Bioenergetics SBP3411 Quiz
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Questions and Answers

What role do enzymes play in chemical reactions within cells?

  • They bond with products to deactivate them.
  • They increase the activation energy required for reactions.
  • They act as substrates in the reactions.
  • They lower the activation energy needed for the reactions. (correct)

What is required for an enzyme to effectively facilitate a reaction?

  • Prolonged interactions with substrates (correct)
  • Formation of allosteric inhibitors
  • High temperatures and pressures
  • Excessive substrate concentration

Which of the following statements about enzymes is true?

  • Enzymes can only catalyze one type of reaction.
  • Enzymes are permanently altered after a reaction.
  • Enzymes are highly selective and produce only required compounds. (correct)
  • Enzymes eliminate the need for substrates.

What characterizes activated carriers in biological systems?

<p>They store energy temporarily in covalent bonds. (A)</p> Signup and view all the answers

Which activated carrier is considered the most important for energy transfer?

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

What does Delta G (ΔG) signify in a chemical reaction?

<p>The amount of disorder caused by the reaction (D)</p> Signup and view all the answers

Which statement best describes the 2nd law of thermodynamics as it relates to chemical reactions?

<p>Chemical reactions must increase the disorder of the universe. (A)</p> Signup and view all the answers

What is the role of activation energy in spontaneous reactions?

<p>It is the energy required to reach a more stable state from a stable state. (C)</p> Signup and view all the answers

Which of the following pathways is correctly associated with biosynthesis?

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

What are neurotransmission and potential gradients primarily influenced by?

<p>The selective movement of ions and compounds (A)</p> Signup and view all the answers

What is the primary role of enzymes in cellular processes?

<p>To drive intracellular chemical reactions. (B)</p> Signup and view all the answers

Which of the following best describes activated carriers?

<p>Molecules that capture and transfer energy. (A)</p> Signup and view all the answers

What occurs during ATP hydrolysis?

<p>ATP is converted to ADP and inorganic phosphate, releasing energy. (B)</p> Signup and view all the answers

How do cells primarily obtain the energy needed for metabolic processes?

<p>By extracting energy from the oxidation of organic molecules. (A)</p> Signup and view all the answers

What does reaction coupling in metabolic processes involve?

<p>Linking favorable reactions to unfavorable ones to drive processes. (C)</p> Signup and view all the answers

According to the 1st Law of thermodynamics, what can be stated about energy?

<p>Energy can only be transformed from one form to another. (C)</p> Signup and view all the answers

Which types of energy are involved in cellular metabolism?

<p>Mechanical, chemical, and electric energy. (D)</p> Signup and view all the answers

Which of the following energy types is generated during muscle contraction?

<p>Mechanical energy for physical activity. (A)</p> Signup and view all the answers

What role does ATP primarily serve in cellular processes?

<p>It serves as the principal activated carrier of energy. (C)</p> Signup and view all the answers

What drives the hydrolysis of ATP?

<p>The stabilization of released inorganic phosphate by hydrogen bonding with water. (C)</p> Signup and view all the answers

What kind of reaction is phosphorylation considered to be in relation to ATP?

<p>It is a condensation reaction driven by energy release. (D)</p> Signup and view all the answers

What facilitates the synthesis of ATP from ADP?

<p>Phosphorylation reactions coupled with other energetic processes. (C)</p> Signup and view all the answers

Which factor contributes to the high-energy nature of ATP?

<p>The unfavorable repulsion between adjacent negative charges within the structure. (C)</p> Signup and view all the answers

Which cellular processes are regulated through phosphorylation reactions facilitated by ATP?

<p>Protein activity and metabolic pathways. (D)</p> Signup and view all the answers

What is the change in Gibbs free energy (ΔG) for ATP hydrolysis and its significance?

<p>Large negative change, indicating a spontaneous reaction. (A)</p> Signup and view all the answers

Which statement about the release of inorganic phosphate (Pi) during ATP hydrolysis is true?

<p>It is stabilized by hydrogen bonds formed with water. (C)</p> Signup and view all the answers

What is the energy yield from the alternative route for ATP hydrolysis?

<p>-109 kJ/mole (B)</p> Signup and view all the answers

What role does high NADPH concentration serve in metabolic pathways?

<p>Reducing agent for anabolic reactions (D)</p> Signup and view all the answers

Which of the following correctly describes the structural difference between NADPH and NADH?

<p>NADPH contains an additional phosphate group compared to NADH (B)</p> Signup and view all the answers

What is typically necessary for biosynthetic reactions that involve Acetyl Coenzyme A?

