(6) Cloning and Biotechnology Flashcards
Natural clones in plants
Vegetative propagation - perennating organs which enables plants to survive adverse conditions.
Bulbs, runners, rhizomes, tubers.
Roots containing meristems which can divide by mitosis to produce root suckers, if the main trunk is destroyed a ring of root suckers starts to grow
Horticulture - cutting stem and treating with plant hormones to grow roots, grafting (cut of stem inserted into groove on a different plant stem), splitting bulbs.
Use a non flowering plant so resources are only used to grow the roots.
Make oblique cut with sharp scalpel to prevent damage and creates large surface area.
Use hormone rooting power to grow roots.
Reduce leaves to increase chance of survival.
Keep well watered as there is no roots.
Cover with plastic bag to increase humidity and prevent plant drying out, also reduces water loss.
Artificial cloning in plants
Tissue culture - making large numbers of genetically identical offspring from a single parent plant.
May be used for plants that do not readily produce seeds, do not respond well to natural cloning, rare plants, genetically modified or plants that need to be pathogen free.
Explant cells removed from meristem, cells are sterilised and placed on nutrient agar with cytokinin and auxin to stimulate mitosis. Grow into undifferentiated cells (callus), which is then subdivided and grown on nutrient agar with auxin. This stimulates differentiation to produce thousands on mini plants (plantlets) which are transferred to soil.
Evaluation of artificial cloning in plant
Strengths - small sample to produce crops grown independent from season, disease free crops, crops with desirable characteristics, plants that are difficult to grow. Conservation of rare species.
Limitations - expensive as it needs sterile conditions, using lab trained staff. Plantlets are vulnerable to mould. Monoculture = genetic uniformity so entire crops can be lost to disease.
Cloning animals naturally
Sexual reproduction - the egg may split after fertilisation during the very early stages of development. Causes them to develop into multiple embryos with the same genetic information.
Identical twins
Artifical cloning in animals
Splitting embryos - animal embryos contain totipotent stem cells.
Collect eggs and in vitro fertilisation.
Split embryos are implanted into surrogate mothers, each one is genetically identical.
Somatic Cell Nuclear Transfer (SCNT) - nucleus removed from the differentiated cell of a donor adult. Nucleus is placed into an enucleated egg cell, then implanted into surrogate mother. Develops into new individual which is genetically identical to donor adult.
Evaluation of artificial cloning in animals
Strengths - high production of large numbers of high value animals.
Replacing pets (racehorses), preservation of rare or endangered species, potential to reproduce extinct animals.
Limitations - animal welfare, reduced lifespan, failed embryos, genetic uniformity.
Use of microorganisms in biotechnological processes.
Have a short life cycle, so grow rapidly. Often produce proteins or chemicals that are given out into the surroundings which can easily be harvested.
Can be genetically engineered to produce specific products (insulin).
Grow well at low temperature (lower than required in chemical engineering) so economical.
Can grown anywhere - not dependent on climate
Baking (bread) - yeast respires anaerobically, carbon dioxide makes bread rise.
Brewing (beer) - Yest respires using the glucose to produce ethanol and co2 (fermentation).
Cheese making - yeast cells genetically modified to produce chymosin to clot the milk, separated into whey and curd, then fungi added for flavour.
Yoghurt production - lactobacillus clots milk and causes it to thicken.
Quorn made from fungus hyphae - similar length and width to muscle fibres
Evaluation of using microorganisms to make food for human consumption
Strengths - reproduce fast, high protein and little fat, using waste materials which reduces cost, can be genetically modified, production can be increased or decreased to match demand, no welfare issues, taste can be changed.
Limitations - may produce toxins, microorganisms have to be separated from nutrient broth, needs sterile conditions (expensive), concerns about eating gm food, little natural flavour.
Biotechnology in medicines and bioremediation
Penicillin was produced by mould, needs high o2 levels and rich nutrient medium to grow, also sensitive to pH and temperature - must be controlled.
Insulin - genetic engineered bacteria, grown in fermenters and downstream processing = constant supply.
Bioremediation - use of organisms to remove toxic materials from the environment. Used to remove pollutants like crude oil and sewage - given extra nutrients to allow them to multiply.
Culturing microorganisms
Microorganisms must be cultured to investigate them for medical diagnosis or for scientific experiments.
Need food provided by nutrient medium, either as a broth or agar - using a wire inoculation loop and spreader. Temperature, o2, pH must be controlled.
Must be aseptic because contaminants reduce the product yield by : competing with wanted microorganisms, causing spoilage, producing toxic chemicals, destroy wanted microorganisms.
Flaming - heat metal loops for transferring organisms.
Irradiation - UV and gamma rays used on vessels.
Autoclave - steam sterilisation.
Laminar flow cabinet - air circulation carries air borne contaminants away.
Keep cultures closed - do not place lids on benches, flame neck of tubes.
Fermentation vessel
Pressure vent - prevents gas build up.
Air inlet - supplies o2 for aerobic respiration (sterile).
Water jacket - controls temperature.
Motor and mixing blades - mix culture evenly.
Nutrient inlet.
Electronic probe - measure o2, pH, temperature.
Air outlets - mixes are with culture (sparging).
Harvest outlet - collect product.
Batch culture
Microorganisms grow in a fixed volume of nutrient medium for a fixed period of time, then product is removed at the end.
Only o2 is added.
Only co2 is removed.
Microorganisms go through lag, exponential and stationary phase.
Continue to grow until conditions become unfavourable.
Used for obtaining secondary metabolites - antibiotics from fungi.
Continuous culture
Nutrients added and products are removed continuously.
Fresh sterile medium is added and cells and spent medium are removed at the same rate.
Kept in exponential stage, so number of cells is kept fixed.
Continue to grow indefinitely.
Used to obtain primary metabolites - human insulin from GM bacteria or proteins for quorn).
Cannot be used to get antibiotics because they are a secondary metabolite which is made in the stationary phase.
Manipulating growing conditions in fermentation
pH - monitored by probe - allows enzymes to work efficiently so rate of reaction is as high as possible.
Temperature - controlled by water jacket which surrounds the vessel - allows enzymes to work efficiently so rate of reaction is as high as possible.
Access to nutrients - paddles circulate fresh nutrient medium around the vessel - ensures microorganisms always have access to their required nutrients.
Volume of oxygen - sterile air is pumped into the vessel when needed - makes sure that the microorganisms always have fresh o2 for respiration.
Vessel kept sterile - heated steam sterilises the vessel after each use - kills any unwanted organisms that may compete with the ones being cultured.
Allows yield of product to be maximised
Growth curve of a microorganism in closed culture
Lag phase - organisms adjust to surroundings, cells are not reproducing but are active.
Exponential phase - population size doubles each generation as every individual have enough space and nutrients to reproduce.
Stationary phase - waste products build up. o2, nutrients and space run out so the rate of reproduction is equal to the rate of death.
Death phase - nutrient exhaustion and increased build up of toxic waste products and metabolites leads to increased death rate. Deaths are higher than reproduction rate.
