4382069
Description
Flashcards by David Alty, updated more than 1 year ago
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Created by David Alty
almost 9 years ago
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| Question | Answer |
| Describe how negative feedback controls: Temperature, Glucose and salt | Temperature: Thermoregulatory centre in hypothalamus -> effectors Glucose: Pancreas (a-cells + B-cells) detects and responds to change Salt: Osmoreceptors in hypothalamus -> neurosecretory cells (specialised neurones) ADH->Posterior pituatary gland |
| advantages ectotherms v. endotherms | ectotherms: +less energy, survive in hot - less agile, inactive at night, rely on sun endotherms: +constant body temp, more agile, many environments, can nocturnal -higher energy consumption |
| deal with environment ectotherms and endotherms | Ectotherms: Move!, horned lizard increase surface, hide in burrow, locusts breathe Endotherms: Sweat glands, panting, hairs on skin, skin capillaries (vasodilation+ vasocontriction), liver cells (metabolism), Skeletal muscles |
| Control of insulin secretion | Blood glucose^ -> glucose metabolised (Glucokinase) to ATP -> closes potassium channels -> calcium open -> insulin exocytosed [at rest -70mV] |
| Pancreas: exocrine v. endocrine | Exocrine: Pancreatic duct-> amylase, trypsinogen (protease), lipase Endocrine: Islets of Langerhans a-cells glucagon, B-cells insulin |
| Describe action potential | 1. rest = polarised -60 mV 2. Sodium open 3. depolarise (threshold -50mV) 4. Voltage-gated sodium open 5. +40mV > sodium close, potassium open 6. potassium out-> repolarisation 7.overshoot (hyperpolarisation) |
| Receptors for: light, volatile chemicals, soluble chemicals, pressure, vibrations in air, length of muscle fibres... | retina (rods and cones), Olfactory (nose), taste buds, cochlea, muscle spindles (proprioceptors) |
| myelin sheath | insulating layer of fatty material (Schwann cells) -> have gaps (Nodes of Ranvier) -> diffuse node to node -> saltatory conduction |
| Synaptic knob -> synaptic cleft -> post synaptic membrane | Synaptic knob: [many mitochondria, smooth ER] Sodium -> calcium -> Acetylcholine -> synapse [acetylcholinesterase] -> membrane sodium channels open |
| Advantages of synapses: | -signals can converge -can diverge -correct direction -filter out low-level -summation -acclimatisation -conscious thought and memory |
| hormones and cyclic AMP | 2 types -proteins -steroids proteins cell surface -> convert ATP to AMP -> response Steroids can pass through |
| Adrenal medulla + Adrenal cortex | Adrenal medulla->adrenaline dilate pupils etc Adrenal cortex -> steroids -> mineralocorticoids sodium and potassium conc + glucocorticoids control metabolism |
| how does heart rate change? | Medulla oblongata [+stretch receptors +Low pH (CO2) -high blood pressure] blood-> +Adrenaline |
| Describe the gross structure of the liver | microvilli, sinusoid, kupffer cell = specialised macrophage red blood cells |
| Deamination | Urea ^<-ornithine cycle amino acid-> ammonia + keto acid |
| Ornithine cycle and why | -ammonia is toxic(pH) and soluble -urea less soluble less toxic |
| Detoxification of alcohol | -broken down in liver -enters respiration |
| Kidney structure (macro) | |
| Structure of the nephron | |
| Ultrafiltration | three layers: endothelium of capillary, basement membrane fine mesh of collagen (no proteins), podocytes (finger like) help flow of fluid |
| Proximal convoluted tubule | 85% of filtrate reabsorbed all glucose + amino acids (+ some salt) microvilli covered in co-transporter proteins (facilitated diffusion). Sodium-potassium pumps, many mitochondria |
| loop of henle | hairpin countercurrent multiplier descending = permeable ascending = impermeable ascending: sodium potassium pumps |
| Collecting duct | some water reabsorbed osmoregulation takes place here with ADH collecting duct covered in aquaporins which allows water to osmosise across ADH causes aquaporins to be removed (cell creates a vesicle round aquaporins) |
| Kidney failure | -Kidney transplant -haemodialysis -blood passed through machine (adds heparin to avoid clots) (removes bubbles) three times a week -peritoneal dialysis tube implanted in abdomen, dialysis poured in, drained after several hours |
| Pregnancy test | human chorionic gonadotrophin small glycoprotein found in pregnant women monoclonal antibodies attach and create blue line |
| Anabolic steroids | half-life of 16hrs remain in blood for while gas chromatography or mass spec specific retention time |
