To determine which factor has a greater influence on protein levels, we need to consider the roles of polymerase affinity and positive transcription factor affinity in gene expression.
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Polymerase Affinity: RNA polymerase is essential for transcribing mRNA from DNA. Without sufficient polymerase affinity to the promoter region of a gene, mRNA synthesis would be inefficient or non-existent. Without mRNA, there can be no protein translation.
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Positive Transcription Factor Affinity: Positive transcription factors (PTFs) are vital for initiating transcription. They help to recruit RNA polymerase to the promoter, enhancing the likelihood of transcription occurring. If PTFs are absent or have low affinity, transcription may not initiate effectively, leading to lower levels of mRNA and thus lower protein synthesis.
Considering these roles, the following responses can be evaluated:
- Polymerase affinity has a greater influence because mRNA cannot be translated into proteins without it.
- Positive transcription factor affinity has a greater influence because you cannot turn genes on without it.
- Positive transcription factor affinity has a greater influence because you cannot start reading mRNA without it.
- Polymerase affinity has a greater influence because you cannot start reading mRNA without it.
The most accurate answer is:
Positive transcription factor affinity has a greater influence because you cannot turn genes on without it.
This is because while polymerase is crucial for the translation of mRNA into proteins, the initiation of transcription (turning the gene on) heavily relies on the binding of positive transcription factors to the promoter, which in turn facilitates polymerase's action. Thus, without the expression being initiated in the first place, no mRNA, and subsequently no protein levels, can be produced.