<p>Transfer of chemical groups like methyl or carboxyl (C)</p> Signup and view all the answers

Under what conditions is NAD+ considered to be an oxidizing agent?

<p>When it is in high concentration (C)</p> Signup and view all the answers

What type of bond is particularly associated with Acetyl Coenzyme A that aids in recognition by enzymes?

<p>Thioester bond (C)</p> Signup and view all the answers

How does NADPH stabilize the electron arrangement in reactions?

<p>By donating a hydride ion to other compounds (A)</p> Signup and view all the answers

Which reaction would most likely utilize the energy derived from the common route of ATP hydrolysis?

<p>Polynucleotide synthesis (C)</p> Signup and view all the answers

Flashcards

Source of cellular energy

Cells obtain energy through the oxidation of organic molecules, like in muscle contraction or photosynthesis.

Intracellular reactions

Many processes inside cells need energy input, like building or breaking down molecules.

Energetically favorable reactions

Reactions that release energy; they happen spontaneously.

Energetically unfavorable reactions

Reactions that require energy input to happen; they don't occur spontaneously.

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Reaction coupling

Linking an energy-releasing reaction to an energy-requiring reaction to drive the latter.

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Activated carriers

Molecules that carry chemical energy around inside cells.

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First Law of Thermodynamics

Energy can neither be created nor destroyed, just transformed.

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Kinetic Energy

Energy of motion, like the energy in moving molecules.

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Potential Gradient

A difference in concentration of a substance across a membrane, creating a driving force for movement.

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Electric Gradient

A difference in electrical charge across a membrane, creating a driving force for movement of charged particles.

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2nd Law of Thermodynamics

A chemical reaction can only occur if it increases the overall disorder of the universe, resulting in a loss of free energy.

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Anabolic Pathway

A metabolic pathway that builds complex molecules from simpler ones, requiring energy input.

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Catabolic Pathway

A metabolic pathway that breaks down complex molecules into simpler ones, releasing energy.

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Activation Energy (EA)

The minimum amount of energy required for a molecule to undergo a chemical reaction, transforming into a lower energy state.

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Enzymes: Biological Catalysts

Enzymes are biological catalysts that speed up chemical reactions within cells by lowering the activation energy required for the reaction to occur.

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Enzyme Specificity

Enzymes are highly specific, meaning they only catalyze specific reactions involving specific molecules called substrates.

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Activated Carriers: Small molecules that store chemical energy.

Tiny molecules that store energy temporarily in chemical bonds, allowing them to easily transport energy where needed in the cell.

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ATP: The Cell's Energy Currency

ATP is a key activated carrier involved in energy transfer within cells. It stores energy in its phosphate bonds, which can be broken to release energy for cellular processes.

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What is ATP's role in cells?

ATP serves as the primary activated carrier, providing both energy and chemical groups for biosynthetic reactions.

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What makes ATP a high-energy molecule?

ATP stores energy in its unstable phosphate bonds, easily broken down to release energy.

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How is ATP synthesized?

ATP is synthesized by adding a phosphate group to ADP, requiring energy input through coupling with favorable reactions.

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What is ATP hydrolysis?

ATP hydrolysis is the breakdown of ATP into ADP and a phosphate group, releasing energy.

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What drives phosphorylation reactions?

ATP hydrolysis provides the energy to drive phosphorylation reactions, which are essential for various cellular processes.

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How does phosphorylation regulate cellular processes?

Phosphorylation can activate or deactivate proteins, regulate metabolic pathways, and participate in intracellular signaling.

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What is meant by 'reaction coupling'?

Coupling refers to linking an energy-releasing reaction (e.g., ATP hydrolysis) to an energy-requiring reaction to drive the latter.

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What are the characteristics of activated carriers?

Activated carriers are molecules like ATP that carry chemical energy and readily transferable groups for various cellular processes.

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ATP Hydrolysis Alternative Route

A metabolic pathway that produces more energy ( -109 kJ/mole) than the common route (-46 to -54 kJ/mole) through ATP hydrolysis.

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NADPH and NADH: Carriers

Both NADPH and NADH carry energy in the form of a hydride ion (H-) and are involved in different metabolic reactions.

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NADPH vs. NADH: Role

NADPH is a reducing agent used in anabolic reactions (building up), while NADH is an oxidizing agent used in catabolic reactions (breaking down).

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Acetyl Coenzyme A: Chemical Groups

Acetyl CoA carries chemical groups like acetyl, methyl, carboxyl, and glucose, needed for various biosynthetic reactions.

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Thioester Bond in Acetyl CoA

The special bond in Acetyl CoA that stores high energy, similar to the phosphate bond in ATP.

