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Biology U4AOS2 - Coggle Diagram
Biology U4AOS2
Genetically Modified Organisms (GMOs)
Plant examples
Insect resistance, herbicide tolerance, virus resistance, delayed resistance, tolerance to environmental stress (drought, food, salt), enhanced nutritional value, improved post-harvest shelf life
Animal examples
Growth hormone (+promotor and terminator sequences), Follicle-Stimulating Hormone (FSH), human proteins
Transgenic Organism (TGO)
subgroup of GMO including genetic material from another unrelated species
Biological Implications
Pros: better crop productivity, insect-resistant GM plants require less pesticides, improved nutritional content
Cons: lose effectiveness if weeds/pests evolve resistance, loss of genetic diversity, cross-pollination between GM crops may cause gene spread
Can be achieved by addition or silence of a gene/DNA segment
Social Implications
Pros: increase crop productivity, grow in more adverse conditions, herbicide tolerant (less labour), increased crop yield, improved flavour, texture or nutritional content
Cons: New seeds can be expensive, complex legal issues can cause stress
New combinations of genes are created that are not seen in natural populations
Ethical Implications
Pros: not using this technology is wrong
Cons: GMOS are unnatural (playing God), believe they are unsafe to eat, can be seen as inhumane
Organisms whose genome has been altered using genetic engineering technology
Emergence of new diseases
Approaches needed to combat a new disease
Prevention (sanitation), surveillance, quarantine and isolation, identification of the pathogen, identify and control method of spread, treatment
Zoonosis
disease that is transmitted to humans from animals
Epidemic
widespread occurrence of an infectious disease in a community or in a restricted geographic area at a particular time
Antigenic Drift
gradual small changes to a virus by single point mutations that encode surface protein markers
Pandemic
global outbreak/spread of a disease that affects a high proportion of the population
Antigenic Shift
sudden big change, process of re-assortment of RNA segments from two (or more) different virus subtypes in a single host
Gel Electrophoresis
An electric current is used to seperate fragments based of their differing lengths
Shorter fragments travel further than longer fragments
DNA is negatively charged and fragments can be of different lengths
Using a standard means to use a DNA fragment of a known length (used to compare other results against)
Steps:
1) Collect DNA (perhaps through PCR)
2) Fill the electrophoresis chamber with buffer solution
3) Fill the wells with DNA samples
4) Apply an electric current to the chamber and wait for the samples to separate
5) Interpret the banding pattern of the DNA fragments by comparing to a standard
Gene Cloning
Advantages
high levels of purity, reliability of supply and consistency of quality between batches
Steps
Insert gene of interest into plasmid
Transfer plasmid to host cells
Identify host cells with recombinant plasmid
Culture recombinant cells or mass culture
Isolate and purify
Recombinant DNA
DNA that is formed by combining DNA from different sources, often from different kinds of organisms
Social and ethical implications
Reduced impact on animals (via testing)
Reduced pressure on hospitals
Needs tight regulations and equity of access
Privacy and confidentiality issues
Process by which a gene of interest is located and cloned to produce multiple copies
Recombinant Plasmids
This new genetic information provides the organism with a new trait which is identifiable after transformation
Fragments of DNA are joined together by the enzyme DNA ligase, producing a molecule of recombinant DNA
Genetic transformation occurs when a cell takes up (takes inside) and expresses a new piece of genetic material (DNA)
Generally the success rate of transferring recombinant plasmids into bacterial cells is low, but it can be increased though electroporation (electric shocked to create holes in plasma membrane so plasmid can enter easier) or heat shock (moved from ice bath into 42 degree water bath, increases fluidity of plasma membrane, increases the chance of uptake of plasmids
Use of enzymes
Ligase
Ligation
sticking back together DNA fragments
Annealing
coming together of base pairs
Joins double stranded DNA pieces together
Polymerase
Joins nucleotides together to extend the strand
Catalyses the addition of bases. E.g. DNA polymerase is the primary enzyme which catalyses the linking of the 3' hydroxyl group of the end nucleotide and the 5' phosphate of the nucleotide to be added
Endonuclease (restriction enzyme)
They recognise a specific DNA sequence, called a restriction site, and cleave the DNA within or adjacent to that site
Some leave sticky ends and others blunt ends
Polymerase Chain Reaction (PCR)
Making multiple copies of a specific section of DNA for a range of purposes
Steps
1) Denature: separate the two strands of DNA -> 95 degrees
2) Bind primers: annealing -> 50-60 degrees
3) Extend primers: free nucleotides are added to the DNA to create new, identical DNA -> 72 degrees
Taq polymerase
Used as it can withstand the high temperatures need to seperate the DNA strands
It's optimum temperature is 75-80 degrees and can replicate a 100 base pair strand of DNA in less than 10 seconds at 72 degrees
DNA Manipulation
Involves the direct manipulation of an organism's genome using biotechnology
Genetically Modified Organisms (GMOs)
Created in the following processes: adding a gene, altering a gene, deleting or 'turning off' a gene