Practise ATP, respiratory substrates and aerobic or anaerobic pathways while calculating RQ, analysing respirometers and tracking carbon and reduced coenzymes.
There are many mitochondria located in the presynaptic knobs of neuromuscular junctions and in the sarcomeres of muscle fibres of striated muscle.
Explain the need for many mitochondria in the presynaptic knobs and in the sarcomeres.
Oxygen is needed for aerobic respiration in cells.
In eukaryotic cells, the mitochondrion is the organelle used for aerobic respiration.
Fig. 1.1 shows a transmission electron micrograph of a mitochondrion.
Fig. 1.1
Table 1.1 lists the four stages of aerobic respiration.
With reference to Fig. 1.1, complete Table 1.1 using the letters A-D to show where each stage occurs.
Each letter may be used once, more than once or not at all.
Table 1.1
In anaerobic conditions, no ATP can be synthesised by oxidative phosphorylation because the process stops.
Explain why ATP synthesis by oxidative phosphorylation stops in anaerobic conditions.
Up to 60\% of the ATP that is produced in cancer cells comes from lactate fermentation of glucose, even though oxygen is present.
Scientists are developing cancer treatments to inhibit the enzyme that catalyses the last step of lactate fermentation.
Explain how the inhibition of this enzyme reduces the production of ATP in cancer cells.
The Krebs cycle was named after the biochemist Sir Hans Krebs, who worked out the sequence in 1937.
Fig. 1.1 is an outline of the Krebs cycle.
Fig. 1.1
Identify substances P-U.
P
Q
R
S
T
U
Describe how ATP is produced from ADP in the Krebs cycle.
Describe and explain the features of ATP that make it suitable as the universal energy currency.
Glycolysis is a biochemical pathway that occurs in the cytoplasm of cells.
In glycolysis, a molecule of glucose is metabolised to two molecules of pyruvate. The process is outlined in Fig. 1.1.
Fig. 1.1
Explain why glucose is phosphorylated at the beginning of glycolysis.
Suggest one use of the reduced NAD that is produced in glycolysis.
Name the type of phosphorylation reaction by which ATP is made during glycolysis.
Pyruvate can enter the mitochondrion by active transport.
Describe the main conditions that are required for pyruvate to enter the mitochondrion by active transport.
Pyruvate is involved in the link reaction in the matrix of the mitochondrion.
Describe the link reaction.