Bioenergetics and Metabolism Quiz

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Questions and Answers

What term is used to describe the flow of energy through living systems?

  • Energy Dynamics
  • Photochemistry
  • Bioenergetics (correct)
  • Metabolism

Which molecule serves as the primary energy currency of cells?

  • Glucose
  • Adenosine triphosphate (ATP) (correct)
  • Creatine phosphate
  • Nicotinamide adenine dinucleotide (NAD)

During photosynthesis, which of the following is produced as a waste product?

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

Which type of reaction requires energy input to proceed?

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

What do living organisms primarily consume sugars for?

<p>As a major energy source (A)</p> Signup and view all the answers

What is released during the cellular process that harvests the energy of sugar molecules?

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

What is the process of combining carbon dioxide and sunlight to form sugars called?

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

Which statement accurately describes metabolic pathways?

<p>They consist of stepwise chemical reactions involving energy transfer. (D)</p> Signup and view all the answers

Which metabolic pathway is responsible for building larger molecules from smaller ones?

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

What role do enzymes play in metabolic pathways?

<p>They catalyze and facilitate reactions. (D)</p> Signup and view all the answers

Which of the following statements is true about open systems?

<p>They allow energy transfer with the surroundings. (B)</p> Signup and view all the answers

According to the first law of thermodynamics, energy can be:

<p>Transformed but not destroyed. (C)</p> Signup and view all the answers

Which of the following correctly describes entropy?

<p>A measure of disorder and randomness. (A)</p> Signup and view all the answers

What happens to energy during cellular metabolic reactions?

<p>Some energy is lost as heat. (D)</p> Signup and view all the answers

What is the primary function of ATP in living cells?

<p>Storing and transferring energy for work. (C)</p> Signup and view all the answers

Which energy transformation occurs during photosynthesis?

<p>Light energy to chemical energy. (D)</p> Signup and view all the answers

What is a characteristic of a closed system?

<p>It cannot exchange energy with its surroundings. (C)</p> Signup and view all the answers

Energy is defined as:

<p>The ability to do work or create change. (B)</p> Signup and view all the answers

Which of the following best describes the second law of thermodynamics?

<p>Energy decreases in usable forms during transformations. (A)</p> Signup and view all the answers

What is the result of high entropy in a biological system?

<p>Less energy available; a state of low energy. (A)</p> Signup and view all the answers

Which type of energy is primarily used by living organisms for work?

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

How do living organisms maintain order within their systems?

<p>By consuming energy and transforming it. (B)</p> Signup and view all the answers

What is the primary role of enzymes in chemical reactions?

<p>To lower the activation energy required for reactions (B)</p> Signup and view all the answers

What is formed when an enzyme binds to its substrate?

<p>An enzyme-substrate complex (D)</p> Signup and view all the answers

What term describes the location on an enzyme where the substrate binds?

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

How do changes in environmental temperature affect enzyme activity?

<p>Optimal temperature increases reaction rates without denaturing enzymes (A)</p> Signup and view all the answers

What happens to enzymes at extremely high temperatures?

<p>They denature, losing their functional shape (D)</p> Signup and view all the answers

Which model describes the enzyme-substrate binding process as more dynamic?

<p>Induced fit model (A)</p> Signup and view all the answers

What property of amino acid side chains is crucial in creating the active site of an enzyme?

<p>They can be anything from weakly acidic to neutral (B)</p> Signup and view all the answers

How can enzymes participate in the chemical reaction they catalyze?

<p>By forming a temporary enzyme-substrate bond (A)</p> Signup and view all the answers

Why do different cells in the body require different enzymes?

<p>Cellular needs and conditions vary from cell to cell (B)</p> Signup and view all the answers

What effect do inhibitors have on enzyme activity?

<p>They can block substrate binding and reduce activity (A)</p> Signup and view all the answers

What does the enzyme-substrate complex do to facilitate a biochemical reaction?

<p>Facilitates a precise structural alignment of substrates (C)</p> Signup and view all the answers

What is a consequence of enzyme denaturation?

<p>Permanent change in enzyme function (B)</p> Signup and view all the answers

What are cofactors and coenzymes in relation to enzyme action?

