AP Bio CH.6 Exam
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/85
There's no tags or description
Looks like no tags are added yet.
86 Terms
The start and end states of a reaction are fixed. Enzymes CANNOT change ΔG; they only dictate the speed (rate) of the reaction
The totality of an organism’s chemical reactions; an emergent property that arises from orderly molecular interactions in a cell
A series of defined steps beginning with a specific molecule that is altered in a series of steps by specific enzymes to yield a product
Breakdown pathways that release energy by breaking down complex molecules into simpler compounds ("downhill" avenues; exergonic; -ΔG; increases system stability)
A major catabolic pathway that breaks down glucose and oxygen into carbon dioxide, water, and energy for cellular work (ΔG = -686 kcal/mol)
Pathways that consume energy to build complicated molecules from simpler ones ("uphill" avenues; endergonic; +ΔG; decreases system stability)
Synthesis of an amino acid from simpler molecules, protein synthesis from amino acids, and building up glycogen & fat stores
The study of how energy flows through living organisms
A process where stored chemical energy in organic molecules is converted to make light (e.g., dinoflagellates in ocean waves, fireflies)
The capacity to cause change, rearrange a collection of matter, or perform work against opposing forces like gravity and friction
Energy associated with the relative motion of objects, which can perform work by imparting motion to other matter
Thermal energy is kinetic energy associated with the random movement of atoms or molecules; Heat is thermal energy in transfer from one object to another
A form of kinetic energy that can be harnessed to perform work, such as powering photosynthesis in green plants
Energy that matter possesses because of its location or structure when it is not presently moving
Potential energy available for release in a chemical reaction due to the arrangement of electrons in the bonds between atoms
The study of energy transformations that occur in a collection of matter
System refers to the matter under study; Surroundings refer to everything outside the system (the rest of the universe)
An isolated system cannot exchange energy or matter with its surroundings. An open system freely exchanges both energy and matter (organisms are open systems)
Energy can be transferred and transformed, but it cannot be created or destroyed. (e.g., Chemical energy in fish eaten by a bear becomes kinetic energy of running or potential energy as fat)
Every energy transfer or transformation increases the disorder (entropy) of the universe. Most chemical energy is lost as unusable heat
A measure of molecular disorder or randomness within a system; increases as energy becomes more dispersed
A process that leads to an increase in entropy and can proceed without requiring an input of energy (can be fast or slow)
A process that leads to a decrease in entropy and occurs only if energy is continuously supplied
Organisms are islands of low entropy. Local order (e.g., protein synthesis, cell structure) increases at the expense of an even greater increase in total entropy of the surroundings
They are open systems that expend energy and create local order while releasing heat and waste, causing a net increase in universal entropy
The portion of a system’s energy that can perform work when temperature and pressure are uniform throughout a living cell
ΔG = G(final state) - G(initial state)
ΔG must be negative (ΔG < 0), meaning the system loses free energy and moves to a more stable final state
Unstable systems have high G, high work capacity, and a strong tendency to change; Stable systems have lower G and lower work capacity
A state of maximum stability where forward and reverse reactions occur at equal rates (ΔG = 0; G is at its lowest possible valley; system can do no work)
A cell that has reached metabolic equilibrium is dead. Metabolism is kept out of equilibrium because open systems constantly intake matter/energy and expel waste, and products become reactants for the next step
A chemical reaction that proceeds with a net release of free energy (ΔG is negative, spontaneous, energy down hill, increases stability)
A chemical reaction that absorbs free energy from its surroundings (ΔG is positive, nonspontaneous, energy up hill, stores free energy)
Respiration: ΔG = -686 kcal/mol (exergonic). Photosynthesis: ΔG = +686 kcal/mol (endergonic, powered by solar light energy)
Breaking bonds does NOT release energy—it REQUIRES energy. Energy is released when NEW bonds form that are lower in free energy than the original reactants
If a forward reaction is exergonic, its reverse reaction MUST be endergonic by the exact same numerical magnitude (e.g., -686 vs +686 kcal/mol)
1) Chemical work (pushing endergonic reactions) 2) Transport work (pumping substances across membranes against gradients) 3) Mechanical work (ciliary beating, muscle contraction, chromosome movement)
The use of an exergonic process to drive an endergonic one, primarily mediated by ATP in cells
Adenosine Triphosphate: composed of ribose (sugar), adenine (nitrogenous base), and a chain of three phosphate groups
All three phosphate groups carry negative charges that fiercely repel each other, creating intense chemical instability and high potential energy
ATP + H2O -> ADP + Pi; exergonic reaction that releases 7.3 kcal of energy per mole under standard conditions (ΔG = -7.3 kcal/mol)
Phosphorylation is the transfer of a phosphate group from ATP to another molecule. The recipient molecule is a "phosphorylated intermediate," which is more reactive and unstable
Glutamic Acid + Ammonia -> Glutamine (+3.4 kcal/mol) coupled with ATP Hydrolysis (-7.3 kcal/mol) yields a Net ΔG of -3.9 kcal/mol (exergonic & spontaneous)
ATP noncovalently binds to motor proteins, then hydrolyzes to ADP + Pi. This causes a conformational shape change that makes the motor protein "walk" along cytoskeletal tracks
ATP phosphorylates transport proteins, adding a phosphate group to induce a shape change that pumps solutes against their concentration gradient (active transport)
ATP is continuously regenerated by adding Pi to ADP using exergonic breakdown energy from catabolism. Unbelievably efficient: muscle cells recycle their entire ATP pool in <1 minute; 10 million ATPs consumed/regenerated per second per cell
