- Define the following terms and explain how they are relevant to driving microbial biomass:
- Catabolism
- Anabolism
- enthalpy
- entropy
- DG
- DG is defined by intrinsic properties of a reaction. What two other factors contribute? (see lecture slides and page 491 of your text).
- The phosphorylation of glucose has a DGo’ of +13.8 kJ/mol. Will this reaction proceed in the forward reaction? Why or why not?
- Explain how the concept of “additivity of energy change” is central to the phosphorylation of glucose as it occurs during the first step in glycolysis (EMP pathway).
- ATP is an energy carrier. How is energy stored by ATP and what are THREE ways that ATP can transfer energy?
- What are THREE commonly used electron carriers? How do they store energy?
- What is an example of a specific concentration gradient that stores energy which can be used to generate ATP?
- Fill in the following table describing central metabolic pathways. For each substrate indicate how carbons they contain. For each product, indicate how many carbons they contain and how many molecules are produced from 1 molecule of the substrate.
| substrate | Product(s) | NET ATP produced | Number and type of electron carriers produced | |
| Glycolysis (EMP) | 1 Glucose (6C) | 2 Pyruvate (3C) | 2 | 2 NADH |
| TCA cycle | ||||
| Fermentation (just pick a pathway that produces your favorite fermented product) |
- Humans only contain the enzymes to digest starch, lactose, and sucrose. How are humans able to get energy from eating polysaccharides or glycan fibers in fruit, lettuce or tomatoes?
- What are the three pathways involved in glucose catabolism that have been described in prokaryotes?
- In the following, indicate which pathways from question 10, are used.
- Generates the most energy
- Used by enteric bacteria to grow on intestinal mucus
- Used to generate substrates for anabolic reactions such as purines needed for DNA or RNA
- In the presence of oxygen, indicate which of the following pathways are necessary for complete oxidation of glucose. Place the pathways in order used for complete oxidation of glucose. Indicate which, if any, terminal electron acceptor
Pathways: EMP, fermentation, ETS, TCA
Terminal electron acceptors: O2, nitrate
- In the absence of oxygen, some cells perform anaerobic respiration. Which of the above pathways and/or terminal electron acceptors would be necessary?
- Distinguish between glyoxylate bypass and gluconeogenesis. What is the function of both and which pathways do they involve?
- Describe two specific positive benefits of specific gut microbiota catabolic pathways which promote human (or other mammal) health.