<p>They are additional molecules that assist enzyme function (D)</p> Signup and view all the answers

Which of the following statements is true about enzyme kinetics?

<p>The rate of reaction increases with enzyme concentration until saturation (D)</p> Signup and view all the answers

What characterizes competitive inhibition in enzyme activity?

<p>An inhibitor binds to the active site exclusively. (A)</p> Signup and view all the answers

How does noncompetitive inhibition differ from competitive inhibition?

<p>It alters the active site by binding to a different site on the enzyme. (D)</p> Signup and view all the answers

What type of molecule can act as an allosteric inhibitor?

<p>A non-substrate molecule that induces a conformational change. (D)</p> Signup and view all the answers

Which of the following statements about allosteric enzymes is correct?

<p>They exhibit changes in activity through conformational changes. (D)</p> Signup and view all the answers

What role do coenzymes serve in enzyme functions?

<p>They help enzymes perform functions without being changed themselves. (A)</p> Signup and view all the answers

What is feedback inhibition?

<p>The regulation of enzyme activity by its own products. (A)</p> Signup and view all the answers

What is an example of an allosteric activator's function?

<p>It induces a conformational change that enhances substrate binding. (D)</p> Signup and view all the answers

Which of the following statements about statins is correct?

<p>They inhibit the enzyme HMG-CoA reductase, lowering cholesterol levels. (C)</p> Signup and view all the answers

What do cofactors and coenzymes have in common?

<p>Both enhance the function of enzymes during reactions. (C)</p> Signup and view all the answers

ATP serves as what type of regulator in metabolic pathways?

<p>An allosteric inhibitor preventing further ATP production. (B)</p> Signup and view all the answers

In the context of enzyme activity, what does an allosteric inhibitor do?

<p>It binds at a location distinct from the active site to reduce enzyme activity. (D)</p> Signup and view all the answers

Which molecule is an example of a direct coenzyme involved in enzymatic reactions?

<p>Vitamin C. (C)</p> Signup and view all the answers

What is the main challenge in drug discovery related to drug targets?

<p>Identifying the specific cellular reactions associated with disease. (B)</p> Signup and view all the answers

What is the primary action of acetaminophen in the body?

<p>It inhibits the enzyme cyclooxygenase, providing relief from pain. (D)</p> Signup and view all the answers

Which of the following statements correctly describes the relationship between kinetic and potential energy in a pendulum?

<p>Kinetic energy is highest when the pendulum is at its lowest point. Potential energy is highest at the highest point. (A)</p> Signup and view all the answers

How are the energies associated with chemical reactions quantified and expressed?

<p>By calculating the change in free energy (∆G) of the reaction. (C)</p> Signup and view all the answers

What is the role of activation energy in chemical reactions?

<p>Activation energy is the minimum energy required for a reaction to proceed. (A)</p> Signup and view all the answers

Which of the following is an example of an exergonic reaction?

<p>The burning of wood. (D)</p> Signup and view all the answers

What is the primary function of enzymes in biological systems?

<p>To increase the rate of chemical reactions by lowering activation energy. (C)</p> Signup and view all the answers

Which of the following statements about endergonic reactions is true?

<p>Endergonic reactions require an input of energy to occur. (C)</p> Signup and view all the answers

Identify the type of energy stored in the bonds of food molecules.

<p>Potential energy (C)</p> Signup and view all the answers

Which of the following processes is an example of an endergonic reaction?

<p>The synthesis of proteins from amino acids. (C)</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>The potential energy is converted to kinetic energy. (B)</p> Signup and view all the answers

A negative change in free energy (∆G) indicates which type of reaction?

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

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

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

Which of the following factors does NOT influence the activation energy of a chemical reaction?

<p>Change in free energy (∆G) (B)</p> Signup and view all the answers

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

<p>It dictates that energy transfers always result in some energy loss as heat. (A)</p> Signup and view all the answers

Which of the following statements best describes the relationship between spontaneous reactions and the rate of reaction?

<p>Spontaneous reactions can occur quickly or slowly depending on the activation energy. (D)</p> Signup and view all the answers

Which of these statements is true about the movement of molecules and kinetic energy?