| Structure of chloroplasts | -double membrane -inter membrane space (10-20nm) -lamellae -> granum (thylakoids) [intergranal lamellae] -two regions stroma & grana -light inde -> stroma -light depend -> thylakoids |
| photosynthetic pigments | -P680 & P700 absorb red light -both also absorb blue P680=450nm P700=500nm640nm |
| Accessory pigments | Carotenoids help pass light to chlorophyll absorb other less absorbed wavelengths and pass energy to bottom |
| Light-dependent stage | cyclic- only P700 small amounts of ATP produced (guard cells) non-cyclic- uses both P700 & P680 |
| Light-independent stage | [stroma] CO2 diffuses in. 5 out of every six TP is recycled. Some GP make amino acids |
| limiting factors of Calvin cycle | light-dependant unsurprisingly relies on light. light levels \/ -> RuBP\/, TP\/ and GP^. CO2\/ -> GP\/, TP\/ and RuBP^. Temparature^(25c) Rubisco diminished slows photosynthesis. |
| The structure and use of ATP | hydrolysed to create Energy. Pi removed ATP->ADP->AMP-> adenosine |
| overview of respiration | lactate or ethanol fermentation ^anaerobic respiration glycolysis (glucose->pyruvate) \/link reaction-> krebs cycle-> oxidative phosphorylation |
| NAD structure | |
| CoA structure | |
| Glycolysis + products | |
| mitochondria structure + oxidative phosphorylation | |
| link reaction + krebs cycle | |
| Anaerobic respiration | lactate toxic and needs to be oxidised in liver. yeast kills itself at 15% alcohol concentration |
| energy value of different substrates | carbohydrate: (theoretical maximum) 2870kJ/mol 94mol of ATP only 30mol rest released as heat. mean 15.8kJ/g Protein: ornithine cycle -> krebs cycle slightly more ATP produced. mean 17kJ/g Lipids: triglyceride->glycerol+3fatty acids ->fatty acids produce many redNAD. 39.4kJ |
| describe transcription | -gene to be transcribed unwinds and unzips (hydrogen bonds break) -Activated RNA nucleotides bind to their exposed bases on the template strand -two extra phosphoryl groups released gives energy for adjacent bonds -mRNA is copy of coding strand |
| describe translation | -mRNA binds to ribosome, two codons attached to small subunit exposed to large (first always AUG) using energy tRNA with methionine (UAC) bonds -followed by next tRNA -peptides between amino acids -tRNA can be reused ribosome moves until it reaches UAA, UAC or UGA |
| types of mutations +effects | point mutations (substitution): less effect on tertiary structure could even be silent insertion/deletion (frameshift): likely to have large effect on tertiary |
| diseases associated with mutations | -70% of cystic fibrosis is a deletion -sickle-cell anemia results from a point mutation on codon 6 causes a valine instead of glutamic acid -protooncogenes (growth promoting) can turn into oncogenes which keeps them permanently on (cancer) -Huntingtons disease repeating CAD |
| inuits | get their vitamin D from seal blubbler |
| lac operon | |
| body development of drosophila fly | homeobox genes: maternal- genes determine embryo's polarity (head and tail) segmentation genes- polarity of segment homeotic selector genes specify each segment |
| developement in vertebrates | homeobox genes are arranged in Hox clusters round worms have 1 drosphila have 2 and vertebrates have 4 specify body plan. Retinoic acid (derivative of vitA) a morphogen and too much taken in during pregnancy can cause birth defects |
| apoptosis | 8-14: 20-30billion cells apoptosise adults: 50-70million |
| meiosis | prophase 1: chromatin supercoils form bivalent attach at chiasmata and crossing over. (all steps of mitsosis x2) |
| recessive epistasis | |
| dominant epistasis | |
| complementary epistasis | |
| best way of measuring energy transfer | productivity>energy>biomass>numbers 1. productivity: rate at which energy passes through each trophic level over time 2. pyramid of energy: no time 3. pyramid of biomass: only mass 4. pyramid of numbers; only numbers |
| gross primary productivity and net primary productivity | rate at which plants convert light energy into chemical energy net is the after what is lost through respiration is removed |
| succession | |
| nitrogen recycling | |
| population growth | lag: repro low death low log: repro high death low stationary: repro high death high |
| prey and predator population | |
| competition between bacteria | interspecific competition is between members of different species. Gause concluded that the more close the niche the more competition between species until one kills off the other. However, in the real world this is unlikely as many other things come into play |
