NESA Biology Biotechnology

A plant biotechnology that is of benefit to society is recombinant DNA technology eg when used to produce Bt corn or Bt cotton.

Recombinant DNA technology has many ethical implications. For example, Bt corn seeds cost money to purchase each season, while farmers using normal corn seeds can regrow their crops each year from their own seeds. This leads to inequalities in who has access to these GM seeds, and thus access to markets to sell their products.

The use of selective breeding/hybridisation is a type of biotechnology used in animals eg hybridisation of dairy cows to produce greater milk yielding cows. This has ethical implications for example, the side-effect of continuously selecting for greater milk yield has been a decrease in fertility amongst these cows, and may affect quality of life for cows.

However, there are also many benefits to society of the use of recombinant DNA technology or selective breeding/hybridisation. For example:

• the production of more food like Bt corn which can allow the human population to continue to grow, or greater milk availability for consumers in society
• greater yields for farmers, leading to increased profits and quality of life for farmers.

To produce the genetically modified (GM) mosquitoes, it is necessary to transfer the SERPINE 1 gene from a human to the mosquito using recombinant DNA technology. Restriction enzymes are used to cut the SERPINE 1 gene from a human cell chromosome. A bacterial plasmid (circular DNA) is opened using the same restriction enzymes and the SERPINE 1 gene is inserted and attached using DNA ligase. The bacteria then reproduce, producing multiple copies of the SERPINE 1 gene. The gene can then be delivered into the mosquitos. This can be done by micro-injection into mosquito egg cells, so that the mosquito which develop from the egg will contain the SERPINE 1 gene, which will allow the mosquito to express PAI-1.

In recombinant DNA technology, selected genes can be cut and pasted from one organism into another using, for example, ligase enzymes. The human insulin producing gene has been transferred into bacteria, allowing for increased production of insulin, benefitting sufferers of diabetes, who can access insulin more readily and cheaply. This means that diabetes patients have a greater life span.

Genetic technologies such as CRISPR can be used for controlling pest populations including insects that cause diseases in both humans and other animals. By controlling the number of disease causing insects eg mosquitoes that cause dengue fever, we can significantly reduce the incidence of the vector-borne diseases. This would result in healthier populations and reduced stress on the health care system.

These technologies have largely been beneficial to society, improving access to drugs, the life expectancy and quality of life for many people.

To genetically modify bacteria using recombinant DNA technology, first isolate a suitable gene, which must be a gene that produces an enzyme that digests oil. Choose a suitable bacterium for genetic modification (one that can survive in aquatic environments). Use the same restriction enzyme to remove the gene from the host and insert it into a plasmid. Amplify the target gene in the plasmid or by polymerase chain reaction (PCR), and insert the gene into the target bacteria. Transform the bacteria using heat shock, and check the ability of the bacteria to reproduce and produce the gene product.

The advantages of this use include the ability to use genes from other species to achieve outcomes not possible via natural processes. After development, it is easy and fast to produce and supply transgenics in large quantities; and microorganisms are easy to transport, handle, and store.

However, disadvantages include that transgenic organisms could have a negative impact on other organisms or the environment, such as oil-digesting bacteria taking over and displacing natural bacteria. There is also the risk of gene transfer to other organisms.

A mutation is a permanent change to DNA that occurs at random. It changes one allele to another or creates new alleles.

The significance of changes made by mutation is that they can have deleterious effects on individuals. Mutations have a limited effect on allele frequencies because the rate of mutation is low, but they are the source of all genetic variation, alleles, and biological diversity. Other evolutionary processes are dependent on this variation, and populations cannot evolve without genetic variation.

Genetic drift involves the random death of individuals, leading to random or chance changes in allele frequencies. It has the biggest effect in small populations.

The significance of changes made by genetic drift is that it can result in the loss of advantageous alleles. This places populations at risk of extinction due to an inability to adapt.