<p>As molecular movement increases, kinetic energy increases. (B)</p> Signup and view all the answers

What is the main reason why life requires the presence of enzymes to catalyze biochemical reactions?

<p>To speed up the rate of reaction at physiological temperatures. (D)</p> Signup and view all the answers

Flashcards

Bioenergetics

The study of energy flow in living systems, particularly in cells.

Metabolism

All chemical reactions in a cell that consume or generate energy.

ATP

Adenosine triphosphate, the primary energy currency of cells.

Photosynthesis

Process by which plants convert CO2 into sugar using sunlight energy.

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Energy-storing molecules

Molecules like glucose that store energy for later use.

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Light reactions

Part of photosynthesis that converts sunlight into energy stored in ATP.

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Metabolic pathways

Series of chemical reactions in metabolism, involving building or breaking down substances.

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Respiration

Process of breaking down sugars in cells, releasing energy and producing CO2.

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Anabolic pathways

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

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Enzymes

Proteins that catalyze (speed up) chemical reactions in metabolic pathways.

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Thermodynamics

The study of energy and energy transfer involving 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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Energy transformations

Processes where energy changes from one form to another.

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Second law of thermodynamics

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

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Entropy

A measure of disorder or randomness in a system.

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Systems in biology

Biological organisms are open systems that exchange energy with surroundings.

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Chemical energy

Energy stored in the bonds of chemical compounds, such as sugars and fats.

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Kinetic Energy

The energy an object possesses due to its motion.

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Potential Energy

Stored energy based on an object's position or configuration.

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Exergonic Reactions

Reactions that release free energy with a negative ∆G.

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Endergonic Reactions

Reactions that absorb energy and have a positive ∆G.

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Activation Energy

The initial energy needed to start a chemical reaction.

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Free Energy (G)

Usable energy in a system after accounting for losses.

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Spontaneous Reactions

Reactions that occur without external energy input; can be slow.

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Catalyst

A substance that speeds up a chemical reaction without being consumed.

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Molecular Potential Energy

Potential energy associated with the structure of molecules and atom bonds.

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Pendulum Energy Transition

The shift between potential and kinetic energy in a swinging pendulum.

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∆G (Delta G)

The change in free energy during a chemical reaction.

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Energy in Chemical Bonds

Potential energy stored within the bonds of food molecules.

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Enzyme Function

Enzymes reduce activation energy and speed up reactions.

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Substrates

The reactant molecules that enzymes bind to.

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Active Site

The specific region on the enzyme where substrates bind.

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Induced Fit Model

Enzyme and substrate adjust to fit together during binding.

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Denaturation

The irreversible change in enzyme's shape due to extreme conditions.

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Optimal Conditions

Specific temperature and pH range where enzymes function best.

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Enzyme-Substrate Complex

The temporary structure formed when an enzyme binds its substrate.

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Cofactors

Non-protein molecules that assist enzymes in their functions.

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Inhibitors

Molecules that decrease enzyme activity by blocking substrates.

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Metabolic Regulation

The process of controlling enzyme activity based on cell needs.

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Enzyme Specificity

The unique ability of an enzyme to bind to specific substrates.

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Biochemical Reactions

Processes that involve changes in chemical bonds, typically involving enzymes.

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pH Influence

The effect of acidity or basicity on enzyme activity.

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Temperature Influence

Impact of temperature on the rate of enzymatic reactions.

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Competitive Inhibition

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

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Noncompetitive Inhibition

Inhibition where an inhibitor binds to a site other than the active site, preventing substrate binding.

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Allosteric Site

A site on an enzyme where an inhibitor or activator binds, distinct from the active site.

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Allosteric Inhibition

When binding of an inhibitor at an allosteric site decreases enzyme activity.

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Allosteric Activators

Molecules that bind to allosteric sites and increase enzyme activity.

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Drug Target

A specific molecule that a drug aims to interact with to produce a therapeutic effect.

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Feedback Inhibition

Regulation where the product of a reaction inhibits its own production by inhibiting the enzyme.