| sustainable management | coppicing: trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level. pollarding: further up clear felling: whole forest (bad) selective cutting: only the best |
| conservation, why? | ethics: responsibility economic: genetic diversity may be useful many drugs derived from natural the environment . natural predators may control pests |
| management strategies for conservation | -raise carrying capacity with food -move individuals to enlarge populations -restrict dispersal of individuals by fencing -control predators and poachers -vaccinate individuals against disease -prevent pollution |
| Galapagos islands | learn da case study bs |
| Tropisms | Phototropism, Geotropism(gravity), Chemotropism, thigmotropism(wind around other plants) |
| How hormones in plants move | active transport, Diffusion, mass flow through phloem and xylem |
| Phototropism | auxin moves to shaded side of apical stem and causes elongation on that side and bend. Two enzymes identified phototropin 1 and 2 lots of 1 on the light side and progressively less to dark side |
| How does auxin work? | Auxin increases the stretchiness of the cell wall by promoting the active transport of hydrogen ions into the cell wall. The lowered pH activates enzymes which loosen the cell wall. The enzymes break bonds in the cellulose allowing the cell to expand and take in more water. |
| senescing | cytokinins make sure leaves act as sinks for phloem transport so they have a good supply if cytokinin levels drop however the supply of nutrients drop |
| hormones responsible for apical dominance | Abscisic acid(AA) inhibits bud growth. high conc of auxin in the shoot keep AA high. Once bud removed auxin and then AA drops. Cytokinins then promote bud growth. High auxin in the apical shoot make it a sink for cytokinin once the shoot is removed it spreads more evenly. |
| commercial uses for auxin | Cuttings- rooting powder contains auxin Seedless fruit- adding auxin to unpollinated flowers can promote growth of seedless fruit Herbicides- artificial auxins will stimulate growth and will not be compatible with enzymes meaning they will not be broken down |
| commercial uses for gibberellins | Fruit production- delay senescence in citrus fruit. improve apple shape. grape size can be increased. Beer- Added G breaks down the aleurone layer faster converting starch to maltose malt is then produced by drying and grinding up the seeds Sugar production- height=sugar Plant breeding- G can be used to induce seed production in juvenile coniferous tree allowing earlier breeding Flowers- G inhibitors stop the flower from bending over with the weight of the flower head. |
| commercial uses for cytokinins | Lettuce- C can be used to prevent yellowing of picked lettuce C can be used in mass producing plants as little cuttings can be exponentially increased |
| commercial uses for ethene | 2-chloroethylphosphonic acid is sprayed -Speeding up fruit ripening in apples, tomatos and citrus -promoting fruit drop in cotton, cherry and walnut -promoting female sex expression in cucumbers -promoting lateral growth in some plants |
| Structure of the brain | |
| Which parts of the brain is different information processed in? | |
| Central nervous fact | Consists of brain and spinal cord. Made up of grey matter (billions of non-myelinated) and white mater (longer, myelinated axons and dendrons) (makes it look white). |
| Somatic v. autonomic | Somatic neurones carry impulses from the CNS to skeletal muscles (voluntary control) Autonomic motor neurones carry impulses from the CNS to cardiac, smooth and glands (involuntary) |
| Autonomic neurones | Most autonomic nuerones are non-myelinated whilst most somatic neurones are myelinated. Autonomic connections always consist of at least two nuerones connect at a swelling known as a ganglion |
| Parasympathetic and sympathetic | parasympathetic- most active in sleep, pre ganglion neurones vary in length, acetylcholine as neurotransmitter, decrease heart rate, relax, etc sympathetic- active when stressed, pre ganglionic neurones are very short, noradrenaline as neurotransmitter, increase heart rate etc |
| difference between motor neurone and sensory nuerone | motor: away from CNS (to effector), longer axon, no dendron, cell body in CNS sensory: to CNS (from receptor), shorter axon, has dendron, cell body in CNS |
