Exercise Physiology Chapter 3 Flashcards

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Questions and Answers

Which of the following statements about glycolysis is correct?

  • Glycolysis involves the breakdown of glucose or glycogen into two molecules of pyruvate or lactate. (correct)
  • Glycolysis takes place in the mitochondria.
  • Glycolysis occurs only in aerobic conditions.
  • Glycolysis produces ATP exclusively from fat.

Where does aerobic production of ATP occur?

mitochondria

What are stored polysaccharides in muscle and other tissues in animals called?

glycogen

What is the rate limiting enzyme in glycolysis?

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

What is the calculated efficiency for aerobic respiration?

<p>34%</p> Signup and view all the answers

The first and second proton pumps in the electron transport chain transport ___ protons (H+) across mitochondrial inner membrane whereas the third proton pump moves ____ protons (H+).

<p>4;2</p> Signup and view all the answers

Triglycerides are comprised of?

<p>FFA and glycerol</p> Signup and view all the answers

What fats stored in muscle and adipose tissue play an important role as an energy substrate?

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

The activity of creatine kinase is increased by a rise in ____ levels in the muscle fiber.

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

What is the primary purpose of the Krebs cycle?

<p>complete the oxidation of foodstuffs using NAD and FAD as hydrogen (electron) carriers</p> Signup and view all the answers

Each pair of electrons passed through the electron transport chain from NADH to oxygen releases enough energy to produce a net production of?

<p>2.5 ATP</p> Signup and view all the answers

What is the simplest and most rapid method of producing ATP during exercise?

<p>ATP-CP system</p> Signup and view all the answers

Where are rate limiting enzymes often located?

<p>near the beginning of a metabolic pathway</p> Signup and view all the answers

Why do skeletal muscles store carbohydrate in the form of glycogen rather than glucose?

<p>storage of individual glucose molecules in the cell increases the osmotic pressure</p> Signup and view all the answers

What does the process of beta-oxidation involve?

<p>the breakdown of a fatty acid to acetyl-CoA</p> Signup and view all the answers

What are enzymes called kinases responsible for?

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

What is the caloric (kcal) yield of one gram of protein?

<p>4 kcal/g</p> Signup and view all the answers

What is the primary function of the Krebs cycle?

<p>complete the oxidation of carbohydrates, fats, and proteins</p> Signup and view all the answers

Why does FADH produce less ATP compared to NADH?

<p>the electrons from FADH are donated later in the electron transport chain than those by NADH</p> Signup and view all the answers

What is the rate-limiting enzyme in the electron transport chain?

<p>cytochrome oxidase</p> Signup and view all the answers

Which of the following statements is true concerning the electron transport chain?

<p>The primary purpose of the electron transport chain is to produce ATP and water. (A)</p> Signup and view all the answers

What enzyme catalyzes the formation of lactate from pyruvate?

<p>lactate dehydrogenase</p> Signup and view all the answers

Elevated blood levels of lactate dehydrogenase can assist in the diagnosis of which medical condition?

<p>myocardial infarction</p> Signup and view all the answers

Why is the actual net ATP yield from aerobic metabolism of one molecule of glucose different from the theoretical yield?

<p>it accounts for the requirement of energy for transport of ATP</p> Signup and view all the answers

In general, what happens to the contribution of anaerobic energy production as exercise intensity increases?

<p>greater contribution</p> Signup and view all the answers

What does the term lactate refer to?

<p>All of the above. (D)</p> Signup and view all the answers

In the hydrolytic model of oxidative phosphorylation, the four water tanks represent?

<p>the four energy pools in muscle</p> Signup and view all the answers

By definition, what is an endergonic reaction?

<p>a chemical reaction that requires energy to be added</p> Signup and view all the answers

What is required for the conversion of pyruvate to lactate?

<p>Both A and B. (C)</p> Signup and view all the answers

What is the rate limiting enzyme in the Krebs cycle?

<p>isocitrate dehydrogenase</p> Signup and view all the answers

How do enzymes increase the rate of reactions?

<p>lowering the energy of activation</p> Signup and view all the answers

What are coupled reactions?

<p>reactions that are linked together to drive a second reaction</p> Signup and view all the answers

What high level in the muscle fiber would slow glycolysis?

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

What happens to body temperature during exercise?

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

How many total ATP molecules can be produced from three molecules of NADH generated during one turn of the citric acid cycle?

<p>7.5 ATP</p> Signup and view all the answers

What are the two most important hydrogen (electron) carriers in bioenergetic chemical reactions?

<p>NAD and FAD</p> Signup and view all the answers

What is the net production of ATP resulting from muscle glycogen during glycolysis?

<p>3 molecules</p> Signup and view all the answers

What is the total ATP tally from the aerobic breakdown of glucose?

<p>32 ATP</p> Signup and view all the answers

What is the metabolic process of converting foodstuffs into a biologically usable form of energy called?

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

What is the immediate source of energy for muscular contraction?

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

Flashcards

Glycolysis

The process of breaking down glucose or glycogen into two pyruvate or lactate molecules.

Phosphofructokinase

The rate-limiting enzyme in glycolysis, responsible for controlling the overall pace of the process.

ATP Inhibition of Glycolysis

High levels of ATP signal the cell that it has enough energy, slowing down glycolysis by inhibiting phosphofructokinase.

