Lecture 131. Rank the macroelements in abundance in the cell a. C: 50%b. O: 17%c. N: 13%d. P: 2.5%e. S: 1.8%f. Se: <.01%2. Compare and contrast macro- and micro-elements a. Micro- 5% of dry cell weightb. Macro- 95% of dry cell weighti. Stabilize ribosomes membrane and enzyme activity 3. Define what a limiting nutrient isa. Nutrient that runs out the fastest4. Rank the macromolecules based on abundance in the cell a. Protein: 55%b. RNA: 20.5%c. Lipid: 9.1%d. Polysaccharide: 5%e. Lipopolysaccharide: 3.4%f. DNA: 3.1%5. Recall what fastidious organisms are a. Cannot grow in absence of growth factors6. Define what growth factors are a. Organic compounds required by some bacteria to grow. These bacterial species are unable to synthesize themb. Cannot carry out denovo synthesisc. Amino acids, purines and pyrimidines, vitamins7. Identify a fastidious organism based on its growth requirements a. Growth factors8. Recall the definitions of the different types of growth media a. Synthetic medium: all component molecules are knownb. Minimal medium: Contains only those ingredients required for growth of a given organismc. Complex medium: ingredients of undefined composition9. Rank growth media in terms of complexity a. Look at the macro molecules and if it contains growth factors if it’s a F organism and contains growth factors it is minimal, if it has yeast and shit it is complex.10. Name a type of medium based on its given composition 11. Identify in which medium a given organism can grow 12. Compare and contrast selective and differential media a. Selective: Inhibits the growth of certain microbes but allows others to growb. Differential medium indicates whether certain chemical reactions occuri. Medium containing a pH indicator13. Identify a selective or differential medium based on its description 14. Explain what a pure culture is a. Population derived from a single organismb. Individual species are studied in pure culturesc. Need to be isolated15. Explain what aseptic methods are a. Methods used to avoid contamination16. Explain the general strategy in isolating pure bacterial cultures a. Streaking cells with an inoculation loop spreads the cells out so individual cells can grow isolated from other cells.17. Explain the concept of enrichment culture a. Uses a growth medium that is selective for growth of desired microbes and counter selective for othersb. Usually performed on samples of microbial communities to increase the fraction of microbial species that can carry out specific metabolic processes.c. Enrichment medium contains a specific nutrient that only certain species can usei. Microbe that can sue that specific nutrient will only
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