When is PCR useful?
When only a small amount of DNA is available eg crime scenes samples of blood, semen or tissue
What do PCR do?
It’s a way of producing large quantities of specific target sequences of DNA
What are the 3 steps of PCR?
1) denaturation- DNA sample is heated to separate into 2 strands
2) annealing- DNA primers attach to opposite ends of the target sequence
3) elongation- a heat tolerant DNA polymerase (Taq) copied the strand
One cycle of PCR results in what?
2 identical copies of DNA
What is gel electrophoresis?
A technique which is used to separate fragments of DNA according to size
How are DNA chopped on gel electrophoresis?
What is the process of gel electrophoresis?
1) samples of DNA are placed in wells of agarose Jel
2) gel is placed in buffering solution and an electrical current is passed across the gel
3) DNA, being negatively charged (due to phosphate) moves to a positive terminus (anode)
How does gel electrophoresis separate DNA according do size
Smaller fragments are less impeded by gel matrix and moves faster so fragment are separated according to size
30 cycles of PCR can result in a yield of how many copies?
How can size be calculated in gel electrophoresis?
Size can be caliualted in kilobase by comparing it against a known jndustry standard
Draw the process of gel electrophoresis
What is gel electrophoresis used for when separated into sizes?
Process of matching an unknown sample of DNA which a known sample to see if they correspond– it’s called DNA profiling
If after gel electrophoresis the pattern of bands formed by 2 samples are identical what does it mean?
If patters are similar what does it mean for the 2 individuals?
If identical= same person
If similar= related
When can DNA profiling be used
In paternity suits when the identity of someone’s biological father is needed of crime scenes collect blood etc
What can gel electrophoresis helpful in the environment
Use DNA samples taken from birds etc to see which animals are related etc
How does gel electrophoresis work in paternity testing?
Children inherit half of their alleles from each parents and thus should posses a combination of parent alleles
How does gel electrophoresis work in forensic investigation?
Suspect DNA should be a completes tvh with a sample take from a crime scene if a conviction is to occur
What is the human genome project?
Set out to sequence the complete human genome
What is a genome?
Is a catalogue of all the bases it possesses (3 billion base pairs ~25,000 genes)
What are 4 outcomes of the completed human genome project?
Mapping, screening and ancestry and medicine
The 4 outcomes mapping,screening and ancestry and medicine- explain how there useful?
Mapping; know the number,location and basic sequence of human genes
Screening: allowed for the production of specific gene probes to detect sufferers and carriers of genetic disease conditions
Ancestry: gives us improved insight into the origins,evolution and historical migratory patterns of humans
Medicine: discovery of new proteins and their function, we can develop improved treatments (pharmacogenetics, drug design)
What is gene transfer?
The technique of taking a gene out of the organism (donor organism eg fish) and placing it j to a another organism (eg tomato) made the tomato more resistant to cold
The genetic code is universal how is that useful in gene transfer?
Means every living organisms has the same codons (A,T,C,G) for the same amino acids therfore means genetic information from 1 organism can be translated by another
What is an example of gene transfer and the process?
Make human insulin
1) plasmid is remove from host
2) plasmid Is cut open using a restriction endonuclease
3) gene is pasted into plasmid using DNA ligase–> plasmid is now called a recombinant plasmid and can be used as a vector, a tools for introducing new gene into organisms genetic make up
4) finally vector is placed inside host bacterial and the bacterium is give idea conditions to grow and proliferate
Where is the bacterium put once the new vector is in it?
A bioreactor, a vat of nutritious liquid kept at a warm temperatures
The process of gene transfer has allowed e.coli do successfully do what?
Make human insuline
Why is it better to use gene transfer for insulin rather than from pigs or cow carcasses?
Causes allergy problems and the other way foesnt
What are 2 examples of current uses for modified crops?
1) engineering crops to extend shelf life of fresh produce
2) engineering crops to protect itself from insects
Give an example of an engineered crop to extend shelf life
Tomatoes (flavr savr) hve been engineered to have an extended keeping quality by switching off the gene for ripening and thus delaying the natural process of softening fruit
Give example of engineering crops to protect insects
Maze crops (Bt corn) have been engineered to be toxic to the corn borer by introducing a toxin gene from a bacterium (bacillus thurgrienis)
Give 2 examples of uses today of genetically modified animals
1) engineering animals to enhance protein
2) engineering animals to produce desired products
Give example of engineering animals to enhAnce protein
Sheep produce more woll when engineered with the gene enzyme responsible for the production of cysteine- main amino acid in the keratin protein of wool
Give example of engineering animals to produce desired products
Sheep engineered to produce human alpha- 1- antitryspin in their milk can be used to help treat individuals suffering from hereditary emphysema
What are potential benefits of Gentic modification?
1) GM crops will help farmers by improving food production
2) crops will produce there own pest- control which means fewer chemical pesticides w be used
3) used GMO’s to produce rare proteins for medication or vaccines could be less costly and produce less pollution that synthesising such proteins in labs
4) farmers have more control over what they crop or livestock
5) may help reduce hunger in developing nations by using pest resistance crops or GM plants which require less water
What are the harmful effects of using genetic modification?
1) no one knows long term effects on wild
2) could change food chain/habitation
3) cod cause gene cross species– no one knows consequences
4) Bt crops which produce toxins could be harmful to humans
5) risk of allergy
6) decrease in biodiversity
Group of genetically identical organisms or a group of cells artificially derived from a single cell
Draw a diagram for cloning using different animal cells
What is the 7 step process for cloning?
1) somatic cell (non gamete cell) from udder was collected and cultures as nucleus removed
2) unfertilised egg collected from another sheep - nucleus removed
3) using a zap of electrical current, egg cell and nucleus from cultures somatic cell are fused together
4) new cell developed in vitro on similar way to zygote and started to form embryo
5) embryo place d in womb of surrogate mother sheep
6) embroil developed normaly
7) dolly was born
What is therapeutic cloning?
Aim is to develop cells which haven’t gone through process of differentiation, cells are referred to as embryonic stem cells
What can therapeutic stem cells do?
- make transplantable plants
- replace damaged tissues
What are arguments for therapeutic cloning in humans?
- can grow skin to repair serious burns
- grows new heart muscle to repair ailing heart
- grow new kidney tissue to repair failing kidney
- can be used to cure serious diseases with cell therapy
What are the arguments against therapeutic cloning in humans?
- involves creation and destruction of human embryos
- capable of continued divions– causing cancerous cells and cause tumours
- more embryos produced than needed, excess are killed