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Importance of Coenzymes

Coenzymes like NADPH and Acetyl CoA play crucial roles in metabolic reactions and are essential for life.

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Activated Carriers: Energy Transporters

Activated carriers like NADH and NADPH transport high-energy electrons for metabolic reactions.

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Metabolic Reactions Need Energy?

Many biosynthetic reactions require energy input to build molecules, while catabolic reactions release energy from breaking down molecules.

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Study Notes

Course Information

  • Course code: SBP3411
  • Course name: Bioenergetics
  • Instructor: Dr. Hanis H. Harith
  • Department: Biomedical Science, UPM
  • Email: [email protected]

Learning Outcomes

  • Describe how cells obtain energy for most cellular processes
  • Explain the role of enzymes in driving intracellular chemical reactions
  • Describe the function of activated carriers and identify high-energy bonds in selected activated carriers
  • Describe ATP synthesis and hydrolysis

Lecture Outline

  • Source of energy for cellular metabolism
  • Energetically favorable vs unfavorable reactions
  • Reaction coupling
  • Activated carriers

Most Intracellular Reactions Require Energy Input

  • Catabolic pathways break down food molecules, releasing energy
  • Anabolic pathways use energy to build complex molecules
  • Examples of synthesis versus breakdown of macromolecules include condensation and hydrolysis

Sources of Energy for Cellular Metabolism

  • Kinetic energy (e.g., thermal, radiant, mechanical, electric)
  • Potential energy (e.g., chemical, concentration gradient)

Cells Convert Energy to Different Forms

  • First Law of Thermodynamics: Energy cannot be created or destroyed, only transformed
  • Cells extract energy from the oxidation of organic molecules
  • Energy is stored in covalent bonds

Energetically Favorable vs Unfavorable Reactions

  • Second Law of Thermodynamics: Reactions occur only if they increase the disorder of the universe (loss of free energy)
  • ΔG (Gibbs Free Energy) measures the amount of disorder
  • Positive ΔG = unfavorable reaction (needs energy input)
  • Negative ΔG = favorable reaction (releases energy)
  • Reaction coupling: Coupling an unfavorable reaction to a favorable reaction makes the overall reaction favorable

Activation Energy is Required to Initiate Spontaneous Reactions

  • Molecules in cells are relatively stable
  • Spontaneous reaction needs activation energy to overcome stable states
  • Enzymes lower the activation energy, speeding up reactions
  • Activation energy lowers the barrier for reactions to occur

Enzymes Lower Activation Energy

  • Biological catalysts that speed up chemical reactions
  • Prolonged interaction between enzyme and substrates (multiple non-covalent bonds)
  • Substrate binding to enzyme rearranges electrons
  • Highly selective; only specific compounds are required.
  • Enzymes remain unchanged and can be reused

Enzymes Can Create Biological Order by Reaction Coupling

  • Coupled reactions: Reactions that share intermediate
  • Unfavorable reaction coupled to favorable reaction.
  • Change the overall ΔG to be favorable

Activated Carriers

  • Small organic molecules that store energy temporarily in covalent bonds
  • Diffuse rapidly; transport energy where needed
  • Examples: ATP, NADH, NADPH, acetyl CoA
  • Energy stored in easily exchangeable forms

ATP: The Principal Activated Carrier in Cells

  • ATP synthesis involves phosphorylation of ADP and requires reaction coupling
  • ATP hydrolysis releases energy that drives reactions.
  • There is unfavorable repulsion between adjacent -ve charges within ATP molecule

ATP Hydrolysis Drives Phosphorylation Reactions

  • ATP transfers a phosphate group to another molecule (phosphorylation)
  • Hydrolysis of ATP drives unfavorable reactions

Alternative Route for ATP Hydrolysis

  • Alternative route produces more energy to drive demanding reactions

NADPH and NADH: Activated Carriers of Electrons

  • Carry energy in the form of a hydride ion (H-)
  • Donate H- to achieve a more stable arrangement of electrons
  • Structural differences determine roles in metabolic pathways

Acetyl Coenzyme A

  • Contains a large organic portion that facilitates recognition by specific enzymes
  • Involved in metabolic processes (e.g., citric acid cycle, lipid synthesis)

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SBP3411 Bioenergetics 2023 PDF

Description

Test your understanding of bioenergetics concepts, including how cells obtain energy, the role of enzymes, and ATP synthesis. This quiz will cover key topics such as reaction coupling and activated carriers. Prepare to demonstrate your knowledge on cellular metabolism in relation to both catabolic and anabolic pathways.

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