LGS A-Level OCR Biology - Unit 6 - Cloning and Biotechnology
Clones are organisms or cells that are genetically identical, produced from the same original DNA. They arise naturally (e.g., identical twins, asexual reproduction) or artificially through biotechnological methods.
Clones
Carry identical genetic material because they are derived from the same orig. DNA
Key Terms
Clones
Carry identical genetic material because they are derived from the same orig. DNA
Cloning
Process of producing genetically identical cells or organisms from the cells of existing organisms through nonsexual means
Examples of processes that form genetically identical organisms
Mitosis
Binary fission (bacteria)
Budding (yeast)
Natural plant cloning
Vegetative propagation through runners or suckering
Artificial plant cloning
Artificial vegetative propagation through cuttings or micropropagation (tissue culture)
Vegetative propagation
Ability of plants to reproduce w/out sexual reproduction by producing new plants from existing vegetative structures
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| Term | Definition |
|---|---|
Clones | Carry identical genetic material because they are derived from the same orig. DNA |
Cloning | Process of producing genetically identical cells or organisms from the cells of existing organisms through nonsexual means |
Examples of processes that form genetically identical organisms | Mitosis Binary fission (bacteria) Budding (yeast) |
Natural plant cloning | Vegetative propagation through runners or suckering |
Artificial plant cloning | Artificial vegetative propagation through cuttings or micropropagation (tissue culture) |
Vegetative propagation | Ability of plants to reproduce w/out sexual reproduction by producing new plants from existing vegetative structures |
Vegetative structures | Non-reproductive tissues e.g. roots, leaves and stems |
Cuttings | Cut stem 1/4 “ below internode at 45-60 degrees Treat cut end w/ rooting hormones Cover in clear plastic bag Transfer to another growing medium |
Why do you cover cuttings w/ a clear plastic bag | To keep it moist and warm |
Explant | A small piece of tissue |
Callus | Undifferentiated mass of tissue containing totipotent cells |
Micropropagation | Cut out explant from vegetative structures (leaf) Sterilise explant w. alcohol Place explant in sterile agar w/ glucose, cytokinins and auxins Subdivide callus and place on growth medium to induce root growth (prepares plant for transplanting) Transferred to greenhouse to acclimatise before being planted outside |
Advantages of artificial plant cloning | Can produce large no. v. quickly Can grow plants that dont reproduce easily No need to wait for seed production Reproduce sterile plant |
Disadvantages of artificial plant cloning | Labour intensive and requires skilled workers Trial and error to find ideal conditions for growth Undesirable traits also passed on Can fail to microbial contamination |
Runners | Side stem grows out from bud at the base of the main stem Creates new bud and grows a vertical stem |
Suckering | Grow from shallow roots from buds that are normally dormant Duing times of stress, buds are activated and suckers form many metres away from parents tree (to avoid stress that triggered growth) Eventually form clonal patch of new trees Trees in clonal patch put out new sucker buds |
Advantages of natural plant cloning | Large colonies can form quickly Allows species to survive catastrophic events |
Disadvantages of natural plant coning | No natural selection Susceptible to gentic disease; no variation |
Runners vs. suckers | Runners are overground and suckers are underground |
Why must the agar used in micropropagation be sterile | Prevents infection Competition of resources e.g. oxygen/nutrients if other organisms e.g bacteria and fungi are present |
Somatic cell | Biological cell forming the body of an organism |
Germline cell | Biological cell that gives rise to the gametes of an organism that reproduces sexually |
Natural animal reproductive cloning | Some animals can regenerate entire animals from fragments of the orig. (starfish) Others fragment and form new identical animals as part of their normal reproductive process (flatworms and sponges) MZ twins form when an early embryo splits and and two foetuses develop from two halves |
Artificial animal reproductive cloning | Somatic cell nuclear transfer Artificial twinning |
Somatic cell nuclear transfer | Extract nucleus from somatic cell from Sheep A Remove nucleus from egg cell from Sheep B Insert nucleus from A into innoculated egg(electrofusion) Stimulates to divide in vitro and implant embryo into sheep C |
Artificial embryo twinning | Get fertilised egg and allow to divide until 16 cell stage Harvest embryo and split into smaller ones manually Implant into surrogate mothers which give birth to identical high quality animals |
Advantages of artifical animal cloning | Produce identical clones w/ desirable traits Stem cell research Clones so offspring can be produced all year round |