| structure of elbow | a synovial joint where large amount of movement required. fluid is lubricant |
| Control of muscle contraction | 1. impulse arrives at neuromuscular junction 2. acetylcholine binds to receptors on the muscle fibre membrane (sarcolemma) 3. depolarisation travels down tubules 4. t system depolarisation releases Ca2+ from specialised endoplasmic reticulum 5. acetylcholinesterase rapidly breaks down so contraction only occurs when impulse arrives continuously |
| The importance of motor units | allows for control of contraction as more motor units means larger response this is called the graduation of response |
| muscle stimulation | -a single stimuli leads to a twitch -stimuli close together can cause an overlap more powerful (summation) -repeated stimuli lead to tetanus |
| involuntary smooth muscle | walls of intestine- circular and longitudinal bundles- peristalsis iris of eye- circular and radial bundles- radial dilate, circular constrict arteries and cervix- circular bundles- temparature regulation, local blood pressure |
| cardiac muslce | atrial and ventricular muscle- similar to skeletal longer contraction myogenic muscles capable of stimulating contraction autonomic system carry impulses to the heart to regulate contraction |
| intercalated discs | found in the heart cell membranes fused to allow easy diffusion of ions and allow action potentials to travel very easily and quickly between cardiac muscle fbres. Heart is striated |
| voluntary muscle | leads to movement of skeletal joints. muscle cells form fibres of about 100um in diameter, containing several nuclei. each fiber is surrounded by a cell surface membrane called a sarcolemma. fatigues quickly. |
| structure of a muscle fibre | |
| structure of thin filaments | two strands of F actin coiled around each other. Tropomyosin coil around f actin reinforcing it. A tropinin binds to actin, tropomyosin and one for calcium ions. Once calcium binds the tropomyosin moves allowing the cross-bridge to form |
| structure of thick filaments | bundles of myosin protein. Each myosin consists of a tail and two protuding heads. |
| The power stroke | 1. myosin heads form cross-bridges 2. heads bend causing movement of thin filament (power stroke) ADP + Pi released 3. cross-bridge then broken new ATP attaches 4. head group moves back and forms another cross bridge as ATP is hydrolysed |
| ATP supply for muscle contraction | -aerobic respiration (CO2 conc causes more O2 to be produced) -anaerobic respiration production of lactic acid stimulates increased blood supply to muscles -Creatine phosphate found in sarcoplasmic reticulum allows further contraction of muscles for 2-4 seconds. The phosphate from creatine is transferred to ADP to form ATP from the action of the enzyme phosphotransferase |
| physiological fight or flight responses | -pupils dilate -hear rate increases -digestion slowed -blood glucose increases -metabolic rate increases -Erector pili muscles in the skin contract making hairs stand up -ventilation rate and depth increase -ventilation rate and depth increase -endorphins released -sweat production increases |
| coordination of physiological changes | threat percieved-> hypothalamus activated -> sympathetic nervous system -> adrenaline released (from the adrenal medulla) |
| dealing with stressors | hyopthalamus releases corticotropin-releasing factor (CRF) into the pituitary gland, stimulationg the release of the hormone adreno-coritcotropic hormone (ACTH) from the anterior pituitary gland. this stimulates many corticosteriod hormones to be released from the adrenal cortex some of which help to deal with stressors. |
| innate behaviour | -genetically determined passed on via reproduction -rigid and inflexible -patterns of behaviour is the same in all members of the species |
| learned behaviours | -not passed on via reproduction but taught -can be altered by experience -considerable variety shown between members of a species -form basis of intellectual activity |
| types of innate behaviour | -reflexes: involuntary reflexes -kineses: orientation behaviour movement however non-directional -taxes: directional movement |
| types of learned behaviour | habituation- over repeated exposure animals learn to ignore Imprinting- goslings learn from the parent and follow Latent learning- explore new surroundings for later use insight learning- think and reason |
| classical conditioning | Pavlov 1.unconditioned stimuli-> unconditioned response 2.neutral stimuli->no conditioned respose 3.combined stimuli-> unconditioned response 4.conditioned stimuli->conditioned response |
