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When a nerve impulse arrives at a synapse, it causes the release of neurotransmitter from vesicles in the presynaptic knob. Describe how.

Membrane depolarisation arrives at the pre-synpase and causes Ca2+ voltage-gated channels to open. This allows Ca2+ ions to diffuse in the presynapse via the activated Ca2+ channels. Ca2+ influx in the presy...
GM
Answered by Georgios M. • Biology tutor
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How to we acquire monoclonal antibodies

Firstly - What are antibodies? Antibodies are part of the immune system which are specific to the pathogen. They help destroy the pathogen.And what are monoclonal antibodies? They're just antibodies that are...
HG
Answered by Helen G. • Biology tutor
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How is DNA replicated?

DNA replication starts at an origin - eukaryotic chromosomes have multiple origins whereas prokaryotic chromosomes have only one. Here an enzyme called helicase separates the existing ("parental") ...
SA
Answered by Sarah A. • Biology tutor
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The pancreas is an endocrine and an exocrine gland, indicate both of these functions.

Pancreas' exocrine function is mainly aimed at digesting food. It secrets pancreatic digestive enzymes which travel into the pancreatic duct and are released into the duodenum. Pancreas' endocrine function i...
FK
Answered by Fady K. • Biology tutor
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I don't understand how muscle contraction starts, can you explain it?

So, if we looks at the sarcomere of the muscle (which is from one Z line to another) you'll see a thicker looking strand/filament called myosin and thinner strands called actin. Myosin has bulbous structures...
MK
Answered by Monica K. • Biology tutor
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