Disadvantages of artificial animal cloning | Difficult and time consuming Destruction of embryos unethical Clones have shorter life expectancies No genetic identity so selection pressures affects all |
Similarities between AT and SCNT | Produce clones Both have surrogates Divides by mitosis Unnateral Expensive |
Differences between AT and SCNT | AT forms several clones at once Gametes meet outside the body is AT SCNT involves only maternal DNA No fertilisation in SCNT |
Biotechnology | Industrial exploitation of living micro-organisms (or parts of them) and biological process to produce useful substances for human use |
Why are microorganisms used in biotech | Easy/ not labour intensive Obtain pure products if aseptic technique is followed Can be easily genetically enginerred to produce spp products Short life cycle Simple requirements for growth - can be left w/ little intervention Can be grown v. quickly Can be grown on waste material from other processes |
Use of microorganism in biological processes | Brewing - anaerobic respiration of yeast Baking - yeast Cheese making - bacteria and rennin Penicillin production - fermentation by fungus Insulin production - GM bacteria Bioremediation |
Bioremediation | Using microorganisms to clean up pollution | Convert toxic pollutants to less harmful substances |
Advantages of bioremediation | Uses natural systems Less labour and equipment required Treatment can be carried out on site Few waste products produced Less risk of harmful exposure to clean-up personnel |
Culturing microorganisms | Sterilisation - Sterilising equipment in an autoclave (15 mins at 121 degrees) Inoculation - Introducing a sample of microorganisms to the growth medium Incubation - Place in a warm environment and place agar plate upside down (condensation) |
Types of growth medium | Agar jelly in a petri dish | Nutrient broth in a bijoux bottle |
Standard procedure of aseptic techniques | Wash hands thoroughly Disinfect working area Light and keep Bunsen burner on Flame neck of bottle before and after taking sample Lift lid of petri dish slightly to introduce microbe by streaking Close petri dish and tape (not completely) Flame all equipment after use Wash hands again |
Why do you keep the Bunsen burner on during aseptic procedures | Heats the air, causing it to rise so air-borne microbes don't settle |
Why cant you seal the petri dish completely | Introduces O2 for aerobic respiration | Doesn't introduce harmful anaerobically respiration organism |
Continuous culture | Culture is set up and nutrients are added and products removed from the culture at intervals - done at same rate to keep vol constant Culture is maintained at exponential growth phase - grows and produces metabolites faster |
Metabolites | Substances produced by living organisms in order to survive e.g ATP synthase |
Batch culture | A starter population of the microorganism is given a fixed amount of nutrients and at the end of the time period products are extracted |
Examples of continuous culture | Insulin | Single-cell protein (from Fusarium) |
Examples of batch culture | Wine Beer Yogurt |
Advantages of continuous culture | Fermenter is always in use - increases efficiency High growth rate as nutrient levels maintained Useful for primary metabolites |
Disadvantages of continuous culture | Contamination is more likely Difficult to maintain and control product consistency In cases of contamination losses are great and all production halts |
Advantages of batch culture | Less likelihood of contamination Can be left for a set time period Useful for secondary metabolites In the event of contamination, only one batch is lost |
Disadvantage of batch culture | Fermenter isn't in use constantly - less efficient | Time spent cleaning |
Primary metabolites | Produced in the course of normal metabolism e.g. proteins, enzymes, alcohol Produced in lag and log phase |
Secondary metabolites | Produced after main population growth has occurred, nutrients are in short supply and population isn't growing rapidly Produced in stationary and death phase |
How do fermenters maximise the yield | Tube for sterile air to provide oxygen for aerobic reactions Sparger - diffuses air through culture medium Powerful motors - mixes contents ensuring equal distribution of nutrients and so microbes don't settle at base of fermenter Acid-base injection site - controls pH Culture broth - contains sources of carbon and nitrogen (NH3) and vitamins/minerals Jacket - filled with hot/cold water to provide optimum temp as respiration releases heat (denaturing) |
Asepsis in fermenters | Washing. disinfecting and steam cleaning all equipment Using fermenter made of polished stainless steel so microbes cant stick Sterilising all nutrients w/ steam or heat Only bubbling in sterile air- v. fine filters |
Phases in microorganim growth curves (bacteria/fungi) | Lag Exponential Stationary Death |
Lag phase | Reproduction v. slow as cells acclimitase, absorb nutrients Gene expresion for spp enzymes Synthesis of enzymes and organelles |