| operant conditioning | B.F. Skinner trial and error learning pressing leaver releases food leaver becomes associated with food. |
| Imporantance of social behaviours | -enhanced survival rate of young -learn from others vital in survival -growth of brain slows maturation of young -knowledge and protection of food sources is shared with the group -greater ability to deter predators is achieved by working together |
| DOpamine | a neurotransmitter and a hormone. precursor in the production of adrenaline and noradrenaline. Dopamine increases general arousal and decreases inhibitions which can increase impulsiveness such as gambling |
| dopamine and parkinsons | Abnormally low-levels of dopamine is associated with Parkinson's disease. The treatment of which is clinical administration of dopamine's precursor L-dopa. Unfortunately this can lead to the development of mental conditions such as schizophrenia. |
| ADHD | A condition associated with the an allele of the DRD4 receptor in the brain. Ritalin works by affecting dopamine levels in the brain |
| OCD | thought to be as a result from a deficiency in the levels of the neurotransmitter serotonin. A 2007 study linked eight genetic markers that appear to be linked to OCD were found |
| Advantages/disadvantages of asexual reproduction | +quick reproduce rapidly +if sexual reproduction fails +all offspring have genetic information to survive in their environment -No genetic variety all offspring genetically susceptible |
| Natural vegetative propagation in plants | Many plant species reproduce asexually following damage to the parent plant forming a new growth or basal sprout. |
| Dutch elm disease | spread through europe's elms the leaves wither followed by death this stimulates a clonal patch to form ,however, once the sprout reaches 10cm diameter it is infected and dies so no reproduction can occur and no natural selection. |
| Artificial vegetative propagation | -cuttings -Grafting -Tissue culture 1. explant taken (small piece) 2. explant placed on growth medium 3. cells divide bu do not differentiate instead form callus 4. after a few weeks single callus cells stimulated to form shoots 5. after a further few weeks the shoots are transferred and stimulated to produce roots 6. the growing plants are then transferred to a greenhouse |
| Cloning animals | totipotent stem cells -Splitting embryos: cells from a developing embryo can be separated out and entered into many surrogate mothers -nuclear transfer: adults cells from desired clone has nucleus removed, donor egg contents removed electrofused with nucleus, reconstructured cell entered into surrogate mother |
| dis/advantages of cloning animals | +high value animals can be cloned in large numbers +rare animals can be preserved +Genetically modified organisms can be quickly reproduced -high value animals may be lame -susceptible to genetic disease -unclear whether animals remain healthy in long term |
| theraupuetic cloning or non-reproductive cloning | could be used to replace damaged tissues or organs. -no rejection -no more waiting for donors -some cannot cured by transplant that totipotent cells could -less dangerous than a major operation |
| biotechnology | exploitation of lining organisms or biological processes, to improve agriculture, animal husbandry, food science, medicine and industry |
| examples of biotechnology | food -cheese and yoghurt-making -mycoprotein -naturally brewed soya sauce medicine -penicillin -Insulin enzymes -pectinase (fruit juice extraction) -calcium citrate (detergent) -biogasfuel production waste water treatment |
| why use microorganisms in biotech | _grow rapidly -easily harvested -genetically engineered -grow well at relatively low temperatures -not dependent on climate -higher purity -grown using nutrient that would otherwise be useless or toxic |
| standard growth curve | lag phase; adjusting to surroundings Log phase; exponential growth stationary phase; organisms die at the same rate as generation decline phase; nutrient exhaustion/toxic waste buildup |
| primary metabolites and sec ondary metabolites | primary follow the growth cure secondary produced separate from the curve produced after growth e.g antibiotics |
| batch culture and continuous culture | batch culture: microorganism starter population is mixed with specific quantity of nutrient solution left and once the organism dies harvested continuous culture: nutrients are added to the fermentation tank and product removed |
