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Attempt either A or B - Scottish Highers Biology - Question 3 - 2019
Question 3
Attempt either A or B. Write your answer in the space below. A Write an account of ATP synthesis in the electron transport chain during cellular respiration. OR ... show full transcript
Worked Solution & Example Answer:Attempt either A or B - Scottish Highers Biology - Question 3 - 2019
Step 1
Write an account of ATP synthesis in the electron transport chain during cellular respiration.
Answer
ATP synthesis in the electron transport chain occurs on the inner membrane or cristae of the mitochondrion. The process begins when NADH and FADH₂, carrying electrons and hydrogen ions, are delivered to the electron transport chain.
As electrons are passed along the series of protein carriers, they release energy. This energy is utilized to pump hydrogen ions from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient.
The hydrogen ions then flow back into the matrix through ATP synthase, a protein complex that harnesses this flow to synthesize ATP from ADP and inorganic phosphate (Pi). The final step of this process is the production of ATP, enabling the cell to perform various essential functions.
Step 2
Write an account of competitive and feedback inhibition of enzymes.
Answer
Competitive inhibition occurs when an inhibitor binds to the active site of an enzyme, preventing substrate binding. This type of inhibition can often be reversed by increasing the concentration of the substrate.
In contrast, feedback inhibition takes place when an end product of a metabolic pathway inhibits an upstream enzyme. This regulation occurs at a critical/high concentration of the end product, which binds to an allosteric site on the enzyme, thus blocking its activity. This mechanism ensures that the pathway is efficiently regulated according to the cellular needs.