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Metabolism the totality of an organism's chemical reactions
Metabolic pathway begins w/ a specific molecule, which is then altered in a series of defined steps, resulting in a certain product
Catabolic pathways aka breakdown pathways de-gradative pathway; release energy by breaking down complex molecules to simpler compounds
Anabolic pathways aka biosynthetic pathways consume energy to build complicated molecules from simpler ones
Bioenergetics study of how energy flows though living organisms
Energy the capacity to cause change
Kinetic energy energy associated with the relative motion of objects. Moving objects can perform work by imparting motion to other matter
Examples of kinetic energy motion of a cue stick to push the cue ball which in turn moves the other pool balls; water gushing through dam turns turbines; contraction of leg muscles pushes bicycle pedals
Heat aka thermal energy kinetic energy associated with random movement of atoms or molecules
Light energy a type of energy that can be harnessed to perform work such as powering photosynthesis
Potential energy energy that matter possesses because of its location or structure; it is not kinetic
Example of potential energy water behind a dam possesses energy because of its altitude above sea level
Chemical energy the potential energy available for release in a chemical reaction
Thermodynamics the study of the energy of transformations that occur in a collection of matter
System the matter under study
Surroundings everything outside the system
Isolated system system unable to exchange energy or matter with its surroundings. Eg, liquid in a thermos bottle
Open system system in which energy and matter can be transferred between the system and its surroundings. Eg, organisms because they absorb energy and release heat and metabolic waste products to the surroundings
1st law of thermodynamics aka the principle of conservation of energy the energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created or destroyed.
The first law of thermodynamics is aka ___ the principle of conservation of energy
Entropy a measure of disorder or randomness
2nd law of thermodynamics every energy transfer or transformation increases the entropy of the universe. Another way to say it is: for a process to occur spontaneously, it must increase the entropy of the universe.
spontaneous can occur w/o input of energy; does not imply quickness. Some processes may be instantaneous like an explosion; some might be slow like the rusing of an old car
universe the system plus its surroundings
how does the 2nd law of thermodynamics explain the diffusion of a substance across a membrane? 2nd law is a trend twd randomness. Equal concentrations on both sides is more random distribution than unequal concentrations. Diffusion to region of less concentration increases entropy, per 2nd law.
Describe the forms of energy found in an apple as it grows on tree, then falls, and is digested by someone who eats it potential energy in hanging from tree. Kinetic energy as it falls to ground. When apple is digested some chemical energy does work, the rest is lost as thermal energy.
Free energy the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system. Eg, in a living cell.
Enthalpy total energy in a biological system
Equilibrium maximum stability
Exogenic reaction rxn with net release of free energy. Change in free energy is negative.
Endergonic reaction rxn that absorbs free energy from its surroundings. Change in free energy is positive.
Cellular respiration uses glucose and oxygen, which have high levels of free energy, and release CO2 and H2O, which have low levels of free energy. Is respiration spontaneous? spontaneous
Cellular respiration uses glucose and oxygen, which have high levels of free energy, and release CO2 and H2O, which have low levels of free energy. Is it exergonic or endergonic? exergonic
Cellular respiration uses glucose and oxygen, which have high levels of free energy, and release CO2 and H2O, which have low levels of free energy. What happens to the energy released from glucose? the energy released from glucose is used to do work in the cell or is lost as heat
A key process in metabolism is the transport of H+ across a membrane to create a concentration gradient. Other processes can result in an equal concentration of H+ on each side. Which arrangement of H+ allows the H+ to perform work in this system? H+ can perform work only if their concentration on each side of membrane differ. When H+ concentrations are the same, the system is in equilibrium and can do no work.
3 main kinds of work cells do chemical work, transport work, mechanical work
chemical work by cells pushing endergonic rxns, which would not occur spontaneously, eg, synthesizing polymers
transport work by cells pumping substances across membranes agains the direction of spontaneous movement
mechanical work by cells eg, beating of cilia, contraction of muscle cells, movement of chromosomes during cellular reproduction
Energy coupling use of an exergonic process to drive an endergonic one. A key feature in the way cells manage their energy resources to do work.
Adenosine triphosphate (ATP) contains ribose (a sugar), adenine (a nitrogenous base), and 3 phosphate groups. Plays role in energy coupling. Also used to make RNA.
Phosphorylated referring to a molecule that is covalently bonded to a phosphate group
How does ATP transfer energy from exergonic to endergoinc reactions in the cell? ATP transfers energy to endergonic reactions by phosphorylating other molecules. Exergonic processes phosphorylate ADP to regenerate ATP.
Enzyme a macromolecule that acts as a catalyst
Catalyst a chemical agent that speeds up a rxn w/o being conumed by the rxn
Activation energy aka free energy of activation the initial investment of energy for starting a rxn; the energy required to contort the reactant molecules so the bonds can break; the amt of energy needed to push the reactants over an energy barrier so that the downhill part of the rxn can begin
Transition state an unstable condition in which bonds of the reactants can be broken, represented by the peak of the energy of activation hill
Substrate the reactant an enzyme acts on
Enzyme-substrate complex a temporary complex formed when an enzyme binds to its substrate molecule(s)
Active site a restricted region of the enzyme that binds to the substrate. Typically a pocket or groove where catalysis occurs. Usually formed by only a few of the enzyme's amino acids.
The specificity of an enzyme is attributed to a compatible fit between the shape of its ______ ____ and the shape of its _________. active site, substrate
Induced fit induced by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate
When is an enzyme said to be saturated? when the concentration of substrate is high enough that all enzyme molecules have their active sites engages. As soon as the product exits an active site, another substrate molecule enters.
Optimal conditions the best conditions under which an enzyme works, favoring the most active shape for the enzyme molecule
Cofactor any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Can be permanently bound to active site or may bind loosely with the substrate during catalysis.
Coenzyme an organic cofactor. Most vitamins function as coenzymes in metabolic rxns.
Competitive inhibitors reduce productivity of enzymes by blocking substrates from entering active sites
Noncompetitive inhibitors impede enzymatic rxns by binding to parts of the enzyme other than the active site
Why don't all spontaneous rxns occur instantly? a spontaneous rxn is exergonic. However, if it has a high activation energy that is rarely attained, the rate of the rxn may be low.
Why do enzymes act only on very specific substrates? only the specific substrate(s) will fit properly into the active site of an enzyme, the part of the enzyme that carries out catalysis
Allosteric regulation any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site. May result in either inhibition or stimulation of an enzyme's activity
Regulatory site aka allosteric site
Binding of an activator to a regulatory site stabilizes the shape that has functional active sites
Binding of an inhibitor to a regulatory site stabilizes the inactive form of the enzyme
Cooperativity a kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the others, facilitating binding of subsequent substrate molecules
Caspases protein-digesting enzymes that play an active role in inflammation and cell death
Feedback inhibition a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway
How can an activator and an inhibitor have different effects on an allosterically regulated enzyme? activator binds in a way that stabilizes the active form of the enzyme; the inhibitor stabilizes the inactive form
Catabolism:anabolism :: exergonic:_____ endergonic
Most cells cannot harness heat to perform work because temperature is usually _______ throughout the cell uniform
If enzyme in solution is saturated with substrate, which is the most effective way to obtain faster yield of more product: add more enyme or more heat or more substrate more enzyme
If enzyme is added to soln where substrate and product are in equilibrium, what would occur? nothing. The rxn would stay at equilibrium.
Some bacteria are metabolically active in hot springs because their enzymes have high _______ temperatures. optimal
Created by: stinglasher23



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