Bioenergetics and Free Energy Change
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Questions and Answers

What is the primary structural feature of glycogen?

  • Linear chain only
  • Unbranched with a central protein
  • Completely symmetrical
  • Branched-chain (correct)

The liver only uses glycogen for its own energy needs.

False (B)

What molecule needs to be activated by UDP before being integrated into glycogen?

Glucose 1-P

The synthesis of ribose 5-phosphate is a product of the __________ pathway.

<p>Pentose Phosphate</p> Signup and view all the answers

Which of the following is a function of glycogen in skeletal muscle?

<p>Serves as a local and fast resource for ATP (B)</p> Signup and view all the answers

Match the following components with their associated functions:

<p>Glucose 6-P = Intermediate for glycolysis Ribulose 5-P = Nucleotide synthesis NADPH = Reducing agent in biosynthesis UDP-glucose = Activated form of glucose for glycogen synthesis</p> Signup and view all the answers

Which type of reaction in the Pentose Phosphate Pathway is irreversible?

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

What is the center protein around which glycogen is built?

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

What is the primary function of NADH and FADH2 in the electron transport chain?

<p>To donate electrons (D)</p> Signup and view all the answers

One molecule of NADH yields approximately 2.5 ATP when fully oxidized.

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

What is the total ATP yield from one mole of glucose after glycolysis and the TCA cycle?

<p>36 or 38 ATP</p> Signup and view all the answers

The conversion of pyruvate to acetyl-CoA occurs during the ______ stage.

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

Match the following pathways with their descriptions:

<p>Glycolysis = Breakdown of glucose to pyruvate Gluconeogenesis = Synthesis of glucose from non-carbohydrate sources Pentose Phosphate Pathway = Generating ribose-5-phosphate for nucleotide synthesis Glycogen Degradation = Mobilization of glucose from stored glycogen</p> Signup and view all the answers

Which shuttle converts NADH into FADH2 within the mitochondria?

<p>Glycerol 3-phosphate Shuttle (C)</p> Signup and view all the answers

The body relies solely on dietary intake for a stable blood glucose level.

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

Name one of the end products of glycolysis.

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

After glycolysis, pyruvate is converted to ______ before entering the TCA cycle.

<p>acetyl-CoA</p> Signup and view all the answers

From where can blood glucose be obtained?

<p>Diet, gluconeogenesis, and glycogen degradation (B)</p> Signup and view all the answers

What is the main purpose of bioenergetics?

<p>To transfer and utilize energy in biological systems (B)</p> Signup and view all the answers

A negative ΔG indicates a spontaneous reaction.

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

What are the two main types of ATP production?

<p>Substrate-level phosphorylation and oxidative phosphorylation.</p> Signup and view all the answers

The __________ cycle is also known as the Krebs cycle.

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

Match the following metabolic pathways with their functions:

<p>Glycolysis = Energy production and pyruvate formation Glycogenesis = Synthesis of glycogen from glucose Glycogenolysis = Breakdown of glycogen to glucose TCA Cycle = Harvesting high-energy electrons</p> Signup and view all the answers

Which molecule is commonly referred to as the energy currency of the cell?

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

The electron transport chain involves the reduction of oxygen to water.

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

What is the end product of glycolysis?

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

NADH and FADH2 serve as electron __________ in ATP synthesis.

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

Match the following ATP production methods with their descriptions:

<p>Substrate-level phosphorylation = Direct synthesis of ATP from ADP Oxidative phosphorylation = ATP production coupled with electron transport Fermentation = Anaerobic process that regenerates NAD+</p> Signup and view all the answers

Which pathway provides intermediates for the synthesis of amino acids, lipids, and carbohydrates?

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

Glycogenesis is the process of breaking down glycogen into glucose.

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

What happens to pyruvate in the presence of oxygen?

<p>It is converted to Acetyl-CoA and enters the TCA cycle.</p> Signup and view all the answers

The __________ phosphate pathway produces ribose-5-phosphate.

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

Match each molecule with its energy contribution:

<p>ATP = Immediate energy currency ADP = Lower energy state than ATP NADH = High-energy electron carrier FADH2 = Another high-energy electron carrier</p> Signup and view all the answers

Flashcards

Cellular Respiration

The process by which the cell generates energy by oxidizing glucose, leading to the production of ATP.

ATP (Adenosine Triphosphate)

A high-energy molecule that provides energy for most cellular processes.

Electron Transport Chain (ETC)

A series of protein complexes embedded in the inner mitochondrial membrane that transfers electrons to create a proton gradient, driving ATP synthesis.

Oxidative Phosphorylation

The process by which ATP is produced from ADP and inorganic phosphate using energy from the proton gradient generated by the ETC.

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Glycolysis

The process by which glucose is broken down into pyruvate, generating ATP and NADH.

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Krebs Cycle (Citric Acid Cycle)

A metabolic cycle that occurs in the mitochondria, oxidizing acetyl-CoA to produce ATP, NADH, and FADH2.

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Malate-Aspartate Shuttle

A shuttle system that transfers cytoplasmic NADH to the mitochondria, allowing for the production of ATP.

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Glycerol 3-Phosphate Shuttle

A shuttle system that transfers cytoplasmic NADH to the mitochondria, resulting in the production of FADH2.

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Glycogen

A storage form of glucose in the liver and muscle.

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Gluconeogenesis

The process of synthesizing glucose from non-carbohydrate sources, such as pyruvate.

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Glycogen Structure

The linear portion of the glycogen molecule is linked by α-(1,4) glycosidic bonds, while the branches are formed by α-(1,6) glycosidic bonds.

