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The diagram below shows the structure of tryptophan - VCE - SSCE Biology - Question 1 - 2023 - Paper 1
Question 1
The diagram below shows the structure of tryptophan. **a. To what group of biological monomers does tryptophan belong? Use information in the diagram to justify you... show full transcript
Worked Solution & Example Answer:The diagram below shows the structure of tryptophan - VCE - SSCE Biology - Question 1 - 2023 - Paper 1
Step 1
a. To what group of biological monomers does tryptophan belong?
Answer
Tryptophan is classified as an amino acid. As illustrated in the diagram, it possesses an amine group ( ext{-NH}_2), a carboxyl group ( ext{-COOH}), and a variable R group. These characteristics are defining features of amino acids, making tryptophan part of this group of biological monomers.
Step 2
b. Please compare the two mechanisms of regulation.
Answer
In regulation of tryptophan synthesis, there are two mechanisms: repression and attenuation.
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Repression: When tryptophan (trp) levels are high, two tryptophan amino acids bind to the repressor, causing it to undergo a conformational change. This change enables the repressor to bind to the operator region, thereby inhibiting RNA polymerase from transcribing the structural genes.
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Attenuation: In this mechanism, when trp levels are high, RNA polymerase begins transcribing the leader or attenuator sequence. This sequence contains two trp codons. As the ribosome moves over these codons, it forms a hairpin loop structure, which results in the detachment of both RNA polymerase and the ribosome.
Both repression and attenuation operate to regulate trp levels in prokaryotic cells, ensuring that synthesis only occurs when necessary.