mitochondria

Question 1

structure & function

Answer 1

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

Question 2

outer membrane

Answer 2

smooth
permeable to several small molecules

Question 3

inner membrane

Answer 3

Folded (cristae)
Less permeable
The site of the electron transport chain (used in oxidative phosphorylation)
Location of ATP synthase (used in oxidative phosphorylation)

Question 4

intermembrane space

Answer 4

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

Question 5

matrix

Answer 5

Is an aqueous solution within the inner membranes of the mitochondrion
Contains ribosomes, enzymes and circular mitochondrial DNA necessary for mitochondria to function

Question 6

relationship between structure & function

Answer 6

The structure of mitochondria makes them well adapted to their function:

1.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

2. 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
3. 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