Metabolic Pathways and Thermodynamics
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Questions and Answers

Which of the following best describes potential energy?

  • Energy in motion
  • Energy lost during reaction
  • Energy stored in an object (correct)
  • Energy released during oxidation

In a redox reaction, oxidation always involves gaining electrons.

False (B)

What is the source of energy for the biosphere?

Sunlight

The equation for Gibbs free energy is G = H - ___S.

<p>TS</p> Signup and view all the answers

What is the primary role of ATP in energy metabolism?

<p>As an intermediate that releases energy on demand (D)</p> Signup and view all the answers

Match the terms with their correct definitions:

<p>Kinetic Energy = Energy an object possesses due to its motion Potential Energy = Energy stored in an object Exergonic Reaction = Reaction that releases energy Endergonic Reaction = Reaction that absorbs energy</p> Signup and view all the answers

Enzymes can catalyze multiple types of reactions.

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

What happens when ∆G < 0 in a chemical reaction?

<p>The reaction releases energy (C)</p> Signup and view all the answers

What mechanisms allow enzymes to bind to substrates?

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

Catalysts increase the activation energy required for reactions.

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

What does the term 'entropy' refer to in the context of energy transformations?

<p>Increase in disorder or randomness</p> Signup and view all the answers

ATP includes three ______ groups that repel each other.

<p>phosphate</p> Signup and view all the answers

Match the following types of reactions with their descriptions:

<p>Anabolic reactions = Build up molecules and expend energy Catabolic reactions = Break down molecules and harvest energy Oxidation-dehydrogenation reactions = Transfer electrons from oxidized molecules to electron carriers Metabolic pathways = Sequences of chemical reactions where products serve as substrates for subsequent reactions</p> Signup and view all the answers

Which factor does NOT influence the rate of enzyme-catalyzed reactions?

<p>Molecular weight of the enzyme (B)</p> Signup and view all the answers

Metabolic pathways are unique to each individual cell.

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

Name the two main types of metabolic reactions.

<p>Anabolic and catabolic reactions</p> Signup and view all the answers

Flashcards

Kinetic Energy

Energy of motion

Potential Energy

Stored energy of position

Source of biosphere energy

Sunlight

Redox Reaction

Electron transfer reaction; one atom loses electrons; the other gains electrons

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First Law of Thermodynamics

Energy can't be created or destroyed, only transformed.

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Exergonic Reaction

Releases energy; spontaneous reaction

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Endergonic Reaction

Absorbs energy; non-spontaneous reaction

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Enzyme Catalyst

Speeds up reactions by lowering activation energy

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High-energy bonds in ATP

The covalent bonds connecting phosphate groups in ATP are unstable, requiring low activation energy for hydrolysis and releasing a significant amount of energy when broken.

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Specificity of enzymes

Enzymes are highly specific, catalyzing only one particular reaction.

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Induced fit model

The enzyme's active site changes shape to precisely fit the substrate, resulting in a tighter binding.

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Anabolic reactions

Reactions that use energy to build larger molecules.

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Catabolic reactions

Reactions that release energy by breaking down molecules.

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Metabolic pathway

A series of chemical reactions where products from one reaction become substrates for the next.

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Metabolism is evolutionary

Major metabolic pathways are universal across cells, indicating a shared evolutionary origin.

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Oxidation-dehydrogenation

Reactions involving electron transfer, often coupled with proton transfer in biological systems.

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Study Notes

Metabolic Pathways

  • Kinetic vs. Potential Energy: Kinetic energy is energy of motion; potential energy is stored energy due to position.

  • Biosphere Energy Source: Sunlight.

  • Redox Reactions: Paired reactions where electrons are transferred. Oxidation is loss of electrons; reduction is gain of electrons. Reduced forms have more energy.

Thermodynamics

  • First Law: Energy cannot be created or destroyed.

  • Second Law: Energy transformation isn't perfectly efficient, increasing system entropy.

  • Free Energy: Energy available to do work (G = H - TS). ∆G < 0 = exergonic, spontaneous; ∆G > 0 = endergonic, not spontaneous; ∆G = 0 = no net change.

  • Catalysts & Reaction Rates: Catalysts like enzymes decrease activation energy (energy needed to start a reaction), speeding the reaction.

ATP

  • Short-Term Energy Storage: ATP captures energy from exergonic reactions, acting as an intermediate to be hydrolyzed and used on demand.

  • High-Energy Bonds: Phosphate bonds in ATP are unstable, releasing energy when broken. Further stabilization by water release more energy

Enzymes

  • Specificity: Enzymes are highly specific to one reaction.

  • Enzyme-Substrate Binding: Induced fit model: enzyme changes shape slightly to bind tightly with its substrate.

  • Factors Affecting Enzyme Rate: Temperature, pH, regulators (inhibitors or activators).

Metabolism

  • Anabolic vs. Catabolic Reactions: Anabolic reactions build molecules, consuming energy; catabolic reactions break down molecules, releasing energy.

  • Metabolic Pathways: Sequences of reactions where products of one reaction are substrates for the next.

  • Evolutionary Origins: Most metabolic pathways are shared among cells—common carbon and energy pathways converge.

Oxidation-Dehydrogenation

  • Oxidation-dehydrogenation reactions are common in redox reactions, where electrons are transferred to electron carriers along with protons.

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Description

Explore the essential concepts of metabolic pathways and thermodynamics in this quiz. Test your understanding of kinetic and potential energy, redox reactions, and the laws of thermodynamics. Learn about ATP's role in energy storage and transformation.

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