Transcription                   . a. synthesizes new daughter DNA molecules from an existing DNA molecule; b. results in the synthesis of an RNA copy of a gene; c. pairs thymines (T) with adenines (A); d. occurs on ribosomes

Verified step by step guidance

1. Understand the process of transcription: Transcription is the process by which a segment of DNA is used as a template to synthesize a complementary RNA molecule. This is a key step in gene expression.
2. Eliminate incorrect options: Option (a) describes DNA replication, not transcription. Option (c) is incorrect because transcription involves pairing adenine (A) with uracil (U) in RNA, not thymine (T). Option (d) is incorrect because transcription occurs in the nucleus (in eukaryotes), not on ribosomes.
3. Focus on the correct option: Option (b) is correct because transcription results in the synthesis of an RNA copy of a gene, which is complementary to the DNA template strand.
4. Recall the base-pairing rules in transcription: During transcription, cytosine (C) pairs with guanine (G), and adenine (A) pairs with uracil (U) in RNA.
5. Conclude that transcription is the process described in option (b), as it accurately reflects the synthesis of an RNA molecule from a DNA template.

Key Concepts

Transcription

Transcription is the biological process in which the information encoded in a specific segment of DNA is copied into messenger RNA (mRNA). This process is essential for gene expression, allowing the genetic code to be translated into proteins. During transcription, RNA polymerase binds to the DNA and synthesizes a complementary RNA strand, which carries the genetic information from the nucleus to the cytoplasm.

RNA vs. DNA

RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) are both nucleic acids, but they have distinct structures and functions. RNA is typically single-stranded and contains uracil (U) instead of thymine (T), which is found in DNA. This difference is crucial during transcription, as RNA is synthesized based on the DNA template, resulting in an RNA copy that can be translated into proteins.

Role of Ribosomes

Ribosomes are cellular structures that play a critical role in translating mRNA into proteins, but they are not involved in the transcription process itself. Transcription occurs in the nucleus, where mRNA is synthesized, while ribosomes function in the cytoplasm, where they read the mRNA sequence and assemble amino acids into polypeptides. Understanding this distinction is vital for grasping the flow of genetic information in cells.