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Explain how a nerve impulse causes the chambers of the heart to contract (6).

The heart's excitation is myogenic and therefore can be started without any transmission from the brain. The sino-atrial node is found behind the posterior wall of the left atrium and is where the action pot...
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Answered by Jeremy S. • Biology tutor
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What happens during mitosis?

There are several phases to mitosis: interphase, prophase, metaphase, anaphase, and telophase. In interphase, the cell duplicates it’s organelles and chromosomes, ready for mitosis. In prophase, the chromoso...
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Answered by Julia S. • Biology tutor
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What is the difference between competetive and non-competetive inhibitors?

Competetive inhibitors are the same shape as the enzyme substrate. They bind directly to the active site of the enzyme, preventing the binding of the substrate. Therefore, if you increase the concentration o...
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Answered by Andreas C. • Biology tutor
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Gene mutations can arise during DNA replication. Explain why different types of gene mutation may have different effects on the encoded polypeptide.

Gene mutations arise due to errors in DNA replication and include insertion, deletion, substitution, inversion, duplication and translocation of bases. Each triplet of bases encodes one amino acid. Therefore...
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Answered by Harriet O. • Biology tutor
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Describe the structure of proteins

Proteins are amino acid polymers, joined by peptide bonds which are formed via condensation reactions. The primary structure is the order of amino acids, secondary structure is the folding of polypeptide cha...
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Answered by Anthony C. • Biology tutor
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