Energy Conversion in Living Systems

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Questions and Answers

Which of the following is a correct example of an endergonic reaction?

  • The release of energy from the breakdown of fats
  • The synthesis of proteins from amino acids (correct)
  • The diffusion of oxygen across a cell membrane
  • The breakdown of glucose to produce ATP

What is the primary function of ATP in living organisms?

  • To transport molecules across cell membranes
  • To provide energy for cellular processes (correct)
  • To store genetic information
  • To provide structural support for cells

Which of the following is NOT a characteristic of enzymes?

  • Enzymes are specific in their actions, binding to specific substrates.
  • Enzymes are proteins that act as catalysts.
  • Enzymes increase the activation energy of reactions. (correct)
  • Enzymes can be affected by temperature and pH.

Which of the following processes would be considered active transport?

<p>The movement of glucose into a cell against its concentration gradient (A)</p> Signup and view all the answers

How does feedback inhibition regulate metabolic pathways?

<p>By inhibiting an enzyme early in the pathway, preventing overproduction of the end product (A)</p> Signup and view all the answers

What is the relationship between cellular respiration and respiration?

<p>Respiration is the process of gas exchange, while cellular respiration is the process of ATP production. (D)</p> Signup and view all the answers

Which of the following is an example of a cofactor that assists an enzyme in its activity?

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

Why is it impossible for living organisms to directly convert heat energy into light energy?

<p>Heat energy is a form of random molecular motion, while light energy is a form of electromagnetic radiation, and living organisms lack the necessary mechanisms to convert between these forms. (C)</p> Signup and view all the answers

Flashcards

Chemical to Kinetic Energy

Conversion of chemical energy (e.g., glucose) into kinetic energy for movement.

First Law of Thermodynamics

Energy cannot be created or destroyed, only converted between forms.

Endergonic Reactions

Reactions that require energy input to proceed (e.g., glucose synthesis).

Exergonic Reactions

Reactions that release energy (e.g., glucose breakdown).

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ATP Production

ATP is made in mitochondria during cellular respiration by converting glucose.

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Cofactors vs Coenzymes

Cofactors are non-protein helpers (e.g., zinc), while coenzymes are organic helpers (often vitamins).

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Passive vs Active Transport

Passive transport (e.g., diffusion) does not use ATP; active transport requires ATP to move against gradients.

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Feedback Inhibition

The end product of a pathway stops an enzyme from working to prevent excess production.

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Study Notes

Energy Conversion in Living Systems

  • Chemical energy (like glucose) is converted to kinetic energy (motion), exemplified by sperm's movement.
  • Energy cannot be created or destroyed but can be converted.

Laws of Thermodynamics

  • First Law: Energy conservation; it's only transformed, not generated or destroyed.
  • Second Law: Energy transfers increase disorder (entropy) in the universe.
  • Third Law: As temperatures approach absolute zero, entropy approaches a minimum.

Impossible Energy Conversions

  • Heat cannot be directly converted to light within living systems. However, some organisms (like fireflies) can convert chemical energy to light.

Types of Metabolic Reactions

  • Endergonic: Reactions needing energy input; an example is glucose synthesis.
  • Exergonic: Reactions releasing energy; glucose breakdown is an example.

ATP and Energy

  • ATP (adenosine triphosphate) stores energy
  • ATP's phosphate bonds store the energy. A phosphate's removal releases energy (ATP → ADP + Pi + Energy).
  • ATP production in mitochondria through cellular respiration.

Enzyme Function

  • Enzymes are proteins that accelerate chemical reactions by lowering activation energy requirements.
  • Enzymes are specific to reactions; the active site matches the substrate.

Enzyme Helpers

  • Cofactors: Non-protein helpers (e.g., zinc) that assist enzymatic function.
  • Coenzymes: Organic helpers often derived from vitamins, important for enzyme function.

Transport Mechanisms

  • Passive Transport (e.g., diffusion): Does not require ATP and moves substances with the concentration gradient.
  • Active Transport: Uses ATP and moves substances against their concentration gradients.

Metabolic Pathways

  • Coupled reactions: An exergonic reaction driving an endergonic reaction.

Metabolic Regulation

  • Feedback Inhibition: The pathway's end product inhibits an earlier enzyme to prevent excess product buildup.

Factors Affecting Enzyme Activity

  • Temperature and pH: Optimal temperature and pH maximize enzyme activity.
  • Extreme conditions: Can denature enzymes, making them non-functional.

ATP Breakdown

  • ATP breaks down into ADP and inorganic phosphate (Pi), releasing needed energy.

Respiration vs. Cellular Respiration

  • Respiration: Gas exchange of oxygen absorption and carbon dioxide release.
  • Cellular Respiration: The process in the mitochondria breaking down glucose to produce ATP.

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