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  • IB Biology
    • Syllabus
    • General Resources
    • Practical scheme of work >
      • Practical activities (Labs)
      • Individual investigation
      • IB Write
      • Group 4 project
  • Core
    • 1. Cell biology >
      • 1.1 Introduction to cells
      • 1.2 Ultrastructure of cells
      • 1.3 Membrane structure
      • 1.4 Membrane transport
      • 1.5 The origin of cells
      • 1.6 Cell division
    • 2. Molecular biology >
      • 2.1 Molecules to metabolism
      • 2.2 Water
      • 2.3 Carbohydrates and lipids
      • 2.4 Proteins
      • 2.5 Enzymes
      • 2.6 Structure of DNA and RNA
      • 2.7 DNA replication, transcription and translation
      • 2.8 Cell respiration
      • 2.9 Photosynthesis
    • 3. Genetics >
      • 3.1 Genes
      • 3.2 Chromosomes
      • 3.3 Meiosis
      • 3.4 Inheritance
      • 3.5 Genetic modification and biotechnology
    • 4. Ecology >
      • 4.1 Species, communities and ecosystems
      • 4.2 Energy flow
      • 4.3 Carbon cycling
      • 4.4 Climate change
    • 5. Evolution and biodiversity >
      • 5.1 Evidence for evolution
      • 5.2 Natural selection
      • 5.3 Classification of biodiversity
      • 5.4 Cladistics
    • 6. Human physiology >
      • 6.1 Digestion and absorption
      • 6.2 The blood system
      • 6.3 Defence against infectious disease
      • 6.4 Gas exchange
      • 6.5 Neurons and synapses
      • 6.6 Hormones, homeostasis and reproduction
  • Additional higher level (AHL)
    • 7. Nucleic acids >
      • 7.1 DNA structure and replication
      • 7.2 Transcription and gene expression
      • 7.3 Translation
    • 8. Metabolism, cell respiration and photosynthesis >
      • 8.1 Metabolism
      • 8.2 Cell respiration
      • 8.3 Photosynthesis
    • 9. Plant biology >
      • 9.1 Transport in the xylem of plants
      • 9.2 Transport in the phloem of plants
      • 9.3 Growth in plants
      • 9.4 Reproduction in plants
    • 10. Genetics and evolution >
      • 10.1 Meiosis
      • 10.2 Inheritance
      • 10.3 Gene pools and speciation
    • 11. Animal physiology >
      • 11.1 Antibody production and vaccination
      • 11.2 Movement
      • 11.3 The kidney and osmoregulation
      • 11.4 Sexual reproduction
  • Options
    • A. Neurobiology and behaviour >
      • A.1 Neural development
      • A.2 The human brain
      • A.3 Perception of stimuli
      • A.4 Innate and learned behaviour (AHL)
      • A.5 Neuropharmacology (AHL)
      • A.6 Ethology (AHL)
    • B. Biotechnology and bioinformatics
    • C. Ecology and conservation >
      • C.1 Species and communities
      • C.2 Communities and ecosystems
      • C.3 Impacts of humans on ecosystems
      • C.4 Conservation of biodiversity
      • C.5 Population ecology (AHL)
      • C.6 Nitrogen and phosphorus cycles (AHL)
    • D. Human physiology
  • BISV Revision
  • Giving back - BioKQQAnswers

Essential idea: Energy is converted to a usable form in cell respiration.

Adenosine triphosphate (ATP) is the energy currency of cells. It is unstable and will breakdown into Adenosine diphosphate (ADP) and a phosphate releasing energy (as heat). The energy released by ATP is held in the bond between the second and the third phosphates. ATP can therefore be used as a coenzyme in many parts of the cells metabolism providing the energy needed for many reactions. Because of it's unstable nature it is only produced when needed carbohydrates, lipids (and sometimes proteins) provide more stable longer term storage for energy. The purpose of cell respiration therefore it to breakdown carbohydrates and lipids so that ATP can be produced from ADP when needed. The image to the above to the right shows the conversion of ADP and a phosphate into ATP.

ATP can be made by substrate level phosphorylation, but most commonly oxidative phosphorylation is used. The key component in oxidative phosphorylation is ATP synthase (above left). This enzyme sits embedded within the inner membrane of mitochondria. When hydrogen ions flow through ATP synthase the motive force is used to convert ADP and phosphate into ATP.

Understandings, applications and skills

8.2.U1 Cell respiration involves the oxidation and reduction of electron carriers.
8.2.U2 Phosphorylation of molecules makes them less stable.
8.2.U3 In glycolysis, glucose is converted to pyruvate in the cytoplasm.
8.2.U4 Glycolysis gives a small net gain of ATP without the use of oxygen. [The names of the intermediate compounds in gylcolysis is not required.]
8.2.U5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.
8.2.U6 In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide. [The names of the intermediate compounds in the Krebs cycle is not required.]
8.2.U7 Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD.
8.2.U8 Transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping.
8.2.U9 In chemiosmosis protons diffuse through ATP synthase to generate ATP.
8.2.U10 Oxygen is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water.
8.2.U11 The structure of the mitochondrion is adapted to the function it performs.
8.2.A1 Electron tomography used to produce images of active mitochondria.
8.2.S1 Analysis of diagrams of the pathways of aerobic respiration to deduce where decarboxylation and oxidation reactions occur.
8.2.S2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.
[Text in square brackets indicates guidance notes]

Starter

A playlist of musical summaries of the three key metabolic process involved in cell respiration by Mr W. Could you write your own one for the link reaction?


Presentation and notes

The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.


Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Below are the notes for this topic. Alternatively the 8.2 Cell respiration (AHL) notes - bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.


Quick quiz

Quick quiz Use the  BioK Quick Quiz on 8.2 Cell Respiration AHL (as directed) to check your understanding of the topic.

Weblinks

Cell Respiration
Cellular respiration by PH School
Cellular respiration by Sunamas Inc.
Cellular respiration a 3D animation by McGraw and Hill
Cellular respiration by Handwritten tutorials (below)

Glycolysis
Glycolysis by Smith University
How glycolysis works by McGraw and Hill
Glycolysis and fermentation in yeast by Indiana Uni has more detail than needed, but nicely illustrates that glycolysis is a metabolic pathway
Glycolysis by IUBMB again contains more detail than needed, but does neatly show the bond breaking and forming
Glycolysis by John Kyrk contains more detail than needed, but is a nice animation
Glycolysis by Cornell University
Glycolysis by National Louis University
Krebs cycle
Citric acid cycle by National Louis University
The citric acid cycle by Wiley
The citric acid cycle by Interactive concepts in biochemistry
How the Krebs cycle works by McGraw and Hill
Krebs cycle by John Kyrk contains more detail than needed, but is a nice animation

Oxidative Phosphorylation

Electron transport and chemiosmosis by
National Louis University
Oxidative Phosphorylation by
Interactive concepts in biochemistry
Oxidative phosphorylation
by Purdue University
Electron transport system and ATP synthesis by McGraw and Hill
Mitochondria/electron transport by John Kyrk contains more detail than needed, but is a nice animation

Nature of science

Paradigm shift—the chemiosmotic theory led to a paradigm shift in the field of bioenergetics. (2.3)

To find out more about the development of chemiosmotic theory uses the links:
http://biologyjunction.com/chemiosmotic_theory.htm
http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1978/press.htm

Theory of knowledge

Peter Mitchell’s chemiosmotic theory encountered years of opposition before it was finally accepted. For what reasons does falsification not always result in an immediate acceptance of new theories or a paradigm shift?
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