Cloning

A clone is a group of genetically identical organisms or a group of cells derived from a single parent cell.

Separated into reproductive cloning and therapeutic cloning.

Therapeutic cloning involves the isolation of stem cells (can be adult e.g. bone marrow or foetal – i.e. from an embryo/foetus)

Foetal stem cells are often harvested from unused IVF embryos.

These have the potential to be of great medical benefit. E.g. healing burns, heart tissue post cardiac arrest, kidney damage.

1.     Discuss the ethical arguments for and against the cloning of humans (4)

Arguments against cloning:

·      Reduces the value or dignity of an individual and may cause psychological problems

·      High miscarriage rates

·      Cloned individual are likely to have development disorders or health problems

·      Cloned individuals may show premature aging

·      Costly process and money could be better spent on other forms of healthcare

·      Cloning may be carried out for inappropriate motives e.g. to replace lost loved ones or achieve a perfect race

Arguments for cloning:

·      Identical twins are formed by cloning so it could be argued that it’s a natural process

·      Cloned embryos can be tested for genetic diseases (genetic screening)

·      Increased change of children for infertile couples

·      Cloning research may lead to spin-offs for other research areas such as cancer (transplant research or regeneration research)

2.     Outline a basic technique for gene transfer involving plasmids (5)

a.     Messenger RNA coded for insulin is extracted from human pancreas cells

b.     DNA copies of the messenger RNA coding for insulin are made using the enzyme reverse transcriptase

c.     Plasmids are small loops od DNA found in bacteria. They are cut open using the restriction enzyme endonucleouse

d.     The insulin gene and plasmid are mixed

e.     DNA ligase seals up the plasmid

f.      The plasmid with the human insulin gene is inserted into a recombinant plasmid

g.     The recombinant plasmid are mixed with a strain of E. Coli bacteria

h.     The E. Coli bacteria starts to make insulin which is then extracted, purified and used by patients suffering from diabetes

3.     Outline a technique for transferring genes between species (5)

a.    The gene of interesting is cut out with a restriction enzyme

b.    RNA is used to produce DNA using reverse transcriptase

c.     The plasmid is cut open with the same restriction enzyme

d.    The gene is inserted into the plasmid by the blunt/sticky ends

e.    They are spliced together by DNA ligase

f.      The recombinant plasmids are cloned and many copies are produced

g.     Recombinant plasmids are inserted into new host cells, could be a virus, bacteriophage or yeast. This insert is done by shooting/spraying/microencapsulating by heat treatment

4.4.1              Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA.

Polymerase Chain Reaction (PCR)

PCR is a laboratory technique which takes a very small quantity of DNA and copies all the nucleic acids in it to make millions of copies of the DNA. PCR is used to solve a very simple problem: how to get enough DNA to be able to analyze it.

When collecting DNA from the scene of a crime or from a cheek smear, often only a very limited number of cells are available. By using PCR, forensics experts or research technicians can obtain millions of copies of the DNA in just a few hours. Such quantities are large enough to get results from, notably using gel electrophoresis. 

Bioengineering

Bioengineering is the transfer of genes between species.

The genetic code is universal – this means that in any species so far identified, the same codons code for the same amino acids.

4.4.10            Discuss the potential benefits and possible harmful effects of on example of genetic modification.

Benefits

• ·       GM crops help farmers by improving food production
• ·       GM crops which produce their own pest-control substances are beneficial to the environment because fewer chemical pesticides will be needed
• ·       Using GMOs to produce rare proteins for medication or vaccines could be less costly and produce less pollution than synthesizing these proteins in laboratories
• ·       Farmers can be in more control of what crops or livestock they produce
• ·       The multinational companies who make GM plants claim they’ll enable farmers in developing nations to help reduce hunger by using pest-resistant crops or GM plants which require less water

Harmful Effects

• ·       The long term effects of GMOs in the wild are unknown. Efforts to keep GM plants under control in well-defined areas have failed and pollen from GM crops have escaped to neighbouring fields. Genes from GM plants could be integrated into wild species, giving them un unnatural advantage over other species and an ability to take over the habitat
• ·       There is a danger that the genes could cross species. It has been proven possible in laboratories, so it’s possible in nature too. Again, no one knows the consequences of genes crossing species
• ·       Crops which produce toxins to kill insects could be harmful to humans because, unlike chemical pesticides which are only applied to the outer surface, the toxins are found throughout the plant
• ·       There are risks for allergies. E.g. if someone is not allergic to natural tomatoes but is allergic to GM tomatoes, they will need to know which one they’re eating. But there is no difference in the outward appearance of the fruit and food labeling is not always clear
• ·       There are worries that large portions of the human food supply will be the property of a small number of corporations
• ·       High-tech solutions are not necessarily better than simpler solutions. Crop production could be increased by teaching farmers how to use water and natural pest-control systems more efficiently
• ·       A proliferation of genetically modified organisms may lead to a decrease in biodiversity