CH 8 BIO M02A

metabolism

the sum of all chemical reactions that occur within a living organism's cells, converting food into energy needed for growth, reproduction, movement, and other vital functions

metabolic pathways

a series of biochemical reactions that occur in a cell to change a substance into another substance or usable material

anabolic pathways

chemical reactions that build larger molecules from smaller ones, using energy in the process

catabolism

a biological process that breaks down large molecules into smaller units, releasing energy in the process

catabolic pathways

a series of chemical reactions that break down complex molecules into simpler ones, releasing energy in the process

substrate

reactant - starting material

product

the substance or molecule that is formed as a result of a biological process

enzyme

proteins that speed up chemical reactions in living things by lowering the energy required for them to occur

energy

the ability to produce change or perform work

potential energy

the stored energy an object possesses due to its position or internal structure

kinetic energy

the energy an object possesses due to its motion

thermal energy

associated with random movement of atoms or molecules

heat

thermal energy in transfer from one object to another

Chemical energy

potential energy available for release in a chemical reaction, stored in bonds of chemical substances

Electrical energy

results from movement of charged particles

Mechanical energy

moving matter

Radiant energy

the energy transmitted through electromagnetic waves, primarily from sunlight

first law of thermodynamics

the energy of the universe is constant: Energy can be transferred and transformed, but it cannot be created or destroyed

second law of thermodynamics

in any natural process, the total entropy of a system and its surroundings will always increase, meaning that disorder or randomness in a closed system naturally tends to increase over time, and heat always flows from a hotter to a colder body

entropy

a measure of disorder or randomness within a system, essentially signifying the tendency for things to move towards a more disorganized state, often explained as the "unavailable energy" within a closed system

∆S

represents the change in entropy of a system, essentially signifying the change in disorder or randomness within that system; a positive ∆S indicates an increase in disorder, while a negative ∆S means a decrease in disorder.

enthalpy

the total heat content of a system, essentially the sum of a system's internal energy and the product of its pressure and volume

∆H

represents the change in enthalpy, which is a thermodynamic property that measures the heat gained or lost by a system during a chemical reaction at constant pressure

Free Energy

the amount of energy available to do work within a system, essentially the usable energy that can be harnessed from a chemical reaction, and is often represented by the symbol "∆G"

∆G of a reaction, predict if the reaction will be spontaneous or not

A reaction is considered spontaneous if its ∆G (Gibbs free energy change) is negative, meaning a negative ∆G indicates a spontaneous reaction, while a positive ∆G indicates a non-spontaneous reaction.

circumstances a reaction will be spontaneous

when it occurs naturally without any external energy input, which means its Gibbs free energy change (ΔG) is negative; this typically happens when a reaction experiences a decrease in enthalpy (ΔH < 0) and an increase in entropy (ΔS > 0), signifying a release of heat and increased disorder in the system, respectively.

endergonic

Positive ∆G

a chemical reaction that requires an input of energy to proceed,meaning it absorbs energy from its surroundings to form products with more energy than the reactants, making it a non-spontaneous process; essentially, the reaction "takes in" energy

exergonic

Negative ∆G

a chemical reaction that releases free energy, meaning the products of the reaction have less free energy than the reactants, allowing the reaction to occur spontaneously without additional energy input; essentially, energy is "exiting" the system

type of reaction breaks down ATP

hydrolysis. This means that a water molecule is used to break the bonds within the ATP molecule, releasing energy and converting it to ADP (adenosine diphosphate)

hydrolysis of ATP

a catabolic reaction that releases chemical energy from adenosine triphosphate (ATP) by breaking the bonds between its phosphate groups

net ∆G for a coupled reaction

negative; meaning the overall reaction is spontaneous because a coupled reaction combines a spontaneous reaction with a non-spontaneous reaction, resulting in a combined reaction that has a negative ∆G value, allowing the non-spontaneous reaction to occur

3 examples of cellular work driven by ATP

muscle contraction, active transport of molecules across cell membranes (like the sodium-potassium pump), and protein synthesis

spontaneous reactions may not occur spontaneously

even though the reaction is thermodynamically favored (meaning it will proceed towards products on its own), it can still have a high activation energy barrier, which means it needs a significant push to get started, causing the reaction to occur very slowly, making it seem like it's not happening spontaneously

transition stage

When the molecules have absorbed enough energy for the bonds to break, the reactants are in an unstable condition, when the molecule is neither a substrate or a product.

