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(a) State that genes code for polypeptides, including enzymes
A gene is a length of DNA- sequence of nucleotide bases that code for one or more polypeptides

(b) Explain the meaning of the term genetic code
A sequence of nucleotide bases on a gene- provides a code with instructions for…

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Types of mutations:
1. point/ substitution ­ one base replaces another
2. insertion- one or more nucleotide bases are inserted into a length of DNA
3. deletion- one or more nucleotide pairs are deleted form a length of DNA


(f) Explain how mutations can have beneficial, neutral or harmful effects…

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2. Promoter region- where enzyme RNA polymerase binds to to binding the transcription of
the structural genes

When lactose is absent:
Regulator gene is expressed- repressor protein is synthesised and binds to operator region
This covers the promoter region
RNA polymerase cannot attack to the promoter region so the structural…

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It is controlled by cell signalling including cytokines. It is important in development. The rates of
apoptosis need to be balance
Too much- cell loss and degeneration
Too little- tumours

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