Microbiology Part 4 (2.4)

Question 1

What happens in the global nitrogen cycle?

Answer 1

• microbial nitrogen fixation = responsible for providing majority of the nitrogen in the biosphere
• nitrogenase enzyme converts N2 into ammonium
• nitrifying bacteria reduce ammonium into nitrites then nitrates
• plants take up these compounds form soil
• denitrifying bacteria use nitrates as an energy source + produce N2

Question 2

What happens in the global carbon cycle?

Answer 2

• methanogenic archaea release CH4 - potent greenhouse gas
• decomposers recycle carbon from dead organisms, enabling it to re-enter the food chain
• photosynthetic microbes in the ocean fix more CO2 than all the plants on land
• viruses in the ocean play an important role in recycling carbon by killing marine microbes

Question 3

What is a microbiome?

Answer 3

• host - associated community of commensal, mutualistic & pathogenic microorganisms

Question 4

Give some examples of how infectious diseases are spread.

Answer 4

• direct contact
• sexual contact
• airborne
• water/food-borne
• vector borne
• immune invasion
• replication & dissemination
• pathology & symptoms
• diagnosis e.g. culture -based, molecular
• treatments e.g. antibotics
• prevention e.g. sanitation, vaccines.

Question 5

How does climate change affect how infectious diseases are spread?

Answer 5

• Vectors - e.g. mosquitoes, carriers that come around in certain weather, and conditions.

Question 6

How does penicillin work as a antibiotic?

Answer 6

• it is a natural product synthesised by the mould penicillium
• a B-lactam antibiotic, inhibiting bacterial enzymes that form cross - links in peptidoglycan

Question 7

What are some alternatives to antibiotics?

Answer 7

• phage therapy - using bacteriophages to treat human infections
• metal ion antimicrobials - e.g. silver, in a range of medical products.

Question 8

Facts about Microbes in Food production:

Answer 8

• used to make fermented foods, e.g. kimchi and yoghurt.
• causes food spollage
• cause food poisoning e.g. bacillus cereus

Question 9

What are bacteriophages used for?

Answer 9

• to increase food security by reducing bacterial diseases of crop plants and livestock.

Question 10

What can biofertillser be used for?

Answer 10

• applying nitrogen-fixing bacteria to soils as a biofertillser

Question 11

What can baculoviruses (insect pathogens) be used for?

Answer 11

• to control insect pests + reduce crop losses.

Question 12

How are biofuels useful in today’s society?

Answer 12

• algae used to make biofuels, bioethanol, biodiesel

- a promising alternative to fossil fuels.

Question 13

How is bioremediation useful in today’s society?

Answer 13

• microbes (metabolic diversity) used to clean up pollution. e. g. crude oil
• looking for microbes that degrade plastic

Question 14

What are restriction endonucleases?

Answer 14

• enzymes produced by bacteria to defend themselves against bacteriophages
• cut DNA at specific sites + widely used in molecular cloning techniques.