A chemical agent that speeds up a reaction without being consumed by the reaction
A biological macromolecule catalyst (mostly proteins) that speeds up specific metabolic reactions by lowering activation energy barriers
Amylase (breaks down starches/carbs into simple sugars), Lipase (pancreatic enzyme breaking down fats), Protease (breaks down proteins into peptides/amino acids), Sucrase (hydrolyzes sucrose into glucose and fructose)
The initial investment of energy required to contort reactant molecules so their bonds can break and reach the transition state
The highly unstable, contorted, high-energy peak state that reactants must reach before old bonds break and new bonds form
1) High temperatures denature cellular proteins and kill cells. 2) Heat non-selectively speeds up ALL reactions, not just the needed ones
1) Active site acts as a template to properly orient two or more substrates. 2) Active site clutches and stretches substrate bonds toward transition state form. 3) Active site provides a conducive microenvironment (e.g., acidic pH). 4) Direct participation of active site amino acid R-groups in temporary covalent bonding
Substrate is the specific reactant an enzyme acts on. Binding creates a temporary Enzyme-Substrate Complex
A restricted pocket or groove on the surface of an enzyme formed by a few specific amino acids where catalysis occurs
Substrate entry into the active site triggers weak bonds that induce a subtle shape change in the enzyme, clutching the target tightly to catalyze the reaction (replaces old rigid lock-and-key model)
1) Entry: Substrates enter active site; induced fit secures them. 2) Catalysis: Active site lowers EA. 3) Conversion: Substrates converted to products. 4) Release: Products expelled; enzyme restored unchanged for next cycle
A single enzyme molecule typically processes about 1,000 substrate molecules per second
Occurs when substrate concentration is high enough that all active sites are continuously engaged. Reaction rate can then only increase by adding more enzyme
Up to optimal temp, reaction rate increases due to rapid molecular collisions. Past optimal temp, thermal agitation breaks weak hydrogen/ionic bonds, denaturing the protein
Human enzymes: optimal at ~37°C (35–40°C); Thermophilic bacteria enzymes: optimal at ~75°C (70°C or higher)
Deviations from optimal pH disrupt hydrogen and ionic bonds, denaturing the enzyme. Most enzymes prefer pH 6–8; Pepsin (stomach) optimal at pH ~2; Trypsin (intestines) optimal at pH ~8; Lysosomal enzymes optimal at pH ~4.5
Nonprotein helpers for catalytic activity. Inorganic cofactors include zinc, iron, or copper ions; Organic cofactors are called Coenzymes (e.g., vitamins)
Inhibitor resembles natural substrate and directly binds to the active site, physically blocking the substrate
YES. Can be overcome by flooding the system with excess natural substrate so substrate molecules outcompete inhibitor molecules for active sites
Inhibitor binds to an allosteric (alternative) site away from active site, causing a conformational shape change that warps the active site
NO. Increasing substrate concentration has zero effect because the active site shape is warped and inefficient
To achieve flexible metabolic control by offering two distinct ways to respond to changing cellular environments and requirements
Toxins/Poisons (form permanent covalent bonds with amino acids), Pesticides (inhibit key nervous system regulatory enzymes in pests), Penicillin (antibiotic that inhibits enzymes forming bacterial cell walls)
Gene mutations change amino acid sequences. If altered amino acids in an active site give a novel, beneficial function under environmental pressure, natural selection favors the mutated gene
Any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate (allosteric) site
Allosteric Activator binds to a regulatory site and locks all subunits into the stable functional ACTIVE form ("ON" switch); Allosteric Inhibitor locks all subunits into the non-functional INACTIVE form ("OFF" switch)
ATP allosterically inhibits catabolic enzymes when energy supply exceeds demand; ADP allosterically activates catabolic enzymes when energy is needed to regenerate ATP
A type of allosteric activation where a single substrate binding to one active site forces all other subunits to snap into the active conformation (e.g., O2 binding to hemoglobin in RBCs)
A negative feedback mechanism where the end product of a metabolic pathway acts as an allosteric non-competitive inhibitor to an early enzyme in its own pathway
Prevents chemical chaos, conserves chemical resources and ATP, and maintains thermodynamic balance between order and disorder
Synthesis of isoleucine from threonine: As isoleucine accumulates, it binds to an allosteric site on Enzyme 1 (threonine deaminase), halting its own production
Cells organize pathways by assembling multi-enzyme complexes or anchoring enzymes into specific organelle membranes (e.g., cellular respiration enzymes located in mitochondria)
Climbing ladder: kinetic energy of muscle movement converts to potential energy (max potential on platform). Diving: potential energy converts to kinetic energy. Water entry: kinetic energy transfers to water and dissipates as heat via friction
1st Law: Bear converts chemical potential energy of fish into kinetic energy of running. 2nd Law: Heat dissipation and small metabolic waste molecules (CO2, H2O) increase universal entropy
Growing on tree: Stored potential chemical energy (sugars from photosynthesis).
Falling: Potential energy converts to kinetic energy.
Digested: Chemical energy extracted by catabolism to power cellular work
The combination of Glutamic acid + Ammonia + ATP contains MORE free energy than Glutamine + ADP + Pi
A mutation changing amino acids in the active site can cause the enzyme to fail to bind substrates or fail to undergo induced fit shape changes
Measure reaction rate while gradually increasing substrate concentration. If the reaction rate recovers to normal maximum velocity, it is competitive; if it stays suppressed, it is non-competitive
Exergonic, because snapping the necklace allows chemicals to react and release energy out of the system in the form of light
Diffusion across a membrane is spontaneous (-ΔG) because systems naturally move down concentration gradients toward higher disorder/entropy without requiring energy