Biology Chapter on Metabolism and Energy Flow

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Questions and Answers

Which of the following statements correctly describes the relationship between metabolism and energy flow in living systems?

  • Metabolism is the study of energy flow through living systems, while energy flow describes the specific chemical reactions involved in these systems.
  • Metabolism is the process of converting energy from food into usable forms, while energy flow describes the movement of energy through ecosystems.
  • Energy flow is the process of photosynthesis, while metabolism is the process of cellular respiration.
  • Energy flow refers to the movement of energy through living systems, while metabolism includes all the chemical reactions within cells that involve energy. (correct)

What is the primary energy currency used by cells to perform immediate work?

  • Glucose
  • ATP (correct)
  • Carbon dioxide
  • Oxygen

How does the process of photosynthesis relate to the flow of energy in living systems?

  • Photosynthesis is the primary process for breaking down glucose molecules, releasing energy as heat.
  • Photosynthesis converts light energy into chemical energy stored in glucose molecules, making energy available to other organisms. (correct)
  • Photosynthesis releases energy from glucose molecules, providing energy for cellular processes.
  • Photosynthesis is the process of converting carbon dioxide into oxygen, which is then used by other organisms.

Which of the following is an accurate description of cellular respiration?

<p>Cellular respiration is the process of breaking down glucose molecules to release energy in the form of ATP. (D)</p> Signup and view all the answers

Which of the following statements is NOT true about the relationship between photosynthesis and cellular respiration?

<p>Both processes take place in the same cellular compartments. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the concept of bioenergetics?

<p>Bioenergetics is the study of how organisms use energy to build and break down molecules. (D)</p> Signup and view all the answers

Which of the following pairs of molecules would be considered energy storage molecules?

<p>ATP and glucose (D)</p> Signup and view all the answers

Which of the following processes occurs during the light reactions of photosynthesis?

<p>Capture of light energy and conversion into chemical energy (C)</p> Signup and view all the answers

Which of the following is NOT an example of potential energy?

<p>A moving car (A)</p> Signup and view all the answers

What type of energy is associated with the movement of molecules in the air?

<p>Kinetic energy (B)</p> Signup and view all the answers

What is the term for the energy stored within the bonds of molecules?

<p>Chemical energy (A)</p> Signup and view all the answers

What happens to the potential energy of a wrecking ball as it swings from its highest point to its lowest point?

<p>It is converted to kinetic energy. (B)</p> Signup and view all the answers

Which of the following is true about exergonic reactions?

<p>They release energy. (C)</p> Signup and view all the answers

What is the term for the minimum amount of energy required for a chemical reaction to occur?

<p>Activation energy (D)</p> Signup and view all the answers

What type of reaction is characterized by a positive change in free energy (∆G)?

<p>Endergonic reaction (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of an endergonic reaction?

<p>It releases energy. (C)</p> Signup and view all the answers

What is the role of enzymes in chemical reactions?

<p>To lower the activation energy of the reaction. (A)</p> Signup and view all the answers

What does the term "free energy" refer to in the context of chemical reactions?

<p>The energy available to do work. (C)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between endergonic and exergonic reactions in living cells?

<p>Exergonic reactions provide energy for endergonic reactions. (A)</p> Signup and view all the answers

What is the primary source of chemical energy for living cells?

<p>Food (A)</p> Signup and view all the answers

Which of the following processes would be considered an endergonic reaction?

<p>The synthesis of proteins from amino acids. (C)</p> Signup and view all the answers

What is the significance of the second law of thermodynamics in the context of free energy?

<p>It explains why energy transfers always result in some energy loss as heat. (B)</p> Signup and view all the answers

Which of the following scenarios would be most likely to involve a spontaneous reaction?

<p>The melting of ice into liquid water. (A)</p> Signup and view all the answers

What is the primary reason why enzymes are essential for life?

<p>They lower the activation energy of reactions, making them occur at a feasible rate. (A)</p> Signup and view all the answers

What is the primary difference between competitive and noncompetitive inhibition?