energy of activation

The initial investment of energy for starting a reaction—the energy required to contort the reactant molecules so the bonds can break

what enzymes do in terms of energy of activation and enzyme rate

lowering the activation energy of a chemical reaction, which in turn significantly increases the rate of the reaction; essentially, they make reactions happen faster by requiring less energy to initiate the process, allowing for a quicker conversion of reactants into products

No, enzymes do not affect the change in free energy (ΔG) of a reaction

how enzymes facilitate formation of transition state

binding to the substrate molecules in their active site, creating an environment that stabilizes the high-energy, unstable transition state configuration, effectively lowering the activation energy required for the reaction to proceed, thus speeding up the reaction rate; essentially, the enzyme acts as a template that optimally positions the reactants to reach the transition state more easily

induced fit

a model in biochemistry where an enzyme's active site slightly changes shape to better fit the substrate molecule once it binds. It brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction.

effects of pH and temperature on reaction rate

increasing temperature generally speeds up a reaction by increasing the kinetic energy of molecules, leading to more collisions, while pH affects the reaction rate by altering the charge and structure of reactant molecules, particularly important for enzyme-catalyzed reactions; in most cases, an optimal pH range exists where the enzyme functions best, with significant decreases in activity if the pH deviates too far from this range.

effect of substrate concentration on reaction rate

As substrate concentration increases, the rate of a chemical reaction initially increases rapidly, but eventually reaches a plateau where further increases in substrate concentration have little to no effect on the reaction rate

enzyme inhibitors

blocks the action of an enzyme

Km

concentration of the substrate at which half of the active sites of the enzyme are occupied by the substrate

Vmax

the maximum rate of reaction of an enzyme when it is saturated with substrate

effect of noncompetitive inhibitors.

binds to an enzyme at a site distinct from the active site (allosteric site), causing a change in the enzyme's shape that significantly reduces its catalytic activity, effectively lowering the maximum reaction rate (Vmax) without affecting the substrate binding affinity (Km) regardless of substrate concentration

essentially, it prevents the enzyme from properly converting substrate to product by altering its conformation, even when the substrate is bound to the active site.

noncompetitive inhibition binding

binds at an allosteric site separate from the active substrate binding site

the effect of noncompetitive inhibitors on Km.

no effect on the Km value of an enzyme, meaning it does not change the enzyme's affinity for its substrate

noncompetitive inhibitors on Vmax

decreases the Vmax of an enzyme reaction, adding more substrate cannot restore the original Vmax because the inhibitor binds to a site separate from the active site, effectively reducing the enzyme's catalytic activity regardless of substrate concentration

Describe the effect of competitive inhibitors

decreases enzyme activity by binding to the enzyme's active site, effectively blocking the natural substrate from accessing the site and preventing the reaction from occurring

Describe where competitive inhibitors bind on the enzyme

bind to the active site of an enzyme, which is the same location where the natural substrate binds

Describe the effect of competitive inhibitors on Km. Is more substrate required to reach 1/2Vmax?

increases the Km value of an enzyme, meaning that a higher concentration of substrate is needed to reach 1/2Vmax (half of the maximum reaction rate) because the inhibitor competes with the substrate for the active site on the enzyme, effectively reducing the enzyme's affinity for the substrate; therefore, more substrate is required to achieve the same reaction rate as without the inhibitor

Describe the effect of competitive inhibitors on Vmax. Can the same Vmax be reached without an inhibitor by adding an additional substrate?

A competitive inhibitor has no effect on the Vmax of an enzyme, meaning the maximum reaction velocity remains the same even in the presence of the inhibitor; however, a higher substrate concentration is needed to reach that Vmax due to the inhibitor competing for the active site, effectively increasing the apparent Km value.

allosteric activation

a regulatory mechanism that occurs when a molecule binds to an enzyme's allosteric site, which is separate from the active site, and increases the enzyme's activity

allosteric inhibition

a form of enzyme regulation where a molecule, called an allosteric inhibitor, binds to a specific site on an enzyme (the allosteric site) which is separate from the active site, causing a conformational change in the enzyme's structure that ultimately reduces its activity and prevents the substrate from binding effectively

cooperativity

a phenomenon where the binding of a molecule to one site on a protein influences the affinity of other binding sites on the same protein

feedback inhibition

a cellular mechanism where the end product of a biochemical pathway inhibits an enzyme earlier in the pathway, effectively preventing the overproduction of that product by regulating its synthesis when it reaches a certain concentration

Anabolism

a metabolic process that builds complex molecules from simpler ones, using energy in the form of adenosine triphosphate (ATP)