| Asepsis techniques | Starter culture: all apparatus sterile use of fume cupboard cultures keep closed where possible large scale culture: disinfecting fermenter. fine filters on inlet and outlet |
| reasons for asepsis | -compete withe culture micro organisms for nutrients and space -reduce yield of useful product -spoilage of product |
| dis/advantage of batch/continuous | batch; -growth rate slower +easy to set up +contamination ruins only one batch -less efficient +very useful for producing secondary metabolites continuous; +growth rate higher -set up/maintenance difficult to achieve -contamination may ruin everything +efficient +useful for producing primary metabolites |
| downstream processing | separation or purification of any product of large scale fermentations |
| dis/advantage of immobilising enzymes | +enzymes not present with products +immediately available for reuse +increases enzyme stability as they are protected by matrix -expensive set up -can be less active not free -any contamination is costly |
| methods for immobilising enzymes: Adsorption | enzymes bind to support molecules sucha s porous carbon, glass beads, clays and resins. adsorption occurs through a mixture of hydrophobic and ionic bonds as the bonds are not particularly strong they can detach known as leakage. As long as still attached give very high rate of reaction |
| methods for immobilising enzymes: covalent bonding | covalently bonded to support usually using a linking agent like glutaldehyde or sepharose as bonds are very strong very little leakage occurs |
| methods for immobilising enzymes: entrapment | enzymes trapper in a gel bead or a network of cellulose fibres. active site is not affected as the enzymes are not bound to anything. However, reactions rate are reduced as the substrate must travel through the barrier to the active site. |
| methods for immobilising enzymes: membrane separation | enzymes held on one side of a membrane and unable to pass to the other side whilst the substrate does and the product can travel back. does require small substrate and product |
| manipulating DNA | -DNA strands cut up via endonuclease enzymes -fragments separated via electrophoresis and replicated via polymerase chain reaction. -DNA fragments anaylsed for sequence. -DNA probes can be used to locate specific sequences on DNA fragments -Fragments can be sealed together using ligase enzymes -DNA probes can locate specific sequences |
| genomics | the study of the genome (mapping it and understanding it by comparing it with different organisms) |
| sequencing the genome of an organism | -first mapped to identify location of chromosomes. information such as microsatellites (short runs of 3-4 pairs) is used -Samples of DNA is sheared away into sections of around 100 000 base pairs -placed in separate bacterial artificial chromosomes and transferred to E. coli as the cells grow many copies of the DNA is created cells containing specific BACs have their DNA cut using restriction enzymes these fragments are separated via electrophoresis fragments sequenced and then analysed by a computer |
| Comparing genomes | Comparing genomes from pathogenic and non-pathogenic organism could give hints in the production of more effective drugs. |
| electrophoresis | a gel (plate) containing agarose sugar and buffer solution with electrodes at either end. As longer strands get caught on the sugar they are separated by length. -The DNA samples are first treated with restriction enzymes -placed in negative wells immersed in tank of buffer each fragment will have a marker The DNA can be lifted for further analysis using the southern blotting technique a nylon sheet is placed over which transfers the DNA |
| DNA probes | a short single stranded piece of DNA (50-80 nucleotides long) complementary to a section of the DNA being investigated and has a label of some kind. They bind to complementary sections called annealing. Micro-arrays allow for detection of specific alleles by comparing probes |
| DNA structure | -Antiparallel backbone strand -strands have a 5' prime end and a 3' prime end -grows from 3' end -base pair ruling of A-T and C-G |
| PCR | DNA sample and DNA nucleotides heated to 95C breaking hydrogen bonds. Temperature reduced to 55C and primers anneal. Raised to 72C and DNA polymerase extends primers using free nucleotides |
| DNA polymerase enzyme | thermophillic so can survive the high heat of the PCR process obtained from a bacterium which grows in hot springs |
