Biochemistry and the environment

Nature of science:

Risk assessment, collaboration, ethical considerations—it is the responsibility of scientists to consider the ways in which products of their research and findings negatively impact the environment, and to find ways to counter this. For example, the use of enzymes in biological detergents and to break up oil spills, and green chemistry in general. (4.8)

• Xenobiotics refer to chemicals that are found in an organism that are not normally present there.
• Biodegradable/compostable plastics can be consumed or broken down by bacteria or other living organisms.
• Host–guest chemistry involves the creation of synthetic host molecules that mimic some of the actions performed by enzymes in cells, by selectively binding to specific guest species, such as toxic materials in the environment.
• Enzymes have been developed to help in the breakdown of oil spills and other industrial wastes.
• Enzymes in biological detergents can improve energy efficiency by enabling effective cleaning at lower temperatures.
• Biomagnification is the increase in concentration of a substance in a food chain.
• Green chemistry, also called sustainable chemistry, is an approach to chemical research and engineering that seeks to minimize the production and release to the environment of hazardous substances.

Applications and skills:

• Discussion of the increasing problem of xenobiotics such as antibiotics in sewage treatment plants.
• Description of the role of starch in biodegradable plastics
• Application of host–guest chemistry to the removal of a specific pollutant in the environment.
• Description of an example of biomagnification, including the chemical source of the substance. Examples could include heavy metals or pesticides.
• Discussion of the challenges and criteria in assessing the “greenness” of a substance used in biochemical research, including the atom economy.

.

• The term green chemistry was first coined in 1991, and acceptance of its philosophy has led to developments in education and legislation in many countries.
• Use of the pesticide DDT is banned in most countries due to its toxic effects and biomagnification. Its use continues, however, in countries where malaria remains a major public health challenge.

Utilization:

• Syllabus and cross-curricular links:
• Topic 4.4—intermolecular forces
• Topic 10.1—natural and synthetic organic compounds
• Options A.5 and A.7—environmental impact of plastics
• Option D.2—antibiotics

Aims:

• Aim 6: Experiments could include the comparison of the breakdown of biodegradable and non-biodegradable plastics in the environment.
• Aim 6: Risk assessment, including the risks to the environment, is an essential part of all experimental work.
• Aim 8: The development of the science of green chemistry has raised awareness of the environmental and ethical implications of using science and technology.

• Specific names of “green chemicals” such as solvents are not expected.
• The emphasis in explanations of host–guest chemistry should be on non- covalent bonding within the supramolecule.