Cell respiration 8.2 HL

This topic looks at the details of glycolysis, the link reaction and the krebs cycle.  The structure of mitochondria is related to its function and the amazing process of chemiosmosis is outlined leading to the production of water and ATP

Key concepts

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Essentials

These slides summarise the essential understanding and skills in this topic. 
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Summary

Summary list for 8.2 Respiration

Introduction to reactions in respiration

  • Cell respiration involves:
  • the oxidation and reduction of electron carriers.
  • the phosphorylation of molecules which makes them less stable.
  • decarboxylation removes a carbon atom from a molecule.

Glycolysis & the Krebs cycle

  • Glycolysis is the conversion of glucose to pyruvate in the cytoplasm giving a small net gain of ATP (without the use of oxygen).
  • Aerobic cell respiration converts the pyruvate by decarboxylation and oxidation, into an acetyl compound.
  • In the link reaction acetyl is attached to coenzyme A to form acetyl coenzyme A.
  • In the Krebs cycle;
    • the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide.
    • reduced NAD and FAD (NADH+H+ and FADH+) carry energy released by oxidation reactions to the cristae of the mitochondria.

The electron transport chain & Mitochondrion structure.

  • the electron transport chain in the membrane of the cristae is coupled to proton pumping.
  • oxygen is the final electron acceptor.
  • In chemiosmosis protons diffuse through ATP synthase to generate ATP.
  • Oxygen binds with the free protons to maintain the hydrogen gradient and resulting in the formation of water.
  • The structure of the mitochondrion is adapted its function. Annotate a diagram of a mitochondrion to show these adaptations.

Skills

  • Active mitochondria have been studies using electron tomography - images.
  • students will be able to identify where decarboxylation and oxidation reactions occur in diagrams of the pathways of aerobic respiration.
  • Guidance: The names of the intermediate compounds in glycolysis and the Krebs cycle are not required.

Mindmaps

This diagram summaries the main sections of topic 8.2.
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Exam style questions

Exam style question about cell respiration.

Explaining the link reaction is an important skill from this topic.

Answer the question below, on a piece of paper, then check your answer against the model answer below.

Compare and contrast the link reaction and the krebs cycle . [2]

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Extra exam style question on mitochondria.   Click to open.

Exam style question about mitochondria and respiration.

The relationship between the structure and function of the mitochondrion is an important aspect of aerobic respiration.

Outline six ways in which the structure of a mitochondrion is related to its function. (6 marks)







Examiner's hint:  In an 'Outline' question give the most important points with an explanation or detail for each.

Where there are six ways asked for it's best to try to outline seven, in case one point is incorrect.
Avoid any points which contradicts another.
Try to put the structural feature with the function.

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Extra exam question on the role of oxygen in aerobic respiration    Click to open.

The role of oxygen in aerobic respiration is an important concept in this topic.

Answer the question below, on a piece of paper, then check your answer against the model answer below.

Describe the role of oxygen in the production of ATP aerobic respiration (4 marks).





Hint: Your response must link the use of oxygen to the production of ATP.
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Test yourself

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Drag and drop activities

Test your ability to construct biological explanations using the drag and drop questions below.

Test your knowledge of biological explanations using the drag and drop questions below.

Summary of the generation of ATP by aerobic respiration.

Note: This is a summary, it does not contain the details.

Drag and drop the correct term into the gap to describe a summary of ATP formation by oxidative phosphorylation.

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carbon dioxide NAD oxygen oxidation protons oxidative phosphorylation synthase Calvin inner electrons Krebs outer acceptor potential

Reduced and FAD produced in the cycle donate to the electron transport chain (ETC) in the mitochondrial membrane. These electrons are passed down the ETC in the membrane causing to accumulate in the intermembrane space.

The accumulated protons pass through an ATP pore in the membrane into the stroma (chemiosmosis), losing electrical energy which is used to drive the formation of ATP by . The electrons and protons then combine with to form water.

The ETC cannot function in the absence of oxygen as it is the final electron at the end of the ETC.

Explanation: The ETC creates the proton gradient for ATP formation. The role of oxygen is to act as tyhe final electron acceptor for the ETC.


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