<p>Competitive inhibition occurs when the inhibitor binds to the enzyme's active site, preventing substrate binding, while noncompetitive inhibition occurs when the inhibitor binds to a site away from the active site, changing the enzyme's conformation and reducing its activity. (C)</p> Signup and view all the answers

What is the function of allosteric activators in enzymatic regulation?

<p>They bind to a site away from the active site, causing a conformational change that increases the enzyme's affinity for its substrate. (B)</p> Signup and view all the answers

Which of the following is an example of a cofactor?

<p>Iron (B)</p> Signup and view all the answers

What is the role of feedback inhibition in regulating enzyme activity?

<p>It involves the use of a reaction product to inhibit its own further production. (C)</p> Signup and view all the answers

Which of the following is NOT a mechanism of enzyme regulation?

<p>Degradation of the enzyme's active site (A)</p> Signup and view all the answers

How do statins, a type of drug used to lower cholesterol levels, work?

<p>They inhibit the enzyme HMG-CoA reductase, which synthesizes cholesterol. (A)</p> Signup and view all the answers

What is the primary challenge in drug discovery?

<p>Identifying a drug target molecule. (A)</p> Signup and view all the answers

Which of the following is TRUE about the role of vitamins in enzymatic regulation?

<p>Some vitamins act as coenzymes, contributing to enzyme function. (C)</p> Signup and view all the answers

What is the relationship between ATP and ADP in regulating enzyme activity?

<p>ADP activates the enzyme's activity, while ATP inhibits it. (B)</p> Signup and view all the answers

Which of the following is an example of a metabolic pathway that is regulated by feedback inhibition?

<p>All of the above (D)</p> Signup and view all the answers

What is the significance of understanding how enzymes work and how they can be regulated?

<p>All of the above (D)</p> Signup and view all the answers

How do drug designers use their knowledge of enzymes to develop new drugs?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following is NOT an example of a molecule that can regulate enzyme function?

<p>DNA (D)</p> Signup and view all the answers

What is the role of allosteric regulation in enzymatic activity?

<p>It changes the enzyme's shape, affecting its activity. (D)</p> Signup and view all the answers

Which type of enzyme regulation is involved when a product of a metabolic pathway inhibits an enzyme earlier in the pathway?

<p>Feedback inhibition (D)</p> Signup and view all the answers

What is the primary function of coenzymes in enzymatic reactions?

<p>They bind to the enzyme's active site and directly participate in the reaction. (C)</p> Signup and view all the answers

What is the primary function of enzymes in metabolic pathways?

<p>They regulate the speed of reactions. (A)</p> Signup and view all the answers

Which type of metabolic pathway breaks down polymers into their monomers?

<p>Catabolic pathways (A)</p> Signup and view all the answers

Which of the following is NOT an example of energy transformation?

<p>A rock rolling down a hill. (B)</p> Signup and view all the answers

According to the first law of thermodynamics, what happens to energy in the universe?

<p>Energy can be transferred and transformed, but not created or destroyed. (A)</p> Signup and view all the answers

Which of the following is a true statement regarding entropy?

<p>Entropy is a measure of order within a system. (D)</p> Signup and view all the answers

What is the main reason why living organisms require a constant energy input?

<p>To counteract the tendency towards increasing entropy. (A)</p> Signup and view all the answers

Which of the following is an example of an open system?

<p>A living cell. (D)</p> Signup and view all the answers

What is the main mechanism by which cells obtain usable energy from organic molecules?

<p>Converting organic molecules into ATP through a series of cellular reactions. (A)</p> Signup and view all the answers

What is the role of ATP in cellular processes?

<p>To act as an energy carrier that can be readily used by cells. (D)</p> Signup and view all the answers

Why do some energy transfers and transformations result in a loss of usable energy as heat?

<p>The second law of thermodynamics dictates that no energy transfer is 100% efficient. (D)</p> Signup and view all the answers

What is the significance of the breakdown of food molecules to produce energy for cellular processes?

