Micro-Organisms in Ecosystems

1. Micro-Organisms in Ecosystems

2. Many micro-organisms get their nutrients from symbiotic relationships with other organisms. • There are three types of symbiotic relationships:

3. 1. Parasitism • This is where one member of the relationship benefits (the parasite) and the other is harmed (the host). • The parasite usually only takes what it needs to survive, because if the host dies then so will the parasite • All micro-organisms that cause disease (including viruses) are parasites • Categorized as +/- relationship

4. e.g. Streptococcus • Digests sugar in your mouth, but produces lactic acid that destroys tooth enamel

5. 2. Commensalism • One member of the relationship benefits (the commensal) while the other is neither harmed nor helped (the host) • Many bacteria live in the intestines of mammals • Categorized as a +/0 relationship

6. E.g. Corynebacterium • Lives on the surface of the human eye, eating secretions and dead cells.

7. 3. Mutualism • Each member of the relationship is dependent on the other. • Neither member can complete its life cycle alone • Categorized as a +/+ relationship • Lichens and mycorrhizae are mutualisticrealtionships

8. E.g. Rhizobium • Is a bacteria that lives in the roots of plants • It provides the plant with N (for protein) and the plant provides the bacteria with sugar

9. Micro-organisms & Biotechnology • Biotechnology is the use of living organisms for commercial applications • Before the term biotechnology was coined people had been creating it for centuries: • Using bacteria to produce cheese and yogurt • Fermenting plant matter to create silage (cattle feed) • Tree bark chewed to relieve headaches

10. Modern biotechnology involves genetic engineering • Used to insert DNA from other organisms in to bacteria • Used to create many products that are useful (and necessary) to humans • Insulin • Growth hormone • Blood factors for hemophiliacs • Some vaccines • Interferons to treat cancer 1. Recombinant DNA

11. Also used to improve plant crops • Resist pests • Improve taste • More nutrients • Longer shelf-life

12. Using Recombinant DNA to Produce Human Insulin Copy Diagram into notes!

13. This method takes advantage of the virus’ attack plan • Recall that they ingest their DNA into the host cell to “hijack” it. • Only works with cells that are dividing • Will not work with brain and spinal cord cells 2. Viral Vectors

14. Using a Viral Vector to Insert a Gene in A Lymphocyte