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ATP as Regulator

ATP can act as an allosteric regulator, inhibiting some enzymes when abundant.

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ADP as Activator

ADP can act as an allosteric activator for some enzymes, promoting ATP production.

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Statins

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

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Acetaminophen Mechanism

Acetaminophen inhibits cyclooxygenase, reducing pain and inflammation.

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Enzyme Regulation

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

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Enzyme Conformational Change

A change in enzyme structure that affects function, usually induced by binding of other molecules.

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Study Notes

Bioenergetics and Metabolism

  • Bioenergetics describes energy flow through living systems (cells).
  • Cellular processes involve stepwise chemical reactions.
  • Some reactions release energy (spontaneous), others require energy input.
  • Cells constantly obtain energy to power reactions—metabolism.
  • Metabolism includes all chemical reactions in a cell.

Sugar Metabolism

  • Sugar is a major energy source for living things.
  • Photosynthesis produces sugars from CO2 and sunlight.
    • Photosynthesis equation: CO2 + sunlight → sugar + O2.
  • Plants use sunlight energy to create glucose (C6H12O6).
  • Adenosine triphosphate (ATP) is the main energy currency of cells.
    • ATP is used for immediate cell work.
  • Glucose is broken down to release energy.

Metabolic Pathways

  • Metabolic pathways are series of chemical reactions.
  • Anabolic pathways synthesize complex molecules (require energy).
  • Catabolic pathways break down complex molecules (release energy).
  • Anabolism and Catabolism compose metabolism.
  • Enzymes catalyze each reaction step in metabolic pathways.

Thermodynamics

  • Thermodynamics studies energy and energy transfer in physical systems.
  • A system is the matter involved in an energy transfer, and surroundings are the external environment.
  • Biological systems are open systems—exchange energy with surroundings.
  • The first law of thermodynamics states that energy is conserved.
  • Energy can be transferred or transformed but not created or destroyed.
    • Examples of energy transformation: light bulb (electrical to light/heat), gas stove (chemical to heat).

Energy Forms and Types

  • Energy is the ability to do work or create change. Energy exists in different forms (electrical, light, heat, etc.).
  • Kinetic energy is energy of motion (e.g., a moving object).
  • Potential energy is stored energy (e.g., a raised object).
  • Chemical energy is potential energy stored in chemical bonds.
  • Cellular processes transform energy for work.

Free Energy and Chemical Reactions

  • Free energy is usable energy after energy losses are accounted for.
  • Changing free energy is denoted as ∆G.
  • Exergonic reactions release free energy (∆G is negative), and are spontaneous (but not necessarily fast).
  • Endergonic reactions absorb free energy (∆G is positive), and are non-spontaneous.
  • Activation energy is the initial energy needed for any chemical reactions.

Enzymes

  • Enzymes are biological catalysts (proteins).
  • Lower activation energy to speed up reactions, without changing ∆G.
  • Reactants that bind to enzymes are substrates.
  • The active site is the substrate-binding region on an enzyme.
  • Enzyme function is affected by temperature, pH, and salt concentrations.
  • The induced fit model describes a more dynamic interaction between enzyme and substrates.

Enzyme Regulation

  • Enzyme activity is controlled by various molecules in the cell.
  • Competitive inhibition blocks the active site.
  • Noncompetitive inhibition binds to another enzyme region (allosteric site).
  • Allosteric inhibition changes enzyme conformation.
  • Allosteric activators increase catalytic efficiency.

Metabolic Regulation

  • Cells use feedback inhibition wherein pathways products regulate their own production process.
  • Examples of feedback inhibition: amino acids, nucleotides and ATP regulation.
  • The ratio of ATP to ADP influences enzyme activity.

Drug Discovery

  • Drugs influence enzyme function for therapeutic purposes.
  • Drug targets are enzymes involved in disease processes.
  • Statins are HMG-CoA reductase inhibitors to lower cholesterol
  • Acetaminophen inhibits cyclooxygenase (pain relief)
  • Enzymes need cofactors (inorganic ions) and coenzymes (organic molecules—derived from vitamins) for optimal function.
  • Vitamins often serve as precursers or are directly coenzymes for enzymatic pathways

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