Exponential phase | Reproduction is rapid No limiting conditions Few cells die |
Stationary phase | Population remains constant as death and reproduction rates are the same |
Death phase | Lack of resources | Build up of CO2 - fatal |
Culture | A method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled lab conditions |
Isolated enzymes | Taking enzymes out of microorganism |
Issue w/ isolated enzymes | Product must be seperated from enzymes and extraction is v. expensive |
Immobilised enzyme | Enzymes fixed to a surface and do not freely mix w/ the substrate |
Ways to immobilise enzymes | Covalent bonding Encapsulation Adsorption Entrapment |
Covalent bonding to immobilise enzymes | Covalently bonded to a supporting surface | Enzymes are also covalently bonded together using a cross-linking agent |
Adsorption | Bound to supporting surface by a combination of hydrophobic interactions and ionic links Bound w/ active site exposed and accessible to substrate |
Entrapment | Trapped in a matrix (often calcium alginate beads) that doesn’t allow free movement |
Encapsulation/membane separation | Separated from reaction mixture by a small permeable membrane - microcapsule |
A vs D of adsorption | Simple and cheap Can be used in a variety of processes Enzymes v. accessible May distort active site Enzymes can detach and leak into reaction mixture |
A vs D of covalent bonding | Enzyme less likely to become detached pH and substrate conc have little effet on enzyme activty Accessible to substrate Expensive Can distort active site, reducing activity |
A vs D of encapsulation | Relatively simple Relatively small effect on enzyme activity Widely apllicable to diff processes Expensive Substrate and product has to be small in order to diffuse through partially permeabe membrane Diffusion is slow |
A vs D of entrapment | Widely applicable to diff processes May be expensive Difficult to entrap Effect of entrapment on enzyme activity dpends on the matrix Substrate and product needs to be small |
Examples of immobilised enzymes | Glucose isomerase Penicillin acylase Lactase Aminoacylase Glucoamylase Nitrile hydratase |
Penicillin acylase | Converts naturally produced penicillins to semi-synthetic penicillins Some resistant microorganims arent resistant to semi-synthetic penicillins |
Glucose isomerase | V. commonly use to produce HFCS, sweeter than sucrose and can be used in diet fods Glucose ---> fructose |
Lactase | Hyrolyses lactose into glucose and galactose so lactose-intlerant people can drink milk and reduce the risks of developing osteoporosis as a lack of calcium |
Aminoacylase | N-acyl-amino acids ---> pure sample of L-amino acids | Used in synthesising pharmaceutical compounds |
Glucoamylase | Dextrins ---> glucose | Immobilised and used to digest sources of starch e.g. corn and cassava |
Nitrile hydratase | Nitriles ---> amides Acrylamide can be polymerised to form a plastic and a gel for electrophoresis Used to treat water, helps to stick many small contaminanrts together so they can be filtered out |
Supporting surfaces | Glass Porous carbon Clay |
Advantages of immobilising enzymes | Lowers temp required No contamination of end product Reusable Protected by immobilisng matrix so high temp or extreme pH has no effect |
Disadvanages of immobilising enzymes | Expensive to set up Bonding may affect active site Contamination is v. costly as whole system needs to stop Slower process as enzymes and substrates don't mix freely |
Making yoghurt | Milk is fermented by bacteria Lactose---> lactic acid Low pH denatures caesin, causing milk to coagulate and thicknes Also adds flavour |
Makng cheese | Milk is fermented by bacteria Lactose --> lactic acid, acidifies milk Rennin coagulates caesin in the presence of Ca2+ Resulted curd separates from liquid whey by curdling, stirring and heating |
Microorganisms in baking | Flour is mxed w. water, salt and yeast | Respires anaerobically and produces CO2 bubbles, causing the dough to rise |
Making wine | Grapes have yeast on the surface | When crushed uses glucose and fructose to respire and produce CO2 and alcohol |
Making beer | Uses malted barley grains that are beginning to germinate Stored starch to maltose, respiratory substrate for yeast Produces CO2 and alcohol |
Making penicillin | Fermentation of fungus as a batch culture for 6-8 days Secondary metabolite Once fermentation is complete, culture is filtered to remove cells Antibiotics precipitated and purified |
Making insulin | Genetic modification of bacteria | Grown in fermenters, continuous culture |
Why is the Sheep C treated w/ hormones | Increase thickness and vascularisation of uterine lining |
How can SCNT help save endangered species | Doesn't require fertile females Female not put at risk during mating Can subdivide successfully formed embryo |
Economic advantages of immobilising enzymes | Reusable so less money required | Higher temp means profit from faster yield |