WEILAI Online Academic assistant
WEILAI Online Academic assistant
Back to 课程

Biology_A-level_Cie

0% Complete
0/0 Steps
  1. 1-1-the-microscope-in-cell-studies
    5 主题
  2. 1-2-cells-as-the-basic-units-of-living-organisms
    5 主题
  3. 2-1-testing-for-biological-molecules
    3 主题
  4. 2-2-carbohydrates-and-lipids
    8 主题
  5. 2-3-proteins
    6 主题
  6. 2-4-water
    2 主题
  7. 3-1-mode-of-action-of-enzymes
    5 主题
  8. 3-2-factors-that-affect-enzyme-action
    8 主题
  9. 4-1-fluid-mosaic-membranes
    4 主题
  10. 4-2-movement-into-and-out-of-cells
    12 主题
  11. 5-1-replication-and-division-of-nuclei-and-cells
    6 主题
  12. 5-2-chromosome-behaviour-in-mitosis
    2 主题
  13. 6-1-structure-of-nucleic-acids-and-replication-of-dna
    4 主题
  14. 6-2-protein-synthesis
    5 主题
  15. 7-1-structure-of-transport-tissues
    4 主题
  16. 7-2-transport-mechanisms
    7 主题
  17. 8-1-the-circulatory-system
    7 主题
  18. 8-2-transport-of-oxygen-and-carbon-dioxide
    5 主题
  19. 8-3-the-heart
    4 主题
  20. 9-1-the-gas-exchange-system
    6 主题
  21. 10-1-infectious-diseases
    3 主题
  22. 10-2-antibiotics
    3 主题
  23. 11-1-the-immune-system
    4 主题
  24. 11-2-antibodies-and-vaccination
    6 主题
  25. 12-1-energy
    5 主题
  26. 12-2-respiration
    11 主题
  27. 13-1-photosynthesis-as-an-energy-transfer-process
    8 主题
  28. 13-2-investigation-of-limiting-factors
    2 主题
  29. 14-1-homeostasis-in-mammals
    8 主题
  30. 14-2-homeostasis-in-plants
    3 主题
  31. 15-1-control-and-coordination-in-mammals
    12 主题
  32. 15-2-control-and-coordination-in-plants
    3 主题
  33. 16-1-passage-of-information-from-parents-to-offspring
    5 主题
  34. 16-2-the-roles-of-genes-in-determining-the-phenotype
    7 主题
  35. 16-3-gene-control
    3 主题
  36. 17-1-variation
    4 主题
  37. 17-2-natural-and-artificial-selection
    7 主题
  38. 17-3-evolution
    2 主题
  39. 18-1-classification
    5 主题
  40. 18-2-biodiversity
    7 主题
  41. 18-3-conservation
    6 主题
  42. 19-1-principles-of-genetic-technology
    11 主题
  43. 19-2-genetic-technology-applied-to-medicine
    4 主题
  44. 19-3-genetically-modified-organisms-in-agriculture
    2 主题
  45. 1-1-the-microscope-in-cell-studies
  46. 1-2-cells-as-the-basic-units-of-living-organisms
  47. 2-1-testing-for-biological-molecules
  48. 2-2-carbohydrates-and-lipids
  49. 2-3-proteins
  50. 2-4-water
  51. 3-1-mode-of-action-of-enzymes
  52. 3-2-factors-that-affect-enzyme-action
  53. 4-1-fluid-mosaic-membranes
  54. 4-2-movement-into-and-out-of-cells
  55. 5-1-replication-and-division-of-nuclei-and-cells
  56. 5-2-chromosome-behaviour-in-mitosis
  57. 6-1-structure-of-nucleic-acids-and-replication-of-dna
  58. 6-2-protein-synthesis
  59. 7-1-structure-of-transport-tissues
  60. 7-2-transport-mechanisms
  61. 8-1-the-circulatory-system
  62. 8-2-transport-of-oxygen-and-carbon-dioxide
  63. 8-3-the-heart
  64. 9-1-the-gas-exchange-system
  65. 10-1-infectious-diseases
  66. 10-2-antibiotics
  67. 11-1-the-immune-system
  68. 11-2-antibodies-and-vaccination
  1. Biology_A-level_Cie
  2. 12-2-respiration
  3. structure-and-function-of-mitochondria
课 26, 主题 8
In Progress

structure-and-function-of-mitochondria

课 Progress
0% Complete

Structure & function of the mitochondria

  • Mitochondria are rod-shaped organelles 0.5 – 1.0 µm in diameter

  • They are the site of aerobic respiration in eukaryotic cells

  • The function of mitochondria is to synthesise ATP

  • Synthesis of ATP in the mitochondria occurs during the last stage of respiration called oxidative phosphorylation

    • This relies on membrane proteins that make up the ‘electron transport chain’ and the ATP synthase enzyme—the details of this are covered later in the notes

Diagram of a mitochondrion with labelled parts: matrix, ribosome, mitochondrial DNA, granule, outer and inner membranes, intermembrane space, cristae.
The structure of a mitochondrion

Structure

  • Mitochondria have two phospholipid membranes, an outer and an inner membrane

  • The outer membrane is:

    • Smooth

    • Permeable to several small molecules

  • The inner membrane is:

    • Folded (cristae)

    • Less permeable

    • The site of the electron transport chain (used in oxidative phosphorylation)

    • Location of ATP synthase (used in oxidative phosphorylation)

  • The intermembrane space:

    • Has a low pH due to the high concentration of protons

    • The concentration gradient across the inner membrane is formed during oxidative phosphorylation and is essential for ATP synthesis

  • The matrix:

    • Is an aqueous solution within the inner membranes of the mitochondrion

    • Contains ribosomes, enzymes and circular mitochondrial DNA necessary for mitochondria to function

Diagram of a mitochondrion showing a blue oval shape with pink inner folds. Surrounding area has scattered red and grey speckles.
Electron micrograph of mitochondria

Relationship between structure and function

  • The structure of mitochondria makes them well-adapted to their function

  • They have a large surface area due to the presence of cristae (inner folds) which enables the membrane to hold many electron transport chain proteins and ATP synthase enzymes

  • More active cell types can have larger mitochondria with longer and more tightly-packed cristae to enable the synthesis of more ATP because they have a larger surface area

  • The number of mitochondria in each cell can vary depending on cell activity

    • Muscle cells are more active and have more mitochondria per cell than fat cells due to the differing levels of metabolic activity in those cell types

    • And the resulting different levels of demand for ATP in those cells

Examiner Tips and Tricks

Exam questions can sometimes ask you to explain how the structure of a mitochondrion helps it carry out its function effectively. It is not enough to say that cristae increase the surface area of the inner membrane. You need to explain that an increased surface area of the inner membrane means there are more electron transport chain carriers and ATP synthase enzymes which results in more ATP being produced.

Be prepared to identify the different structures and locations in a mitochondrion from an electron micrograph.