<p>It releases energy that can be used to power cellular work. (A)</p> Signup and view all the answers

Which of the following correctly describes the relationship between anabolic and catabolic pathways?

<p>Anabolic pathways break down molecules, requiring energy, while catabolic pathways build molecules, releasing energy. (C)</p> Signup and view all the answers

What is the primary source of energy for plants?

<p>Light energy from the sun. (A)</p> Signup and view all the answers

Which of the following statements is true about the relationship between energy and entropy?

<p>Energy transfers can lead to changes in entropy levels within a system. (D)</p> Signup and view all the answers

Which of the following is NOT an example of cellular work powered by energy from ATP?

<p>Maintaining a constant body temperature. (D)</p> Signup and view all the answers

How does the second law of thermodynamics explain the challenge of maintaining order in living organisms?

<p>Living organisms require a constant energy input to counteract the natural tendency towards increasing entropy. (A)</p> Signup and view all the answers

What is the relationship between metabolism, anabolism, and catabolism?

<p>Metabolism encompasses both anabolic and catabolic pathways, representing the sum of all chemical reactions in a living organism. (D)</p> Signup and view all the answers

What is the primary role of enzymes in chemical reactions?

<p>They lower the activation energy needed for the reaction to proceed. (D)</p> Signup and view all the answers

Why is the induced-fit model a more accurate representation of enzyme-substrate binding than the lock-and-key model?

<p>The induced-fit model explains the conformational changes an enzyme undergoes upon substrate binding. (D)</p> Signup and view all the answers

What are the chemical reactants that bind to an enzyme called?

<p>Substrates (A)</p> Signup and view all the answers

Which of the following factors can influence the activity of an enzyme?

<p>All of the above (D)</p> Signup and view all the answers

What is the role of the active site in enzyme catalysis?

<p>It binds to the substrate and brings it into the correct orientation for reaction. (B)</p> Signup and view all the answers

How does an enzyme-substrate complex lower the activation energy of a reaction?

<p>By providing an alternative reaction pathway with a lower activation energy. (C)</p> Signup and view all the answers

Which of the following is NOT a way in which enzymes can promote the reaction of their substrates?

<p>Providing energy to the reactants. (C)</p> Signup and view all the answers

What is meant by the statement that enzymes are highly specific?

<p>An enzyme has a specific three-dimensional shape that only binds to one or a few specific substrates. (A)</p> Signup and view all the answers

How does the activity of an enzyme change when the temperature is increased beyond its optimal range?

<p>The activity of the enzyme decreases. (A)</p> Signup and view all the answers

What is denaturation in relation to enzymes?

<p>The process of an enzyme losing its shape and function. (B)</p> Signup and view all the answers

How can the activity of enzymes be regulated within a cell?

<p>All of the above (D)</p> Signup and view all the answers

What is the role of an inhibitor molecule in relation to enzymes?

<p>To bind to the active site and prevent substrate binding. (C)</p> Signup and view all the answers

What is the difference between cofactors and coenzymes?

<p>Cofactors are inorganic molecules, while coenzymes are organic molecules. (D)</p> Signup and view all the answers

Why do the required enzymes of stomach cells differ from those of fat storage cells?

<p>Different cells perform different functions. (A)</p> Signup and view all the answers

How does the concentration of an enzyme affect the rate of a reaction?

<p>Higher enzyme concentrations increase the reaction rate. (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of enzymes?

<p>They are permanently changed after catalyzing a reaction. (A)</p> Signup and view all the answers

Flashcards

Bioenergetics

The study of energy flow through living systems.

Metabolism

All chemical reactions in cells that consume or generate energy.

Spontaneous reactions

Chemical reactions that occur without needing energy input.

Adenosine triphosphate (ATP)

The primary energy currency of cells used for work.

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Photosynthesis

Process where plants convert CO2 into sugar using sunlight.

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Sugar metabolism

Metabolic processes that use and produce energy from sugars.

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Energy-storing molecules

Molecules like glucose that store energy for later use.

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Chemical reactions in cells

Stepwise reactions that build or break down molecules and manage energy.

