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Explain how a single base substitution causes a change in the structure of this polypeptide - AQA - A-Level Biology - Question 2 - 2019 - Paper 1
Question 2
Explain how a single base substitution causes a change in the structure of this polypeptide. Do not include details of transcription and translation in your answer.... show full transcript
Worked Solution & Example Answer:Explain how a single base substitution causes a change in the structure of this polypeptide - AQA - A-Level Biology - Question 2 - 2019 - Paper 1
Step 1
Change in (sequence of) amino acid(s)/primary structure
Answer
A single base substitution in the DNA sequence can lead to a change in the corresponding mRNA sequence. This alteration can cause a different amino acid to be incorporated into the polypeptide chain during protein synthesis. Since the primary structure of a protein is determined by the sequence of amino acids, any change in the DNA base sequence can result in a different primary structure.
Step 2
Change in hydrogen/ionic/disulfide bonds
Answer
The introduction of a different amino acid may affect how the protein folds due to changes in the chemical properties of the amino acids involved. For instance, a hydrophobic amino acid could replace a hydrophilic one, leading to altered interactions and potentially destabilizing certain structures such as hydrogen bonds, ionic bonds, or disulfide bonds.
Step 3
Alters tertiary/3° structure
Answer
As the protein’s primary structure is altered, this may lead to significant changes in the tertiary structure (3D shape) of the protein. The unique folding pattern depends on the specific interactions between various side chains, and any modification can influence the final conformation of the protein, potentially impacting its functional properties.