Aerobic ATP Production

The process of generating ATP within the mitochondria using oxidative phosphorylation.

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Efficiency of Aerobic Respiration

The efficiency of aerobic respiration, indicating the amount of energy harvested from glucose.

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Actual ATP Yield from Glucose

The net ATP yield from aerobic metabolism of glucose, considering energy used for transport across the mitochondrial membrane.

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Krebs Cycle

The central metabolic pathway that oxidizes carbohydrates, fats, and proteins, producing NADH and FADH.

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Isocitrate Dehydrogenase

The rate-limiting enzyme in the Krebs Cycle, controlling the overall pace of the cycle.

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NADH Production in Krebs Cycle

NADH produced per cycle in the Krebs Cycle, contributing to ATP generation.

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Electron Transport Chain

The process of converting electron energy into ATP and water using a series of protein complexes.

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ATP Production from NADH

The energy generated by each pair of electrons from NADH in the electron transport chain.

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Cytochrome Oxidase

The rate-limiting enzyme in the electron transport chain, controlling the final step in the process.

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ATP Production from FADH

FADH generates less ATP than NADH because it donates electrons at a later stage in the chain.

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Triglycerides as Energy Substrates

Triglycerides are comprised of free fatty acids (FFA) and glycerol, serving as energy substrates.

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Glycogen

Stored polysaccharides in animals, serving as a readily available energy source.

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Creatine Kinase

The enzyme responsible for catalyzing the conversion of creatine and ADP to ATP.

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Lactate

A potential end-product of glycolysis, formed when pyruvate is reduced using NADH and H+.

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Lactate Dehydrogenase (LDH)

The enzyme responsible for converting pyruvate to lactate.

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Elevated LDH Levels

Elevated LDH levels can indicate myocardial infarction (heart attack).

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Exercise Intensity and Anaerobic Metabolism

Higher exercise intensity forces the body to rely more on anaerobic energy production, leading to lactate accumulation.

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Body Temperature and Enzyme Activity

Increased body temperature during exercise enhances enzyme activity, accelerating metabolic reactions.

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Bioenergetics

The study of energy transformations in biological systems.

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Enzymes

Biological catalysts that speed up chemical reactions by lowering activation energy.

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Coupled Reactions

Reactions where the energy released from one reaction is used to drive another reaction.

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ATP for Muscle Contraction

The immediate energy source for muscle contraction, with anaerobic pathways providing the fastest ATP synthesis.

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Total ATP from Aerobic Glucose Breakdown

The total ATP production from aerobic glucose breakdown, including the net yield and energy used for transport.

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Hydrolytic Model of Oxidative Phosphorylation

A model representing four energy pools in muscles: ATP, phosphocreatine, glycogen, and lactate.

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Study Notes

Glycolysis

  • Glycolysis breaks down glucose or glycogen into two molecules of pyruvate or lactate.
  • The rate-limiting enzyme in glycolysis is phosphofructokinase.
  • A high level of ATP slows glycolysis by inhibiting its rate-limiting enzyme.

Aerobic Production of ATP

  • ATP production occurs in the mitochondria via oxidative phosphorylation.
  • The calculated efficiency for aerobic respiration is approximately 34%.
  • The actual net ATP yield from aerobic metabolism of one glucose molecule accounts for energy usage in transport across the mitochondrial membrane.

Krebs Cycle

  • The primary function is to oxidize carbohydrates, fats, and proteins, forming NADH and FADH.
  • The rate-limiting enzyme in the Krebs cycle is isocitrate dehydrogenase.
  • Three molecules of NADH are produced per cycle, yielding approximately 7.5 ATP.

Electron Transport Chain

  • The chain converts electron energy to produce ATP and water.
  • Each pair of electrons from NADH releases enough energy for a net production of 2.5 ATP.
  • The rate-limiting enzyme in the electron transport chain is cytochrome oxidase.
  • FADH generates less ATP than NADH because it donates electrons later in the chain.

Energy Sources and Substrates

  • Triglycerides consist of free fatty acids (FFA) and glycerol, serving as energy substrates.
  • Stored polysaccharides in animals are referred to as glycogen.
  • Creatine kinase activity increases with rising ADP levels in muscle fibers.

Lactate and Its Role

  • Lactate is a potential end-product of glycolysis and the conjugate base of lactic acid.
  • The conversion of pyruvate to lactate requires lactate dehydrogenase (LDH) and NADH + H+.
  • Elevated lactate dehydrogenase levels can assist in diagnosing myocardial infarction.

Exercise Physiology

  • Higher exercise intensity leads to a greater reliance on anaerobic energy production.
  • Body temperature rise during exercise increases enzyme activity.

Bioenergetics and Reactions

  • Bioenergetics refers to converting foodstuffs into usable energy.
  • Enzymes, acting as catalysts, lower the activation energy of reactions.
  • Coupled reactions involve a sequence where the energy released from one drives another reaction.

Additional Key Points

  • The immediate energy source for muscle contraction is ATP, with anaerobic pathways being the fastest for ATP production.
  • The total ATP production from aerobic breakdown of glucose is 32 molecules.
  • The hydrolytic model of oxidative phosphorylation represents four energy pools in muscles.

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