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Describe three roles of membranes within cells.

Compartmentalisation - as different organelle's different metabolic reaction require different optimum environments such as pH and temperature. Site of chemical reactions such as photosynthesis or respiratio...
Answered by • Biology tutor
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How are action potentials transmitted across synapses?

When an action potential is transmitted from one neurone to another it has to be sent across a small gap - called the synapse . Firstly, the action potential arrives at the presynaptic neurone (‘pre’ means b...
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Answered by Sophie M. • Biology tutor
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Describe how a neurotransmitter, such as acetylcholine, is released from a brain cell.

When an action potential reaches the presynaptic bouton, it causes an influx of calcium into the nerve cell ending. This, in turn, causes vesicles containing the neurotransmitter (acetylcholine) to move to a...
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Answered by Zoe G. • Biology tutor
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What are the main features of the genetic code and can you explain them to me?

A sequence of three DNA nucleotide bases makes up a triplet. This triplet codes for one of 20 specific amino acids. The genetic code is universal because it is the same in all living organisms. For example, ...
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Answered by Amy D. • Biology tutor
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In a DNA molecule 28% of all bases found were Adenine. What are the remaining bases and their percentages in this molecule?

first remember your base pairs: Adenine binds to Thymine and then Cytosine binds to Guanine. So if 28% are Adenine then 28% must also be Thymine. 28+28= 56% so 100-56 gives you the remaining percentage which...
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Answered by John O. • Biology tutor
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