The importance of microbes and how they can affect the lives of humans and other organisms

Question 1

pathogens: The importance of microbes and how they can affect the lives of humans and other organisms

Answer 1

• Pathogens
• Nitrogen cycle
• Eutrophication
• Use of bacterial enzymes in DNA technologies

Question 2

pathogens: The importance of microbes and how they can affect the lives of humans and other organisms

Answer 2

• Microbes consist of prokaryotic organisms such as bacteria and viruses. Pathogens do have a negative effect on the lives of organisms as they can invade tissues and cause symptoms of sickness, however they are important in stimulating the primary immune response that produces memory cells against the pathogen.
• Firstly, the pathogen is recognised as foreign in the body by a phagocyte, which then engulfs the pathogen via phagocytosis, containing it in a phagocytotic vacuole which fuses with lysosomes to release lysozymes which digest the antigens of the pathogen.
• Phagocytes than active T-cells which bind to the complementary antigen presented by phagocytes to stimulate B cells.
• B-cells bind to the complementary antigen and become activated by clonal selection to divide into plasma cells that secrete antibodies that cause the pathogens to agglutinate together to increase the rate of phagocytosis.
• The B and T cells involved in the primary response produce memory cells with complementary shapes to the antigens of the pathogen, so when the pathogen re-infects they are able to recognise the antigens and bind to them to trigger an immune system response at a faster rate than before preventing any symptoms caused by the pathogen.
• Memory cells triggered by the pathogen are extremely significant, and led to the development of vaccines that inject a dead/inactive pathogen to stimulate the production of memory cells so that our immune system is able to immediately respond when it is invaded by a pathogen.
• For example, if not for the outbreak of the smallpox virus scientists would be unable to develop successful vaccines against further harmful microbes such as the corona virus, potentially saving the lives of thousands of people.
• Therefore, microbes play a significant role in leading to advancements in the human immune system by technology.

Question 3

nitrogen cycle: The importance of microbes and how they can affect the lives of humans and other organisms

Answer 3

• Microbes are significant in maintaining nutrient cycles such as the nitrogen cycle which allows plants to synthesise chlorophyll.
• Firstly, via nitrogen fixation mutualistic nitrogen-fixing bacteria use the enzyme nitrogenous to reduce gaseous nitrogen into ammonia.
• Secondly, saprobionts feed on and decompose organic waste containing nitrogen to release NH3 gas which dissolves in water soil to form ammonium ions.
• Thirdly, anaerobic denitrifying bacteria convert soil nitrates back into gaseous nitrogen, and the cycle continues again by nitrogen-fixing bacteria.
• This is an essential cycle supported by microbes such as nitrogen fixing bacteria and saprobionts, due to the fact that plants require nitrogen in order to synthesise chlorophyll, which absorbs light energy for photosynthesis.
• Without chlorophyll, the plant would be unable to photosynthesise to produce glucose which is contained in their cell membranes as cellulose.
• Therefore, the plant cell walls would be unsupported due to lack of cellulose and unable to withstand turgor pressure, turning them flaccid.
• In conclusion, microbes have a significant role in the nitrogen cycle which supplies plant cells with nitrogen so that they can synthesise chlorophyll for photosynthesis.

Question 4

eutrophication: The importance of microbes and how they can affect the lives of humans and other organisms

Answer 4

• Microbes play a significant role in the process of eutrophication, which negatively impacts ecosystems of organisms living in bodies of water.
• Eutrophication occurs due to the leeching of fertiliser into bodies of water, causing aquatic plants to grow exponentially since nitrate level is no longer a limiting factor.
• Algal bloom on water surface prevents light from reaching the bottom and plants die.
• Oxygen levels decrease as population of aerobic saporbionts increase to decay the dead matter, so fish die.
• Anaerobic organisms reproduce exponentially and produce toxic waste which makes water putrid.
• Eutrophication negatively impacts ecosystems by decreasing biodiversity due to a various number of species of fish and plants dying in the putrid water.
• Moreover, if this occurs in freshwater lakes where water is sourced from it may cause tainted drinking water supplies - thus making our water undrinkable which also affects humans.
• Therefore, microbes negatively impact the lives of humans, plans and animals via eutrophication.

Question 5

recombinant DNA: The importance of microbes and how they can affect the lives of humans and other organisms

Answer 5

• Microbes are significant in recombinant DNA technologies as they are used to transfer one organisms DNA into another’s via vectors.
• Firstly, restriction endonucleases cut DNA at restriction sites, to allow the target gene to be cut out of the DNA strand leaving sticky ends.
• A plasmid extracted from a microbe (bacteria) is also cut using the same restriction enzymes as the DNA so that the sticky ends are complementary to each other allowing DNA ligase to join the DNA fragment and plasmid together by reforming phosphodiester bonds forming the recombinant DNA.
• The vector containing recombinant DNA is then inserted into a host cell by mixing the vectors in an ice cold solution of calcium chloride, and heat shocking the cells to encourage them to take up the vectors by increasing the permeability of their cell walls.
• The cells can then be grown and the DNA fragment will be cloned. The use of plasmids in recombinant DNA gives advantages to agriculture as it allows them to genetically engineer crops to have a higher yield and productivity by: being resistant to herbicides, resistant to pests and enriched in certain vitamins to increase their nutritional value.
• Therefore, microbes positively impact humans as well as animals by allowing us to genetically engineer plants that have a higher crop yield and nutritional value than plants grown naturally.