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When a nerve impulse arrives at a synapse, it causes the release of neurotransmitter from vesicles in the presynaptic knob - AQA - A-Level Biology - Question 1 - 2017 - Paper 3
Question 1
When a nerve impulse arrives at a synapse, it causes the release of neurotransmitter from vesicles in the presynaptic knob. The arrival of the nerve impulse leads t... show full transcript
Worked Solution & Example Answer:When a nerve impulse arrives at a synapse, it causes the release of neurotransmitter from vesicles in the presynaptic knob - AQA - A-Level Biology - Question 1 - 2017 - Paper 3
Step 1
0 1 . 2 - Use your knowledge of how myosin and actin interact to suggest how the myosin molecule moves the mitochondrion towards the presynaptic membrane.
Answer
Myosin heads attach to actin filaments and perform a power stroke by bending. This action pulls the mitochondrion along the actin filaments towards the presynaptic membrane. The myosin heads undergo conformational changes, which effectively moves the mitochondrion by utilizing the energy derived from ATP.
Step 2
0 1 . 3 - Suggest and explain one advantage of the movement of mitochondria towards the synapse.
Answer
One advantage of the movement of mitochondria towards the synapse is the provision of additional ATP for energy. These mitochondria can produce ATP needed for the active transport of ions and the synaptic processes, such as the re-synthesis and re-absorption of neurotransmitters. This is crucial for maintaining efficient neurotransmission, especially when nerve impulses arrive frequently at the synapse.