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How could a mutation in DNA affect polypeptide production? How could a change in a polypeptide affect cell activity? - HSC - SSCE Biology - Question 25 - 2008 - Paper 1
Question 25
How could a mutation in DNA affect polypeptide production? How could a change in a polypeptide affect cell activity?
Worked Solution & Example Answer:How could a mutation in DNA affect polypeptide production? How could a change in a polypeptide affect cell activity? - HSC - SSCE Biology - Question 25 - 2008 - Paper 1
Step 1
How could a mutation in DNA affect polypeptide production?
Answer
A mutation in the DNA sequence can lead to changes in the mRNA transcribed from that DNA. This is because the DNA sequence encodes the genetic information that determines which amino acids are incorporated into a polypeptide chain during protein synthesis.
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Types of Mutations: A point mutation may cause a single amino acid to change (missense mutation), lead to a premature stop codon (nonsense mutation), or have no effect at all (silent mutation). Each type can significantly impact the resultant polypeptide.
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Transcription and Translation Alterations: If a mutation alters the coding region of a gene, it may disrupt the normal transcription of mRNA or the subsequent translation into a polypeptide, leading to nonfunctional proteins.
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Functional Consequences: The resulting polypeptide could have an altered structure, leading to a loss of function, reduced activity, or gain of new functions, ultimately affecting the organism's phenotype.
Step 2
How could a change in a polypeptide affect cell activity?
Answer
A change in a polypeptide can lead to alterations in its three-dimensional structure, which is crucial for its functionality.
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Enzyme Activity: If the polypeptide is an enzyme, any change might affect the active site, thereby influencing substrate binding, catalytic efficiency, and overall metabolic pathways.
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Signal Transduction: Polypeptides that function as receptors or signaling molecules can alter cell communication. A change may cause overactivity or inactivity in signaling pathways, leading to inappropriate cellular responses.