BiologyCode 9700
Respiration
What this topic asks you to be able to do
- State where in a eukaryotic cell each of the four stages of aerobic respiration happens: oxidative phosphorylation takes place on the inner mitochondrial membrane, the link reaction and the Krebs cycle both take place in the mitochondrial matrix, and glycolysis takes place in the cytoplasm
- outline glycolysis: glucose is phosphorylated, then fructose 1,6-bisphosphate (6C) is split into two triose phosphate molecules (3C), each of which is oxidised further to form pyruvate (3C), producing ATP and reduced NAD along the way
- explain that, if oxygen is present, pyruvate is transported into mitochondria where it participates in the link reaction
- describe the link reaction, including what coenzyme A does in moving acetyl (2C) groups
- outline the Krebs cycle, explaining that oxaloacetate (4C) accepts the 2C fragment carried by acetyl coenzyme A, giving citrate (6C), and that a series of small steps then turns citrate back into oxaloacetate
- explain that reactions of the Krebs cycle involve decarboxylation and dehydrogenation, and that NAD and FAD coenzymes are reduced
- describe what NAD and FAD do when they pass hydrogen on to carriers located in the inner mitochondrial membrane
- explain that, in oxidative phosphorylation: hydrogen atoms are separated into energetic electrons and protons; as the energetic electrons move along the electron transport chain they give out energy; this energy is used to drive protons across the inner membrane of the mitochondrion; the protons diffuse back into the mitochondrial matrix through ATP synthase (facilitated diffusion), which supplies the energy to make ATP; and oxygen is the final electron acceptor, forming water
- describe how mitochondrial structure relates to what mitochondria do, using diagrams and electron micrographs
- outline anaerobic respiration both in yeast, where it is ethanol fermentation, and in mammals, where it is lactate fermentation
- explain why aerobic conditions give a far larger energy yield from respiration than anaerobic conditions do (a thorough breakdown of how much ATP glucose yields when respired aerobically is not expected)
- explain the ways in which rice is suited to growing with its roots immersed in water, limited to aerenchyma formation in the roots, ethanol fermentation in the roots and quicker stem growth
- describe and perform experiments with redox indicators, including DCPIP and methylene blue, to determine how temperature and substrate concentration influence the rate of respiration in yeast
- describe and carry out investigations in which simple respirometers are used to find out how the rate of respiration depends on temperature