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Question

Difficulty: HardClause Boundaries and Linking

In molecular biology, histone acetylation plays a crucial role in regulating gene expression by modifying chromatin structure. When acetyl groups attach to histones, the DNA wraps more loosely around these ______ transcription factors can then access the genetic sequence and initiate the process of transcription. Consequently, this modification is vital for cell differentiation.

Which choice completes the text so that it conforms to the conventions of Standard English?

  1. proteins;Answer
  2. B
    proteins,
  3. C
    proteins
  4. D
    proteins, although

Answer

The choice ending with a semicolon ('proteins;') is the correct answer because it successfully links two independent clauses without a coordinating conjunction.
The correct answer is the option ending with a semicolon. The sentence contains two independent clauses: the first begins with the subordinate clause 'When acetyl groups attach to histones' followed by the main clause 'the DNA wraps more loosely around these proteins,' and the second clause is 'transcription factors can then access the genetic sequence...' A semicolon is a standard and correct way to link two closely related independent clauses.

Step-by-Step Solution

1
Identify the clause boundaries in the sentence containing the blank.
The sentence contains two distinct clauses: the first begins with 'When acetyl groups attach...' and ends at the blank, and the second begins with 'transcription factors can then...'
Understanding where one clause ends and the next begins is necessary to determine the correct punctuation or conjunction.
2
Analyze the grammatical structure of both clauses.
The first clause ('When acetyl groups attach to histones, the DNA wraps more loosely around these proteins') is an independent clause because it contains a subject ('the DNA') and a verb ('wraps') and can stand alone as a sentence. The second clause ('transcription factors can then access the genetic sequence and initiate the process of transcription') is also an independent clause with its own subject ('transcription factors') and verbs ('can access' and 'initiate').
Two independent clauses must be separated by a period, a semicolon, or a comma combined with a coordinating conjunction.
3
Evaluate the options to find the correct punctuation or conjunction that follows standard grammar rules.
The option with a semicolon ('proteins;') is the only grammatically correct way to join these two independent clauses. A comma alone ('proteins,') creates a comma splice; omitting punctuation entirely ('proteins') creates a run-on sentence; and using 'although' ('proteins, although') is logically incorrect because it incorrectly signals a contrast instead of a direct consequence.
Applying these rules identifies the grammatically correct option.

Key Concept

Linking Independent Clauses
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Topics

Clause Boundaries and Linking

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