Big Idea 2 Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis.

Growth, reproduction, and maintenance, of the organization of living systems require free energy and matter. Recommended reading: Chapter 6: Metabolism, OpenStax Biology

Constant inputs of energy Life is incredibly complex and ordered (inter- and intra- organismally). To function, constant inputs of energy are required. Prolonged (dis)order = death. Living systems do not violate the second law of thermodynamics (entropy). What is this? Increasing disorder is offset by biological processes that maintain or increase order. How might this work? 2nd Law = Entropy increases over time. Photosynthesis products are used as reactants in respiration.

Energy - Biochemistry What types of energy are there? Where is energy stored? How does energy get converted and subsequently stored? Why might there be different amounts of energy in different types of macromolecules?

What is a biological process? What are some examples? Examples (more on this later) Calvin Cycle Krebs Cycle Light-Dependent Reactions Glycolysis Fermentation

Offsetting Processes The products of one become the reactants of others. However the input of energy must always be greater than the loss of energy over time. Cycle(s) of life, chemically, how does this look? Series of negative feedback loops exist throughout nature. What are examples of these? Certain things that consume energy are offset by processes that produce energy.

Free Energy Thermodynamic quantity equivalent to the capacity of a system to do work.(1) An exergonic reaction refers to a reaction where energy is released. Because the reactants lose energy (G decreases), Gibbs free energy (ΔG) is negative under constant temperature and pressure. (2) Some reactions require activation energy EA (energy to get the reaction going!) Here is an endergonic reaction of ATP to give energy. Breaking down the ATP formed ADP and Pi is an exergonic reaction, where ΔG is less than 0.

Calculating Gibb’s Free Energy ΔG = ΔH − TΔS ΔG = change in Gibbs free energy ΔS = change in entropy ΔH = change in enthalpy T = absolute temperature (in Kelvin = C° + 273) From OpenStax, pg. 181: [The standard free energy change of a chemical reaction is expressed as an amount of energy per mole of the reaction product (either in kilojoules or kilocalories, kJ/mol or kcal/mol; 1 kJ = 0.239 kcal) under standard pH, temperature, and pressure conditions. Standard pH, temperature, and pressure conditions are generally calculated at pH 7.0 in biological systems, 25 degrees Celsius, and 100 kilopascals (1 atm pressure), respectively. It is important to note that cellular conditions vary considerably from these standard conditions, and so standard calculated ΔG values for biological reactions will be different inside the cell.]

Gibb’s Free Energy If energy is released, this is a negative (the products have less energy than the reactants). If it is taken in, this is a positive. Look at each of the processes shown, and decide if it is endergonic or exergonic. In each case, does enthalpy increase or decrease, and does entropy increase or decrease? (a) a compost pile decomposing, (b) a chick hatching from a fertilized egg, (c) sand art being destroyed, and (d) a ball rolling down a hill.

Graphing comparisons of Ender- and Exer-gonic Reactions How do enzymes help when energy is required to make a product?

Select a Biological Process from our list before These processes are “sequential” meaning they can be entered at any point. As a result, if I took a pill (not in Ibiza), that was full of NADH, how might that influence ethyl alcohol fermentation (would it increase/decrease the amount of alcohol and how?) How might this apply to the supplements we take, what might they actually do when considering biological processes?

Why do organisms need energy? What are examples of ectotherms (use of external thermal energy to help regulate and maintain body temperature)? What are examples of endotherms (the use of thermal energy generated by metabolism to maintain homeostatic body temperatures)? Perform activities for: Growth. Maintain organization. Reproduce (when creating offspring, you need additional energy to grow these new organisms).

Varying Reproductive Strategies When do many organisms reproduce (plants and animals)? Why would this make sense in terms of energy?

Metabolic Rates Getting cats fixed affects their metabolic rates – resting metabolic rate. Given your size – what is your resting metabolic rate? Link! Mine is 1962 calories/day (8209kJ?).

In our labs When you increased the amount of producers in a population, what should have happened to the total population of the community? If you decreased decomposers, how might this impact the community? Amount of organisms in trophic levels affect each other. Therefore, changes in the energy available to an ecosystem fluctuates and so, too, does the organisms comprising the ecosystem.

In our labs - continued Autotrophs (chemo- or photo-) convert free energy from inorganic components. What types of different macromolecules do we (heterotrophs) get energy from?

Energy capturing needs Electron Acceptors NADP+ in Photosynthesis O2 in respiration. Why?

Photosynthesis and Cellular Respiration

Respiration C6H12O6 + 6(H2O) + 6(O2) → 12(H2O) + 6(CO2) + 2820 kJ

Biological Energy Processes Summarize the process - How is the energy obtained? What is the energy specifically obtained from/converted? - What molecules are electron acceptors in the process? - How is an electrochemical gradient involved? Autotrophs (inorganic --> organic) --> Chemosynthesis --> Photosynthesis Heterotrophs (organic --> organic) --> Metabolism of carbs, lipids, and proteins for energy --> Fermentation (lactic acid or ethyl alcohol)