What is immobilisation of enzymes? | The enzymes are held, separated from the reaction mixture. |
| Advantages of Immobilising enzymes: | Enzymes are not present with products, so purification costs are lower. Enzymes immediately available for re-use. Enzymes more stable. |
| Disadvantages of Immobilising enzymes: | Requires additional time, equipment and materials and so is more expensive. Enzymes may be less active. Contamination is costly to deal with as the whole system must be stopped. |
| Describe Immobilising enzymes via 'Adsorption': | Enzymes are mixed with an immobilising support, and bind to it via hydrophobic interactions and ionic links. |
| Describe Immobilising enzymes via 'Covalent Bonding': | Enzyme molecules are covalently bonded to a support. Very little linkage of enzyme from the support. |
| Describe Immobilising enzymes via 'Entrapment': | Enzymes may be trapped, for example in an Alginate bead, in their natural state. Substrate molecules must get through the trapping barrier to access the active site. |
| Describe Immobilising enzymes via 'Membrane Separation': | Enzymes are physically separated from the reaction mixture by a partially permeable membrane. |
| Define Genomics: | The study of the whole set of genetic information in the form of the DNA base sequences. |
| Describe the sequencing of the genome of an organism: | Genomes are mapped to identify which part of the genome they have come from. Samples of the genome are sheared (broken up) and placed into BACs and transferred into E. cool cells. These are then cut with Restriction Enzymes, and sequenced automatically. |
| Why is the ability to compare genomes useful? | Genes or proteins found in many living organisms suggest they're important for life. Shows evolutionary relationships. Checking for mutant alleles. |
| What is a DNA probe? | A short single-stranded piece of DNA. It is labelled (either radioactively, or with a flourescent marker). |
| Describe Electrophoresis: | Samples of DNA are cut with restriction enzymes. These are placed in wells at one end of the agar gel. An electric current is passed through the gel. DNA is negatively charged so will move towards the anode. Shorter lengths of DNA will get further. |
| What is a Primer? | Short-single stranded lengths of DNA. They are needed, in sequencing reactions and PCR to bind to a section of DNA. |
| Describe PCR: | DNA sample mixed with DNA nucleotides and DNA polymerase. Heated to 95ºC to break the Hydrogen bonds between bases. Primers are added. Temperature reduced to 55ºC, primers bind to ssDNA. DNA polymerase binds to ssDNA. Temp = 72ºC. DNA reformed by enzyme. |
| Define Recombinant DNA: | DNA that has been combined from two different sources, in a single organism. |
| How can DNA be recombined using DNA Ligase and Restriction Enzymes? | Restriction enzymes cut DNA at a specific point, leaving a complimentary sticky end. To join separate fragments, DNA ligase is used to bind the two sugar-phosphate backbones. (This happens after the complimentary bases have joined with Hydrogen bonds) |
| What is a Transgenic organism? | Any organism that contains DNA that has been added to it's cells as a result of genetic engineering. |
| What are the two reasons for carrying out genetic engineering? | Improving a feature of the recipient organism. Engineering organisms so that they can produce useful products. |
| How do bacterial cells take up Plasmid DNA? | Mix the plasmid and the bacterial cells together. Add calcium salts and 'heat shock' the mixture. (Raise the temperature from 0 to 40ºC very quickly) |
| Describe Bacterial conjugation: | A conjugation tube forms between two bacterial cells. Plasmid replication begins and the free strand begins to move through the tube. In the recipient cell replication begins. The cells then move apart and the plasmid in each forms a circle. |
| What are the advantages to bacterial cells in being able to take up new DNA? | Passing on Antibiotic resistance. Contributes to genetic variation. |
| Describe the process involved in the genetic engineering of bacteria to produce the human insulin gene: | mRNA strand is retrieved from pancreatic tissue and the enzyme Reverse Transcriptase used to produce a complimentary DNA strand. DNA polymerase and free DNA nucleotides are added to form the double strand (cDNA). |
| Describe how this human insulin gene is then used to produce insulin: | Plasmids are cut open with a restriction enzyme, and mixed with the cDNA genes. Plasmids take up the gene, and the sugar-phosphate backbone is sealed with DNA ligase. These are then mixed with bacteria, which when grown will produce insulin. |
| Describe the process of identifying transformed bacteria via the process of Replica Plating: | Original plasmids carry genes that make bacteria resistance to two antibiotics. Plasmids are cut through one of the genes for these antibiotics so it won't work. Cells are then placed on agar containing chemicals, those that survive have the gene. |
| Why is a deficiency of Vitamin A bad? | Functions of Vitamin A: eyesight, cell growth and development, epithelial tissue, bone growth. |
| Why is the use of genetically modified crops 'unacceptable'? | Reduction in genetic biodiversity. Whether the food is safe or not is relatively unknown. Could breed with wild rice and contaminate it. |
| What is gene therapy? | The treatment of genetic disorders using genetic technology. |
| What is somatic cell gene therapy? | A working copy of the gene is inserted into the body cells, so that the functioning polypeptide is transcribed. |
| What is Germline cell therapy? | Engineering a gene into a sperm or egg cell, meaning that every cell in the organism contains a working copy of the gene. This gene can now function in any cell that it is required. |
| State some differences between Somatic and Germline cell therapy? | Somatic therapy only provides short lived treatment, Germline therapy is permanent. Somatic therapy will not pass the gene on to the offspring, Germline therapy will. |
| How will genetic engineering help with the transplantation of organs? | It will provide a genetically identical organ to the patient so won't be rejected. Will remove the need to wait for a donor. |
Created by:
Sparksy
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