Chapter 12: Bioenergetics and Regulation of Metabolism Flashcards
(52 cards)
Biological Systems.
They’re considered open systems because they exchange both energy and matter with the environment. Energy is exchanged in the form of mechanical work when something is moved over a distance or is heat energy. Matter is exchanged through food consumption and elimination as well as respiration.
Internal energy.
Some of all of the different interactions between and within atoms in the system; Vibration, rotation, linear motion, and stored chemical energies all contribute.
Closed system.
Most biochemical studies are performed on the cellular subcellular level rather than the entire Organism. These systems are considered closed because there are no exchange of matter within the environment. Because the system’s closed, the changing internal energy can only come in the form of work or heat. This can be expressed mathematically through the first law of thermodynamics. Working thermodynamic refers to changing pressure and volume. These are constant in most living systems, so the quantity of interest in determining internal energy is heat.
Bioenergetics
Term used to describe energy States and biological system.
Entropy
Measure the degree of disorder or energy dispersion in the system. It carries the units of J/K.
Enthalpy
Measure the overall change in heat of the system during a reaction.
Free energy.
ΔG = ΔH - TΔS
Spontaneous reactions proceed in the forward direction, exhibit a net loss of free energy, and therefore have a negative ΔG. Non spontaneous reactions exhibit a net gain of energy and have the positive ΔG. Free energy approaches 0 as the reaction proceeds in equilibium.
Physiological Conditions.
ΔG= ΔG ° + RTln(Q)
Standard free energy ΔG ° Is the energy that occurs at standard concentration of 1M, pressure of 1 ATM and temperature of 25°C. The modified standard state is that [H+]=10^-7 and the pH is 7. ΔG ° Is giving the special symbol ΔG °’ Indicating that it is standardized to neutral buffers used in biochemistry.
Which is the preferred long term energy storage?
fat
What does ATP stands for?
Adenosine triphosphate.
A complete combustion of fat results in how much energy?
9 kcal/g
Complete combustion of Carbohydrates?
3kcal/g
How is ATP formed?
From substrate level phosphorylation as well as oxidative phosphorylation. Most of the ATP cells produced by mitochondrial ATP synthase. But some ATP is produced during glycolysis and the citric acid cycle. Is generated from ADP and Pi.
How much energy does ATP provide?
30.5kJ/mol
Difference between ATP, ADP and AMP
ATP is consumed either through Hydrolysis or the transfer of phosphate group to another molecule. If one phosphate group is removed, adenosine diphosphate (ADP) produce. If two phosphate groups are removed, adenosine monophosphate (AMP) is produced.
What is more stable, ADP or ATP?
The negative charges on the phosphate groups experience repulsive forces within another in ADP and P molecules that form after hydrolysis are stabilized by resonance.
Hydrolysis and coupling.
ATP hydrolysis is most likely to encounter in the context of coupled reactions. Many coupled reactions use ATP as an energy source. ATP cleavage is the transfer of high energy phosphate group from ATP to another molecule. Generally, this activates or inactivates the target molecule. With this phosphoryl group transfer, the overall free energy reaction will be determined by taking the sum of the free energies of the individual reactions.
Half reactions.
Divide oxidation reduction reactions into their half reactions component to determine the number of electrons being transferred.
Electron carriers.
High energy electron carriers, these are Soluble and include NADH, NADPH, FADH2, ubiquinone, cytochromes, and glutathione. As electrons are passed down the electron transport chain, they give up free energy to form proton motive force across the inner mitochondrial membrane. Membrane bound electron carriers embedded within the end of mitochondrial membrane.
Flavoproteins
Container a modified vitamin B or riboflavin. They function as coenzymes for enzymes in the oxidation fatty acids, the decarboxylation of fire and the reduction of glutathione.
Metabolic States.
Biochemist seeks a state of homeostasis, is a Physiological tendency towards a relative stable state that is maintained and adjusted, often with the expenditure of energy. It is different from equilibrium, which allows us to store potential energy.
Postprandial (absorptive ) state.
It is also called the absorptive or well fed state. Occurs shortly after eating. These days marked by greater anabolism and full storage than catabolism. You generally last three to five hours after eating a meal. Just after eating, blood glucose level rise and stimulate the release of insulin. The three major target tissues for insulin are delivered muscle and adipose tissue. Insulin promotes glycogen synthesis in the liver and muscle. After the glycogen stores are filled, the liver converts excess glucose to fatty acids and triglycerides. Most of the energy needs of the liver and met by oxidation of excess amino acids. Nervous tissues and red blood cells are notably insensitive to insulin. Nervous tissue derives energy from oxidizing glucose to CO2 and water in both well fed and normal fasting stages. Red blood cells can only use glucose anaerobically.
Post absorptive (fasting) state.
Glucagon, cortisol, epinephrine, non epinephrine, and growth hormones oppose the action of insulin. These remains are sometimes termed counterregulatory hormones because of their effects on skeletal muscle, adipose tissue and liver. In the liver, glycogen degradation and the release of glucose into the blood are simulated. Hepatic glucose genesis is also stimulated by Glucagon, but the response is lower than of glycogenolysis. Amino acids and fatty acids can provide the necessary carbon skeleton and make energy required for gluconeogenesis.
Prolonged fasting, (Starvation)
levels of Glucagon and epinephrine are markedly elevated during starvation. There’s a rapid degradation of glycogen storages in the liver. After about 24 hours, gluconeogenesis is the predominant source of glucose for the body. Lipolysis is rapid, resulting in an excess ascetical aid that is used in the synthesis of ketone bodies. After several weeks of fasting, the brain derives approximately 2/3 of its energy from ketones and 1/3 from glucose. This shift from glucose to ketones as a major fuel reduces the quantity of amino acids that must be degraded to support gluconeogenesis, which spares proteins that are vital for function.