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Glycogen in Muscle

Glycogen stored in skeletal muscle is used primarily to meet the muscle's own energy demands, especially during periods of high ATP requirement.

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Glycogen in Liver

Glycogen stored in the liver serves as a glucose reserve for the entire body, playing a crucial role in maintaining blood glucose levels.

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Glycogen Synthesis

The process of synthesizing glycogen from glucose molecules, involving the activation of glucose 1-phosphate to UDP-glucose.

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Glycogen Degradation

The breakdown of glycogen into glucose molecules, involving the cleavage of glucose 1-phosphate units from the glycogen chains.

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Pentose Phosphate Pathway

The pathway that converts glucose 6-phosphate to pentose phosphates, producing NADPH and ribose 5-phosphate, essential for nucleotide synthesis.

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Bioenergetics

The study of energy transfer and utilization in biological systems.

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Gibbs Free Energy Change (ΔG)

The energy difference between reactants and products in a chemical reaction. A negative value indicates a spontaneous or exergonic reaction, while a positive value indicates a non-spontaneous or endergonic reaction.

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Exergonic reaction

A reaction that releases free energy and occurs spontaneously without energy input.

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Endergonic reaction

A reaction that requires energy input to occur, and does not happen spontaneously.

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Substrate-level phosphorylation

The process of generating ATP through direct transfer of a phosphate group from a substrate molecule to ADP.

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Pentose Phosphate Pathway (PPP)

A metabolic pathway that generates NADPH and pentose sugars (like ribose) for nucleotide synthesis.

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Glycogenolysis

The breakdown of glycogen, stored glucose, to release glucose molecules.

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Glycogenesis

The process of synthesizing glycogen from glucose molecules, for storage.

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Citric Acid Cycle (TCA Cycle)

A series of chemical reactions that occurs in the mitochondria, oxidizing acetyl-CoA to generate NADH, FADH2, and ATP.

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Electron carrier

A molecule that carries electrons in biological systems, such as NADH and FADH2.

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Study Notes

Bioenergetics

  • Bioenergetics is the transfer and utilization of energy in biological systems
  • Bioenergetics predicts if a process is possible, while kinetics measures the reaction rate
  • Enzymes cannot initiate a chemical reaction on their own
  • Molecules and reactions can be either exergonic or endergonic

Free Energy Change (ΔG)

  • ΔG = final energy - initial energy
  • A negative ΔG indicates a spontaneous reaction (exergonic) that releases energy
  • A positive ΔG indicates a nonspontaneous reaction (endergonic) that requires energy input

ATP Production

  • ATP is the primary energy currency for cells
  • Substrate-level phosphorylation
  • Oxidative phosphorylation

Carbohydrate Metabolism

  • Glucose is a critical energy source
  • Glycolysis, glycogenolysis, and gluconeogenesis are key pathways for glucose metabolism
  • Glycogen is used for glucose storage

Hormonal Regulation of Glycolysis

  • Hormones, like insulin and glucagon, regulate glucose uptake and utilization
  • Insulin typically increases glycolysis, while glucagon likely decreases it

Glycolysis - NAD+ Regeneration

  • Glycolysis requires NAD+ to occur
  • Fermentation produces NAD+ when oxygen is absent

TCA Cycle

  • The TCA cycle is crucial to capture high-energy electrons
  • The cycle's purpose is to harvest high-energy electrons from carbon fuels
  • Electrons are captured as NADH and FADH2 for ATP production

Oxidative Phosphorylation and ETC

  • The electron transport chain (ETC) is involved with oxidative phosphorylation
  • NADH and FADH2 carry high-energy electrons, resulting in ATP production

Electron Transport Chain

  • Electrons carried by NADH and FADH2 are captured by the system
  • Oxygen is reduced to water
  • ETC complexes pump H+ to outer membranes
  • Positive charge out of the membrane produces a flow into the matrix
  • ATP is synthesised

ETC - Overall Picture

  • NADH enters from Complex I, FADH2 from Complex II
  • One NADH pumps three protons
  • One FADH2 pumps two protons

Energy Gained from 1 mol Glucose

  • Glycolysis produces 2 ATP and 2 NADH
  • Pyruvate yields 2 NADH in the cytoplasm
  • Acetyl-CoA yields 6 NADH and 2 FADH2
  • The total number of ATPs produced from a mol of glucose depends on the shuttle systems used to transport NADH from the cytoplasm to the mitochondria

Transfer of Cytoplasmic NADH to Mitochondria

  • Malate Aspartate Shuttle and Glycerol 3-phosphate shuttle are used to transport NADH into the mitochondrial
  • NADH can't enter the mitochondria directly

Pentose Phosphate Pathway

  • It produces NADPH and ribose 5-phosphate
  • The pathway has oxidative and non-oxidative reactions
  • Ribose 5-phosphate is used in nucleotide synthesis.

Glycogen

  • A storage form of glucose in animals
  • Glycogen is predominantly stored in the liver and muscle
  • Glycogen degradation serves as a critical energy source
  • The synthesis involves glucose 1-P activation with UDP
  • Glycogen degradation occurs by cleaving glucose molecules

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Bioenergetics and Carbohydrate Metabolism PDF

Description

This quiz covers key concepts in bioenergetics, including energy transfer in biological systems and the role of free energy change (ΔG) in chemical reactions. It also addresses ATP production, carbohydrate metabolism, and the hormonal regulation of glycolysis. Test your understanding of these essential biochemical processes.

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