Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

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Study for the Biology STAAR Test. Improve your skills with flashcards and multiple choice questions, each question is accompanied by hints and explanations. Prepare for success!

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Which molecule serves as the template during DNA replication?

mRNA
Original DNA strand
tRNA
Amino acid sequence

The correct answer is: Original DNA strand

During DNA replication, the original DNA strand acts as the template for synthesizing a new complementary strand. This process involves the unwinding of the double helix structure of DNA, allowing each strand to serve as a guide for building its counterpart. The enzyme DNA polymerase recognizes the base pairs and adds complementary nucleotides—adenine pairs with thymine, and cytosine pairs with guanine—ensuring that the newly synthesized strands are accurate replicas of the original. In contrast, mRNA plays a role during transcription, not replication, by carrying genetic information from DNA to the ribosomes for protein synthesis. tRNA is involved in translating that information into proteins by bringing amino acids to the ribosomes, while the amino acid sequence is the end product of protein synthesis. Therefore, the original DNA strand is essential for ensuring that the genetic information is precisely copied during the replication process.