3.5 Genetic modifications Flashcards
Explain PCR
PCR: multiply the copies of a desired DNA fragment by artificial replication
- Dentauration
- Annealing
- Elongation
Explain gel electrophoresis
Gel electrophoresis allows to sepratae proteins/DNA fragments depending on their mass/size
- Samples are prepared to carry charge: proteins in appropriate buffers, DNA negative, stained - placed in gel
- Electric current is applied - causes samples move trhough gel - largets move the least, smallest - the most
- Using a mixture of known mass fragments - determine the mass of samples
Explain DNA profiling
DNA profile is unique - non-coding satellite DNA STR - PCR - gel electrophoresis - compare
- paternity tests
- forensic investigations
Explain gene trasnfer
DNA - universal code - organism can express foreign genes if incorporated
Transfer of genes between species - genetic modification - organism - transgenic (ex bacteria producing human insulin)
Steps:
- gene and vector isolated nad multiplied - centrifugation - PCR
- restriction endonucleases cutting needed places in gene and vector - create sticky ends for inserting
- gene incorporated into vector by DNA ligase - fuse sugar-phosphate backbones - recombinant construct
- vector trasnfer into organism
- selecting the successful transgenic organisms - antibiotics - purification of expressed gene - protein
Sticky ends vs blunt ends
When restriction endonucleases cut vectors and DNA samples - in cloning leave sticky ends - more safe gene insertion into vector
Benefits vs risks of GMOs
Example of GMO in rela life and problems with it
Bt corn is GMO - incorporated insecticide gene - better harvest BUT harm monarch butterflies - pollen from Bt corn transferred to milkweeds - butterfly larvae feed - lower chances of survival BUT another study found no relationship
Define clones
CLONES: a group of organisms which are genetically identical (asexually produce clones, sexually - rarely but identical twins)
Explain somatic cell nuclear transfer
INn somatic cell nuclear transfer cloned embryos can be produced using differentiated adult cells
- somatic adult cells taken - cultured
- nucleus of unfertilised egg destroyed with UV - removed - enucleated egg cell - nucleus from somatic cell replaced
- electric current applied to stimulate division - development into embryo - implanted into uterus
Sheep Dolly
Natural cloning methods
- Binary fission
- Budding (yeast)
- Fragmentation (new oegnaisms grwo from separated fragments of parent organisms - starfish)
- Parthenogenesis (embryos form from unfertilised egg (diploid by female - insects, fish, reptiles)
Explain method for plant cloning
Vegetative propagation - ability to grow seprate organisms independently from a piece of another organism (plant roots, shoots)
- strawberries form runners
- micropropagation
Human cloning methods
If the zygote randomly splits into two - monozygotic twins (share 100%)
or
If egg cell divides before fertilisation - dizygotic - on-identical twins (share 50%)
Reproductive vs therapeutic cloning
Explain cloning via embryonic division
- embryos separated while still pluripotent - form cloned organisms - implanted into uterus - grow to form several fetuses
Problem: the orginal embryo is formed in sexual reproduction - genetics not controlled but can produce identical organisms
Explain stem cutting
Stem cutting: separated portion of a plant stem which can regrow into an independent clone
- all stems possess nodes - meristem cells - planted in soil with upper nodes out - new plant propagated (roses, grapes)
Factors that influence success:
- position of cutting
- growth medium
- conc of growth hormones
- growth conditions (temperature, sun, water, pH)
Explain micropropagation
