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In this chapter of IBDP Biology, we will learn about the structure and function of Mitochondria.
Shape and size
- rod-shaped or thread-like.
- between 0.5-1.0 µm in diameter and 2-5 µm long, although some can be 10 µm long.
- moved around within cells by the cytoskeleton (microtubules).
Matrix
- When it comes to IBDP Biology, this is where the link reaction and Krebs cycle takes place. It contains enzymes that catalyse the stages of these reactions - coenzyme NAD oxaloacetate - 4-carbon compound that accepts acetate from the link reaction.
- mitochondrialDNA, some of which codes for mitochondrial enzymes and other proteins.
- mitochondrial ribosomes where these proteins are assembled.
Outer Membrane
- Made of the phospholipid composition which contains proteins, some of which form channels or carriers that allow the passage of molecules such as pyruvate, or other proteins such as enzymes.
Inner Membrane
- When it comes to IBDP Biology, the electron carriers are protein complexes, arranged in electron transport chains
- Each electron carrier is an enzyme, each associated with a cofactor
- The cofactors can accept and donate electrons because the iron atoms can become reduced (to Fe2+) by accepting an electron and oxidised (to Fe3+) by donating an electron to the next electron carrier.
- Some of the electron carriers also have a coenzyme that pumps protons from the matrix to the intermembrane space.
- Protons flow down a proton gradient, through the ATP synthase enzymes, from the intermembrane space into the matrix - this is called chemiosmosis. The force of this flow drives the rotation of part of the enzyme and allows ADP and Pi to be joined to make ATP
- The ATP synthase enzymes:
1. are large and protrude from the inner membrane into the matrix.
2. are also known as stalked particles.
3. allow protons to pass through them.
This is the end of the topic
