5.2 Respiration

• What is the shape and size of mitochondria?

  Mitochondria are rod-shaped organelles 0.5 - 1.0 µm in diameter.
• What is the primary function of mitochondria?

  The function of mitochondria is to synthesize ATP.
• During which stage of respiration does ATP synthesis occur in mitochondria?

  ATP synthesis occurs during the last stage of respiration called oxidative phosphorylation.
• What are the components involved in oxidative phosphorylation?

  Oxidative phosphorylation relies on membrane proteins that make up the electron transport chain and the ATP synthase enzyme.
• What are the structural features of mitochondria?

  • Two phospholipid membranes
  • Outer membrane: smooth and permeable to small molecules
  • Inner membrane: folded (cristae) and less permeable
  • Intermembrane space: low pH due to high proton concentration
  • Matrix: aqueous solution containing ribosomes, enzymes, and circular mitochondrial DNA

  
• Why is the concentration gradient across the inner membrane important?

  The concentration gradient across the inner membrane is essential for ATP synthesis.
• What is the role of cristae in mitochondria?

  Cristae increase the surface area of the inner membrane, allowing for more electron transport chain proteins and ATP synthase enzymes.
• How do more active cell types differ in mitochondrial structure?

  More active cell types can have larger mitochondria with longer and more tightly packed cristae to enable the synthesis of more ATP.
• Which type of cells have more mitochondria per cell?

  Muscle cells have more mitochondria per cell than fat cells.
• What is the primary source of energy for nearly all organisms?

  The sun is the primary source of energy for nearly all organisms.
• How is light energy transformed in photosynthesis?

  Light energy from the sun is transformed into chemical potential energy in the synthesis of carbohydrates.
• What do carbohydrates formed during photosynthesis provide for organisms?

  Carbohydrates formed are used in the synthesis of ATP or modified to form usable organic molecules essential for metabolic processes.
• What is the equation for the breakdown of glucose during respiration?

  Glucose + oxygen → carbon dioxide + water + energy.
• What distinguishes autotrophs from heterotrophs?

  Autotrophs can synthesize their own usable carbon compounds from carbon dioxide, while heterotrophs require pre-made usable carbon compounds from food.
• What is the significance of the laws of thermodynamics in respiration and photosynthesis?

  According to the laws of thermodynamics, energy cannot be created or destroyed; it is transformed from one form into another.
• What is an example of an energy-requiring reaction in organisms?

  The sodium-potassium pump is an example of active transport requiring energy.
• What are the four stages of aerobic respiration and their locations?

  1. Glycolysis: occurs in the cell cytoplasm
  2. Link reaction: occurs in the matrix of the mitochondria
  3. Krebs cycle: occurs in the matrix of the mitochondria
  4. Oxidative phosphorylation: occurs at the inner membrane of the mitochondria

  
• What is produced during glycolysis?

  Glycolysis results in the production of 2 pyruvate molecules, a net gain of 2 ATP, and 2 reduced NAD.

  
• What happens to glucose during glycolysis?

  Glucose is phosphorylated, split into two triose phosphate molecules, and then converted into pyruvate.

  
• What is the net gain of ATP during glycolysis?

  The net gain of ATP during glycolysis is 2 ATP per glucose molecule.
• What is the role of NAD in glycolysis?

  NAD accepts hydrogen atoms during glycolysis to form reduced NAD.
• What is produced during the link reaction?

  The link reaction produces acetyl CoA, carbon dioxide, and reduced NAD.
• What is the function of coenzyme A in the link reaction?

  Coenzyme A binds to the acetyl group from pyruvate to form acetyl CoA, which enters the Krebs cycle.
• What is the Krebs cycle also known as?

  The Krebs cycle is also known as the citric acid cycle.
• What is the role of oxaloacetate in the Krebs cycle?

  Oxaloacetate accepts the 2C acetyl fragment from acetyl CoA to form citrate and is regenerated throughout the cycle.
• What are the products of the Krebs cycle?

  The Krebs cycle produces reduced NAD, reduced FAD, and ATP.
• What are the steps involved in the Krebs cycle?

  1. Acetyl CoA enters the cycle and combines with oxaloacetate to form citrate.
  2. Citrate undergoes decarboxylation and oxidation to regenerate oxaloacetate.
  3. Reduced NAD and FAD are produced.
  4. ATP is produced through substrate-linked phosphorylation.

  
• What is the role of NAD and FAD in aerobic respiration?

  NAD and FAD accept hydrogen atoms during respiration and transfer them to the electron transport chain.
• What happens to NAD and FAD when they accept hydrogen?

  When NAD and FAD accept hydrogen, they are reduced.
• What is the significance of the electron transport chain in respiration?

  The electron transport chain is where hydrogen atoms are removed from coenzymes, and it drives ATP synthesis through the movement of hydrogen ions.

  
• How does the movement of hydrogen ions contribute to ATP synthesis?

  The movement of hydrogen ions down the proton gradient back into the mitochondrial matrix drives ATP synthesis.
• What does OIL RIG stand for in the context of redox reactions?

  Oxidation Is Loss, Reduction Is Gain
• What role do hydrogen atoms play in the electron transport chain during respiration?

  They are transferred to the electron transport chain where they help in ATP synthesis.
• What happens to coenzymes when hydrogen atoms are removed during respiration?

  The coenzymes are oxidised.
• Why are electrons from reduced NAD (NADH) and reduced FAD (FADH2) important in the electron transport chain?

  They are given to the electron transport chain to facilitate ATP synthesis.
• What occurs when hydrogen ions from reduced NAD (NADH) and reduced FAD (FADH2) are lost?

  They are released into the electron transport chain.
• What is created as a result of the movement of hydrogen ions across the inner mitochondrial membrane?

  A proton gradient is established.
• How does the movement of hydrogen ions down the proton gradient contribute to ATP synthesis?

  It provides the energy required for ATP synthesis.
• What is oxidative phosphorylation?

  It is the last stage of aerobic respiration.
• Where does oxidative phosphorylation take place?

  At the inner mitochondrial membrane.