The diagram below represents three chemical reactions in the energy investment phase of glycolysis - Scottish Highers Human Biology - Question 4 - 2015
Question 4
The diagram below represents three chemical reactions in the energy investment phase of glycolysis.
(a) Identify the information, shown in the diagram, which confir... show full transcript
Worked Solution & Example Answer:The diagram below represents three chemical reactions in the energy investment phase of glycolysis - Scottish Highers Human Biology - Question 4 - 2015
Step 1
Identify the information, shown in the diagram, which confirms that this is the energy investment phase of glycolysis.
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Answer
ATP is broken down/used up/converted to ADP.
Step 2
Suggest how the binding of magnesium ions leads to an increase in enzyme activity.
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Answer
The binding of magnesium ions changes the shape/form of the active site to fit the substrate molecule better. This increases the enzyme's affinity for the substrate and lowers the activation energy.
Step 3
Choose an enzyme shown in the diagram which is catalysing a phosphorylation reaction.
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Answer
Enzyme 1 or Enzyme 3.
Explanation: Phosphorylation refers to the transfer of a phosphate group (from ATP) to a substrate.
Step 4
Describe the circumstances under which this reaction would go in the opposite direction to that shown in the diagram.
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Answer
This reaction is likely to occur when there is a buildup of fructose 6-phosphate or when ATP levels are low, shifting the balance towards glucose 6-phosphate.
Step 5
Explain how this feedback mechanism conserves the cell’s resources.
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Answer
This ensures the cell only uses ATP when required or that glucose is only metabolized when it is needed, thereby preventing unnecessary energy expenditure.
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