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Enzymes

Proteins that catalyze chemical reactions by lowering activation energy.

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Substrates

Reactant molecules that enzymes bind to in a reaction.

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Activation Energy

The energy required to initiate a chemical reaction.

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Active Site

The specific region on an enzyme where the substrate binds.

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Induced Fit Model

A model describing how enzyme structure changes to fit substrates better.

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Enzyme-Substrate Complex

Temporary complex formed when an enzyme binds its substrate.

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Denaturation

Irreversible change in enzyme structure due to extreme conditions.

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Optimal Conditions

The ideal temperature and pH range for enzyme activity.

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Cofactors

Non-protein molecules that assist enzymes in catalysis.

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Enzyme Inhibition

Processes that decrease or block enzyme activity.

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Exergonic Reaction

A spontaneous chemical reaction that releases energy.

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Endergonic Reaction

A non-spontaneous reaction that requires energy input.

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Environmental Influences

Factors like temperature and pH that affect enzyme activity.

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Chemical Properties of R Groups

Unique characteristics of amino acids that affect enzyme activity.

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Cellular Demand Variability

Changes in enzyme requirements based on cell type and activity.

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Kinetic Energy

Energy associated with an object in motion.

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Potential Energy

Energy stored due to an object's position or condition.

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Chemical Energy

Potential energy stored within chemical bonds.

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Free Energy

Usable energy available after accounting for losses.

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Catalyst

Substance that speeds up a chemical reaction.

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Thermodynamics (Second Law)

All energy transfers involve losses in usable energy.

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Chemical Bonds

Connections between atoms in molecules that store potential energy.

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Molecular Level Potential Energy

Energy stored in the structure of molecules, like compressed springs.

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Energy Transformation

The process of changing energy from one form to another, like potential to kinetic.

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Energy Pathways

Processes like anabolic and catabolic pathways that manage energy in cells.

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Competitive inhibition

A process where an inhibitor competes with the substrate for the active site of an enzyme.

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Noncompetitive inhibition

An inhibition where an inhibitor binds to an allosteric site, preventing substrate binding at the active site.

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Allosteric inhibition

Inhibition that occurs when an inhibitor binds to an allosteric site, changing the enzyme's shape.

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Allosteric activation

When an allosteric activator binds to an enzyme, increasing its affinity for the substrate.

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Drug target

A molecule that is specifically targeted by a drug for action.

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Statins

A class of drugs that inhibit HMG-CoA reductase to lower cholesterol levels.

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HMG-CoA reductase

An enzyme that synthesizes cholesterol from lipids; targeted by statins.

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Feedback inhibition

Regulatory mechanism where the end product of a pathway inhibits an earlier step.

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ATP regulation

ATP serves as an allosteric regulator, affecting enzyme activity based on its levels.

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ADP as activator

ADP acts as a positive allosteric regulator, promoting ATP production.

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Enzyme conformation

The shape of an enzyme determined by its polypeptide structure, affecting its activity.

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Enzyme activity regulation

The process of modulating enzyme activity through various molecules including inhibitors and activators.

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Vitamins as coenzymes

Vitamins can act as direct coenzymes or precursors for coenzymes supporting enzymatic reactions.

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Metabolic Pathway

A series of chemical reactions converting a starting molecule through intermediates to a final product.

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Anabolic Pathways

Metabolic pathways that build larger molecules from smaller ones, requiring energy.

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Catabolic Pathways

Metabolic pathways that break down larger molecules into smaller ones, releasing energy.

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Thermodynamics

The study of energy transfer and its relationship with physical matter.

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Open System

A system that can exchange energy with its surroundings.

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Closed System

A system that cannot exchange energy with its surroundings.

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First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed or transferred.

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ATP

A molecule that stores and provides energy for cellular processes.

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Second Law of Thermodynamics

Energy transfers are never 100% efficient; some energy is lost as heat.

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Entropy

A measure of disorder in a system; higher entropy means more disorder.

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Usable Energy

Energy in a form that can be used to do work.

