| What is gel electrophoresis used for? | to separate proteins / DNA fragments according to size (smaller fragements travel faster) |
| what is the general process of gel electrophoresis? (2) | samples travel from anode (negative) to cathode (positive) bec of electric current in a gel block |
| How are DNA fragments separated? (2) | cut into fragments w restriction endonuclease
separates bec DNA is negatively charged from PO4 3- on nucleotides |
| how can specific sequences be found with gel electrophoresis? (2) | with radiolabelled hybridisation probe
seen with autoradiography |
| Why is gel electrophoresis used to separate protein fragments different? | because protein is folded into many shapes = affects size |
| What is used to straighten protein? | Anionic SDS detergent |
| what are the steps of gel electrophoresis for proteins? (3) | 1) electric charge separates protein according to size
2) protein transferred to solid membrane
3) proteins stained w specific antibodies |
| How does gene transfer in bacteria work for producing insulin? (3) | 1) human insulin cell and bacteria plasmid combined to make recombinant plasmit
2) inserted into bacteria = transgenic
3) grown and insulin is extracted |
| what are the 4 steps in bacterial gene transfer? (I dont like salt) | isolation: with PCR
digestion: of gene and vector w restriction endonuclease
ligation: of gene and vector with DNA ligase
selection: and expression of transgenic DNA |
| what happens during isolation of gene in bacterial transfer? (3) (PCR) | centrifugation = heavier parts like nuclei are separated
specific gene needed is increased with PCR
gene sequences made with mRNA (Reverse transcriptase) to form CDNA (no introns) |
| what are vectors? | DNA molecule used to carry gene into a foregin cell |
| What happens during digestion in gene bacterial transfer? | gene and vector cut w 2 restriction enzymes at recognition sites = blunt + sticky ends |
| why is digestion done with 2 different endonucleases in gene transfer? (2) | ensures correct orientation
prevents reannealing |
| what happens during ligation of gene transfer? (2) | gene inserted into plasmid w complementary bse pairing
spliced w/ DNA ligase to join backbones with covalent bond |
| What happens during selection and expression of gene transfer? | recombinant inserted into cell to form a transgenic bacteria and expresses new protein for use |
| what are GMOS used for? | used to improve crop yields and reduce farming costs |
| what are the advantages of using GMOS? (4) | improves nutritonal standards by using genes for protein and vitamin
can grow in a range of environments (higher yield)
less deforestation and farming costs
spoils slower |
| What are the disadvantages of using GMOS? (4) | health issues like allergies
cross pollination with weeds
competes with native plants
less biodiversity |
| what is an example of a GMO used? | Bt crops |
| what are Bt crops and what are they used for? | insecticide gene from Bacillus thuringienesis which are lethal to larvae |
| disadvantage of using Bt crops? | can affect monarch butterflies because the pollen can dust milkweeds (butterfly babies feed on it) |
| weaknesses of studies conducted on the effect of bt crops on butterflies? (2) | unnatural amounts of Bt pollen used because naturally rain prevents buildup of pollen
larvae had a restricted diet |
| What are clones? | genetically identical organisms from a single parent cell |
| what is PCR? what is it used for? what are the 3 steps? temperatures used? (5) | polymerase chain reaction = amplifies DNA
1) denaturation = separate 2 strands (95)
2) annealing = primers attached to 3' end and cooled (55)
3) elongation = taq polymerase binds to primer (72) |
| what is the difference in splitting for mono and di twins in the uterus? | mono= when a fertilised egg splits
di = unfertilised egg splits and is fertilised with different sperm |
| what happens in embryo cloning? how is it possible? weakness? (3) | embryo is broken up when it is a morula and implant the different pieces in different surrogates to form identical clones
possible because they can still divide into more cells (pluripotency)
weakness: embryo is still randomly formed due to sexual reproduction and features cant be determined |
| what is a better alternative to embryo cloning and why? (2) | somatic cell nuclear transfer (Adult cloning)
more reliable method because it is known what traits will develop |
| What is the process of SCNT? (adult nucleus) (5) | 1) Somatic cells removes and cultured
2) unfertilised egg removed and haploid nucleus removed from it
3)adult nucleus added to egg to form a diploid egg
4) electric current causes egg to divide to form embryo
5) implanted into surrogate to form clone |
| what is SCNT used for? (2) | reproductive cloning
therapeutic cloning (treatment) |
| which organisms can clone? (4) | bacteria, fungi , protists
plants can through vegetative propagation |
| what are different methods of animal cloning? who does them? (4) | binary fission: elongates and splits into two = bacteria, protists (amoeba) and flatworms
budding: forms a branch and splits off = yeast
fragmentation: a part of the donor breaks of and forms a new organism (Starfish and worms)
parthenogenesis: unfertilised ova forms embryo without sperm = insect, fish, amphibians and reptiles |
| What is a method of plant cloning? | vegetative propagation = small pieces of meristem tissue are grown independently that can differentiate |
| example of vegetative propagation? (3) | garlic and onion bulbs
potato tubers
runners (horizontal) |
| What can reproduce asexually with spores? (3) | algae, mosses and ferns |
| what are stem cuttings and how are they used? (3) | part of the stem with nodes that can grow into the root, leaf or branch
quickly grows plants
Eg: sugar canes, grapes, roses |
| factors affecting stem cutting? (4) | cutting position
length
concentration of growth hormone used
temperature |
| what is satellite DNA used for and why? (3) | satellite DNA are short tandem repeats (STR) = used for dna profiling
bec people have different number of repeats
can be used for forensics and paternity issues |
| what is the process of DNA profiling? (4) | 1) DNA sample amplified with PCR
2) Satellite dna cut w restriction enzymes
3) fragments differ in size bec of diff STR lengths
4) separated with gel electrophoresis |
| how is DNA profiling used in paternity? | childs profile will be a combo of both parents and all fragments should be present in either the mom or dad |
