5.7.2 Structure of the Mitochondrion Flashcards
What is the function of the mitochondrion?
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 synthesize 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
What is the structure of the mitochondrion?
Mitochondria have two phospholipid membranes
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 enzymes (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
What is the 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
