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Biology

A Level

Describe and explain how an action potential is generated (6 marks)

The membrane is at resting potential, -60mV inside compared to outside. It is polarised. 2. Na+ ion channels open and some Na+ ions diffuse into the neurone. 3. The membrane
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Answered by Rokshan E. • Biology tutor
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What is the difference between gene transcription and gene translation?

Both of these are key steps in gene expression to obtain proteins.

Transcription occurs first. It is the process, happening in the nucleus, where a specific segment of DNA is copied into RNA to for...

Answered by Madeleine G. • Biology tutor

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Enzymes known as endopeptidases aid digestion of proteins in the small intestine. why do they only bind to amino acids and not other foods ingested?

Model Answer: this is because enzymes are a protein with a specific tertiary structure which have an active site that is complementary to the substrate (in this case the amino acids of a protein) ultimate...

Answered by Charlotte B. • Biology tutor

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Which of these DNA mutations is likely to have the greatest effect on the structure of the encoded protein? Justify your answer. •Single base substitution •15 bases base deletion •Insertion of 2 bases

The most serious of these mutations will be the insertion of 2 bases. Becasue the genetic code is read in triplets, a 2 base insetion will alter the reading frame of the code causing a frameshift mutation...

Answered by Emma M. • Biology tutor

22150 Views

Describe the mechanism(s) as to which an enzyme binds to a substrate.

Two models have been proposed. The first being the 'Lock and Key Model' which simply describes the way in which the active site of an enzyme is complementary to the substrate shape, meaning that only the ...

Answered by Nicole B. • Biology tutor

3056 Views