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Heat Energy

Energy transferred between systems that is not utilized for work.

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Energy Efficiency

The concept of minimizing energy losses in processes.

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Study Notes

Bioenergetics and Metabolism

  • Bioenergetics describes energy flow through living systems, such as cells. Cellular processes involve stepwise chemical reactions.
  • Some reactions are spontaneous (release energy), others require energy input.
  • Cells constantly obtain energy to power reactions, analogous to organisms consuming food.
  • Metabolism encompasses all cellular reactions, both energy-consuming and energy-producing.

Photosynthesis and Cellular Respiration

  • Sugar is a major energy source for living things, containing stored energy in its bonds.
  • Plants (photosynthetic organisms) produce sugars using sunlight to convert CO2 into sugar (like glucose). This is an energy-requiring process.
  • Photosynthesis: CO2 + Light Energy → Glucose + O2
  • Cellular respiration (reverse of photosynthesis) breaks down sugar molecules, releasing energy and consuming oxygen.
  • Cellular Respiration: Glucose + O2 → CO2 + Energy (ATP)

Metabolic Pathways

  • Metabolic pathways are sequences of chemical reactions that modify a starting molecule step-by-step to a final product.
  • Anabolic pathways build complex molecules from simpler ones, requiring energy input.
  • Catabolic pathways break down complex molecules into simpler ones, releasing energy.
  • Metabolism combines both anabolic and catabolic pathways.

Enzymes and Catalysts

  • Biochemical reactions are catalyzed by enzymes, proteins that speed up reactions.
  • Enzymes facilitate reactions by lowering activation energy, the initial energy needed for a reaction to proceed.
  • Enzyme structure determines specificity, meaning it can only catalyze particular types of reactions.
  • Enzymes are not used up in reactions, they can constantly be reused.

Thermodynamics and Energy

  • Thermodynamics studies energy and energy transfer.
  • A system is the matter of interest in energy transfer; surroundings are everything outside.
  • Open systems exchange energy with their surroundings (living things are open).
  • Closed systems do not exchange energy with their surroundings.
  • The first law of thermodynamics states that energy is conserved; it cannot be created or destroyed, only transformed.
  • Energy exists in various forms (e.g., light, heat, chemical).

Kinetic and Potential Energy

  • Kinetic energy is energy associated with motion.
  • Potential energy is energy stored due to position or structure.
  • Chemical bonds store potential energy that is released when broken.

Free Energy and Chemical Reactions

  • Free energy is usable energy available after accounting for unusable energy loss (often as heat).
  • Exergonic reactions release free energy (∆G is negative); they are spontaneous.
  • Endergonic reactions absorb free energy (∆G is positive); they are non-spontaneous.
  • Activation energy is the initial energy input needed for any reaction, even exergonic ones.

Enzyme Regulation

  • Enzyme activity is crucial for a cell's efficiency, as rates of reactions depends on activation energy lowering.
  • Enzyme activity is influenced by environmental factors (temperature, pH, salt concentration).
  • Enzymes can be regulated to turn enzyme activity on or off.
  • Competitive inhibition: an inhibitor competes with a substrate for the active site.
  • Non-competitive inhibition: an inhibitor binds elsewhere, but still blocks the active site.
  • Allosteric regulation: Inhibitor or activator binds to a site away from active site (allosteric site), changing the protein's conformation.

Drug Discovery

  • Enzymes are often drug targets in pharmaceutical development.
  • Drug targets are identified through research, and are evaluated to ensure positive effects and safety.
  • Understanding enzyme mechanisms and regulation can identify ideal drug targets.

Cofactors and Coenzymes

  • Cofactors are inorganic ions (e.g., iron, magnesium) that are needed for enzymatic function.
  • Coenzymes are organic molecules required for function.
  • Vitamins are often precursors of coenzymes.

Feedback Inhibition

  • Cells utilize products of their own reactions as regulators, slowing or halting further production.
  • Cells use feedback mechanisms to keep metabolic pathways in balance
  • ATP is an allosteric regulator of enzymes.

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