| interrupted PCR and electrophoresis | Primers anneal to 3' end of template strand allowing polymerase to attach. DNA nucleotides are added some are marked as there is so much genetic material by chance the chain is stopped by a marker at every nucleotide. The solution is then electrophoresised to separate the chains followed by identification of labels sequencing the DNA |
| Genectic engineering | -the required gene is obtained -copy of gene placed in vector (e.g. liposome) -vector carries gene to recipient cell -recipient expresses the gene through protein sysnthesis |
| getting the gene into the recipient cell | -Electroporation: high coltage pulse to disrupt membrane -microinjection: DNA is injected using a very fine micropipette -viral transfer: virus's mechanism -Ti plasmid inserted into soil bacterium which infects plant -Liposomes: DNA wrapped in lipid molecules. these are fat-soluble and can crooss the lipid membrane by diffusion |
| Restriction enzymes | cut through DNA at specific points. Each have a specific restriction site giving a "staggered cut" leaving a few bases exposed known as the sticky end. DNA ligase catalyses the condensation of DNA strands. During genetic engineering the desired gene is cut out using restriction enzymes and entered into the recipient cell the DNA of which cut using the same enzyme making the two complementary. EcoR1 (restriction site) |
| why genetically engineer? | 1- improving a feature e.g. inserting a gene for plant resistance to herbicides 2- organisms that can synthesis useful products e.g. production of insulin in E. coli |
| Recombinant | when DNA is removed from one organism and entered into another the new organism's DNA is described as recombinant e.g. addition of DNA into a plasmid makes it recombinant |
| Bacterial take up of plasmids | Large quantities of recombinant plasmids are mixed with bacterial cells which take up the plasmid in the process of "heat shock". Calcium salts are added and the temperature lowered to near freezing followed by quickly raising the temperature to 40C which causes the bacteria to more readily take up the plasmid. Even so only around 0.25% take up the plasmid these are described as transformed and the addition of DNA by definition means they are transgenic |
| bacterial conjugation | DNA passed between bacteria even sometimes of different species this is a major concern for antibiotic resistance as it can quickly spread and make the whole colony antibiotic resistant. |
| inserting human insulin gene into bacteria | mRNA found via centrifugation and used reverse transcriptase to synthesise a complementary DNA strand adding DNA polymerase produces a complete copy of the gene called cDNA. Plasmids are then cut open and the cDNA added and then inserted into the bacteria E. coli. |
| identifying transformed bacteria | the plasmid entered into the bacteria will have resistance to two antibiotics however, if the cDNA is successfully inserted then it will break one of the resistances. The bacteria are then placed on agar with the unbroken antibiotic resistance killing all of the bacteria who didn't pick up the plasmid. Some of these are then placed on the broken antibiotic resistance identifying which colonies have taken up the recombinant cDNA |
| vitamin A deficiency | 500 000 people each year become irreversibly blind due to a lack of vitamin A. Over 120 million people mainly in Africa and south Asia are affected in some way with around 1-2 million deaths annually. With children and pregnant women being particularly at risk. |
| Golden rice | contains beta-carotene naturally converted into vitA in the body. Goldren rice has had genes from daffodil and a bacteria inserted which cause natural precursor molecules to be converted into beta-carotene in the endosperm |
| Gene therapy | some genetic disorders could be treated via the addition of functional copies of a gene into the cells containing the dysfunctional genes the transcription of the functional gene will treat the illness. |
| somatic cell gene therapy | augmentation: where genes are added killing specific cells: cancers can be treated by eliminating certain populations of cells. |
| germline cell gene therapy | the engineering of sex cells changing the genes in all of the organisms cells capable of passing on the genes to offspring. This is illegal in humans, however, somatic gene therapy is not as it is restricted to the actual patient |
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